Do Dinh Sam-Nguyen Ngoc Binh

Assessment of Potential Productivity

of Forest Lands in Vietnam

Contents

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Index � Forcewods Forcewords

� Chapter I Scientific Bases for Mountains and Hillsides Potential Productivity Assessment

� Chapter II Potential productivity of forest land on mountain and hill sides � Chapter II

Table 1 Table 7 to Table 31

� Chapter II Table 2

Table 32 to table 55

� Chapter III Assessing the Potential Productivity of Coastal Sandy Soils for Use in Forestry.

� Chapter IV Assessing the productivity of mangrove saline and sulphate soils in the Mekong Delta

� Chapter V Assessment of site suitability for the cultivation of tree crops

� Chapter VI Development of shemes for site mapping and classification

� Abstract � Conclusion

Abstract

Conclusion and today forest land use problems in each region

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Do Dinh Sam-Nguyen Ngoc Binh

Assessment of Potential Productivity Of forest lands in vietnam

Statistical Publishing House Hanoi-2000

Foreword Soil is a natural resource and at the same time an environment of importance contributing to the growth and development of forests and their vegetation. Its study, in particular that of forest soils, has been developing to cover a wide range of subjects/areas; soil mapping and classification, physical and chemical properties of soil, soil biology, interactions of soil with other natural factors and human interventions... Besides, other areas of practical importance and related to applied soil science such as land use, land evaluation, land capability, assessment of land productivity, classification o lands or use in farming..., through receiving less attention of soil scientists and being studied with limited scope, began to get enough momentum in particular at the Forest Science Institute of Vietnam (FSIV). The period 1990-1995 has seen the success of the national research programme KN-03 dealing with “Forest Restoration and Forestry Development” under the management of FSIV and of another component research project on the “Assessment of Potential Productivity of Forest Land in Vietnam” and on forest site mapping. The assessment of forest land potential productivity has been made nation-wide in eight economic regions on four types of land found on: mountain-and hillsides, coastal sandy areas, mangrove wetlands and sulphated soils. The work has come to good success with the collaboration of a number of agencies/authorities from the Soil and Agro-Chemicals Institute, the Vietnam National University based at Hanoi, the Vietnamese Soil Scientist Assiociation and FSIV itself all of them being whole-heartedly involved in our project of land evaluation. Our sincere thanks go to all of them, in particular to Dr. Ngo Dinh Que (FSIV), Prof. Dr. Le Van Khoa (Vietnam National University), Dr. Pham Tien Hoang (Soil and Agro-Chemicals Institute). The final report of the Project has been edited by Prof. Dr. Do Dinh Sam and Eng. Nguyen Ngoc Binh, all working for FSIV. As it is, the report may still have some mistakes, for which the authors would like to be apologized and which can be made good again through the assistance of the readership.

The Authors

Introduction The Forestry Sector is entrusted with the task of protecting and managing over nine million hectares of forested areas and 11 hectares of non-forested areas (Agriculture, Forestry and Fisheries Statistics, 1994), of which eight million hectares are definitely allocated of forestry management and development (Forestry Inventory and Planning Institute (FIPI), 1994; Central Cadastral Office, 1995). Under the present setting, efforts are to be made to protect and build up the local forest resource base, in particular through the implementation of the national five-million hectare plantation programme so to reach in the year 2010 a forest vegetation cover of 43% as it was prevailing before 1943. To help the programme achieve its objectives, overall assessments of forest soils and their productivity should be made not only to point out the availability of land for the purpose, but also to better know the capability of the land on which the programme is going to be carried out. The work looks enormous, and the key challenge is to find out a set of methodologies most appropriate for the diverse forest soil conditions of this country. The methodologies selected should meet the following two basic requirements. They sould enable:

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- Surveyors to give overall assessments on forest land productivity i.e. the capability of the land, its physical favourable conditions and limitations when under use;

- Foresters to carry out systematic collection of information nation-wide for prompt data processing and

analyses. As a first step, it is essential to have a brief review/scanning of the main methodologies related to soil mapping and classification, land capability assessment, so far applied in this country and elsewhere the world over. 1/ Soil Survey, Mapping and Classification for Soil Mape Production The related methodologies are widely used by soil scientists. In Vietnam surveys have been carried out for soil classification and production of soil maps scaled at 1/1000,000 for the whole country, at 1/500,000 for the North, and at 1/100,000 for the provinces. And recent studies have also been made to shift from the present soil classification of Vietnam based on soil genesis to the soil mapping systems as advocated by FAO-UNESCO. Research results on soil classification, properties of soils, and soil maps now available can be used as scientific bases for the assessment of potential productivity of forest lands, but above all, the present study has its own track to go. 2/ Classification of Forest Soils Based on Forest Vegetation Types Natural forests in Vietnam are classified into evergreen broad-leaved forests and deciduous or semi-deciduous coniferous mixed broad-leaved and bamboo ones, and saline wetlands, mangroves..., and their soils can be named after the vegetation types they support. Soils under other vegetation types such as shrubs, high grasses... can also be categorized accordingly as above. The method is usually applied in forests inventories, for assessment of natural resources; it can bring in some ideas of land capability and productivity, but the information given is sometimes of broader implication, not adequate enough for effective land farming. 3/ Land Capability and Suitability Approaches This is a process in which land productivity and suitability for one/several land use types are described and assessed to allow the most intensive agriculture use of the land without risk of soil erosion. To apply this approach in our study two concepts, that of land capability and that of land suitability should be well defined. Moreover, there is not one land capability classification but many; the method has been developed first in the U-S, but as it tends to spread to other countries, there are lots of modifications and variations. On the other hand, the assessment of land suitability into different levels of high suitability, fair suitability, low suitability, very low suitability... for a land use type or a crop should be made after careful consideration of the properties of the soil groups/types and the requirements of the farming systems or the crops themselves. The task is not at all easy although in Vietnam, a training course on the matter was held by FAO, and trial applications were also organized in agriculture and forestry (Hoang Xuan Ty, 1992; Tran An Phong, Bui Quang Toan, 1992). 4/ The US Department of Agriculture System The system has been developed by the US Department of Agriculture; it tries to show out the limitations or hazards caused by factors that are not easy to change such as land splopes, soil depths, climatic conditions, and other permanent characteristics of soils, so to divide lands into classes, subclasses and units. In this system, land in the US is allocated into 8 classes of which soils in class I have no, or only slight, permanent limitations, and soils in class VIII have lots of limitations and are rough even for woodland or grazing. Particular problems in erosion (e), in excess water (w), in soil (s) the depth of which may limit the development of plant/tree root systems ... are also studies and used to divide classes into subclasses; for example II-e, III-e... are subclasses in which erosion hazards have created problems. The method can be used with success for the division of land use units in a country as a whole or in regions / areas within each country for a wide range of land uses (rice cultivation, food crops, cash crops, cattle grazing, forest protection or plantation...) The endeavour to assess land potential productivity in particular that of forest lands is something now in Vietnam, therefore efforts made to select and develop appropriate methodologies for the task in hand seems to be quite hard. And what is given below is the results of national research project KN03-01 for “Assessment of Potential Productivity of Forest Lands, period 1992-1995”, which is a component of a bigger national programme KN03 dealing with “ Forest Restoration and Forestry Development”. Activities for the implementation of the KN03-01 research project have been developed separately: * In eight economic regions: the North West , the North East, the North Central Region, the North Central Vietnam,

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the Coastal South Central Vietnam, the Eastern South Vietnam, the High Plateaux of Tay Nguyen and the Mekong Delta, with the Red Delta being excluded because of its arable land mainly meant for agriculture; and * For four different types of land on:

· Mountain-and hillsides;

· Coastal sandy soils;

· The Mekong Delta saline wetlands; and

· The Mekong Delta acid sulphate soils. Because there is no method of assessment suitable for all types of land under study.

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Chapter 1

Scientific Bases for Mountains and Hillsides Potential Productivity Assessment

Three-fourths of the total land mess of Vietnam are mountains and hillsides, of which 77 per cent are

classified as forest lands including both forested and non-forested areas. The Forest Inventory and planning Institute (FIPI, 1995) has identified as many as 19.01 million hectares of forest lands, of which on-forested and forested areas cover 9.8 million and 9.3 million hectares respectively, with enclaves of forest lands in the Red River and the Mekong Deltas amounting to some 265,00 hectares only.

The mountains and hillsides under discussion are grouped into forest lands on: - Mountains including high mountains, medium mountains and mountains; - High plateau; - Semi peneplains or peneplains; - Old alluvia terraces; and - Karstic formations.

However, the classification of topographic types, especially those of mountains, hills and/or peneplains have not received general acceptance of all scientists. Some of them argue that hills and mountains naturally occur on elevations of below and above 500m above horizon respectively (Vu Tu Lap, Sukin...). Others referring to local climatic conditions, distribution of vegetation cover and forest soils, maintain that under the Vietnamese conditions, elevations of below and above 300m above horizon can be taken as the limits separating hills and mountains (Fridland, Duong Ke Can, W. Schwanecker, Tran Ngu Phuong, Nguyen Van Khanh...), which seems to be more realistic under local conditions.

Another term-that of upland has recently appeared in a number of rural development projects, in particular those dealing with forestry activities, but no clear definition has ever been given. It can be understood as the mountain area is consisted with the Midland where hillsides prevail-for the development of which priorities and bigger efforts in terms of technical assistance and infrastructure building are needed because of its poorer accessibility and socio-economic conditions. The whole area of mountain - end hillsides being classified as forest lands under study has been divided into seven regions, on which forest inventories and resource cruising have been made for ages. They are: the North West, the North Center Region, the North East, the North Central Vietnam region (better known as the Former

4th zone), the Coastal South Central Vietnam region, the High Platcaux, and Eastern South Vietnam. For appropriate forest land potential productivity assessment on mountain-and hillsides, careful studies of

main soil groups and identification of bases and criteria for that purpose seem to be essential. 1.1. Main Features of Soil Groups Found on Forest Lands. 1.1.1. Distribution of main soil groups and types.

Soil classification in Vietnam has been made based upon the soil genesis processes prevailing in the country. Recently a group of soil scientists of the Vietnamese Soil Scientists Association have carries out research to shift from that soil classification to the present soil classification and mapping system of FAO-UNESCO. However, most national soil science workers are still using the older soil classification and mapping system being applied since 1978 in particular for studies of soils developed on mountain-and hillsides.

The development of forest soils on mountain-and hillsides has mainly been effected by their location on mountains at different elevations that may reach over 3,000m above sea Laval in this country and the existence of other specific topographic types such as old alluvia terraces, peneplains and high plateaus. · Soil genesis and the weathering of rocks and parent materials at various elevations have created conditions for the

formation of the following soil groups: - Typical feralit soils (Ferralsols) found at low elevations, below 700m and 700-800m above sea level in the

North and the South respectively; - Mountain feralit soils (Humic Ferralsols) occurring at elevations above 700m (or 800m) above sea level and

up to 2,000m asl. The soil can be referred to as a subtropical soil type and is named yellow Alisol by some scientists (Nguyen Ngoc Binh);

- Alit soils on high mountain (Alisol proper) found at elevations above 2,000m asl. · Old alluvia terraces under different soil formation conditions have also developed number of soil types, they are:

- Yellowish brown soils on old alluvia found on undulating hillsides mainly in the Midland and Mountain

Area of the North Vietnam, the Coastal South Central Vietnam, the Former 4th zone, and in parts of the Eastern South Vietnam ; the soil is characterized by its texture ranging from loam to clay loam ;

- Grey soils on old alluvia mainly noticed at the Eastern South Vietnam, on the High Plateau, with feature varying from sandy loam to loamy send. The soils are found in flat areas, sometimes in poorly drained and waterlogged areas in particular in the rainy season; most of them are rated as being degraded. · On the peneplains in particular the peneplains of Easup (on the High Plateau at Tay Nguyen), there are lost areas of

poor drainage, being waterlogged in the rainy season but very dry in the otherwise dry season, thus creating conditions for the formation of grey soils of poor nutrient content, developed on granite, sandstone, siltskne and old alluvia... ; they are the sites of deciduous open forests of Dipterocarps in which Dipterocarpus obtusifolius and

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D.tuberculatus are dominant species. · Other high platcaux of Vietnam are: the High Plateau of Moc Chau, and the High Plateau of Tay Nguyen ; most of

them are endowed with fertile red soils developed on limestone’s and with reddish brown, or yellowish brown soils developed on basaltic parent materials.

· There are also orange of atonal soils found at high elevations ; they been various features that differ from the hillsides in the mountainsides, but are mainly severely eroded, showing either apparent stones on rocks (Leptosols) and as a rule are meant for forestry.

· In the mountain and hilly areas, there are also two other soil groups, namely known as black soils (Luvisols), the main characteristic of which come from their parent materials, and the brown soils of semi-arid zones (Lixisols) developed under specific climatic conditions.

1.1.2. Basic features of the main soil groups found on mountain-and hillsides. 1.1.2.1. Mountain reddish yellow humic soil group. 1.1.2.2. The group has been developed mainly from ergillaceous and metamorphic rocks (39 percent of the total group

area), acid magma (27.5% percent of same) sandstone (18.5 percent of same) alkaline/neutral magma (2.8 percent of same) and from limestone (2 percent).

Though being of different parent materials, they all have some common features as described below:

The soils are of yellow colour mainly, because of high moisture conditions prevailing on the mountains, and their relatively high contents of mobile Fe and accumulated Al. When the parent materials are richer in Fe, the developing soils can be yellowish red in colour, with the yellow colour going to prevail with higher and higher elevations. · They are soils of medium weathering crust. · Their humus content is relatively high amounting to 8-10% and above, with also high C/N ratio ; therefore their

contents of N,P,K at surface layers are rated as relatively important. · The soils are however of acid reaction, with high mobile Al content and low base saturation percentage. · The changes in terms of soil productivity between sites under forest cover and those being non-forested (i.e. under

shrubs, and high grasses) are not so apparent as on feralit soils: the organic content of soil surface layers on shrubs and nnchs can remain quite high (5-6%), and soil moisture content acceptable because of color climatic, high humidity, moderate precipitation, and low evaporation.

However, the reddish yellow humic soils developed on acid magma and the yellowish ones on sandstones are

of lower productivity, soil depth and lighter feature. 1.1.2.2. Yellowish red brown soil group.

Their main characteristics are well described by soil scientists: · The soils are of low cession exchange capacity as they are mainly developed from kaolinite, and very low mineral

content. Besides kaolinite there are some other minerals rich in Al and Fe hydroxides that can fix phosphorus in these soils and cause silica leach.

· The soil organic matter ratio remains low, except for soils developed on basaltic and calcareous parent materials ; and the process of decomposition is quite high resulting in a low C/N ratio of 8-11%.

· The soil reaction is cleanly acid, with low base saturation percentage, apparent leaching of basic earth metals, and low percentage of available P (even in soils of high percentage of total P as those of brown colour developed on basalts.

The degradation process seems K be immediate after deforestation, with soil depth and organic matter

content all becoming less and less and the formation of concretions and leterites cleaner and cleaner following careless human interventions.

Developing on a range of parent materials, the yellowing red soil group has a variable productivity potential, the main points of which are: · The sub-group of soils developed on basaltic parent materials. They are sub-divided into three types: The reddish

brown soil, the yellowish brown soil, and the violet brown soil. Most of them are of high productivity potential: - with soils under forests being of: 6-8% of organic matter content (even at 100cm from surface layers, the organic matter content still remaining quite high with not less than 1-1,5%) ; - 0.20-0.30% of total N ; - high total P2O5 but low available P2O5 (because of the presence of a high percentage of Fe and Al) ; and - low K2O content.

The soils are rich in clays but under forest they are of good structure, drainage and endowed with high wilting points. When the forest cover is cleared, the soils can get very dry and compact and both their drainage and structure severely impeded or even destroyed.

Reddish brown soils are known for their soil depths, while other yellowish soils of the group are found to be thinner and to occur in areas of high precipitation and humidity.

The violet brown soils on the other hand can be noticed on the foot of easy hillsides, where they are of a fertile alluvial type.

A matter of much importance is related to what happens following unwanted human interventions (for instance deforestation or abusive land use...), the impacts of which have caused extensive areas of basaltic soils to become marginal, in particular on the High Plateaux of Tay Nguyen.

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That degradation of basaltic soils can be noticed through changes in soil mineral nutrients, physical properties, indicator plants and soil profile characteristics (Nguyen Dinh Ky, 1986). In general the soils become more compact, much drier, with their surface layers almost reaching plant wilting points or somewhat lower in terms of soil moisture. (Nguyen Huy Son, 1998). Research by the senior author (Do Dinh Sam, 1983) also shows that degraded basaltic soils have had their humus contents reduced to their lower limits of 3-4%, and their nitrification processes almost arrested. · The sub-group of reddish brown soils developed on limestones.

They are known as reddish brown soils and red soils. The reddish brown soils on limestones can be seen on mountain sides supporting some forests in which Parapentace tonkinensis (vernacular Nghien) either alone or mixed with Garcinia fagracoides (vernacular Trai) dominates. The red soils on the other hand are found on the foots of rocky mountains on at their lower slopes where forests have been destroyed.

Brown soils prove to be more productive than the red ones. Generally speaking both brown and red soils on

limestones are endowed with high organic matter and contents, high amounts of Ca++ and Mg++, granular soil structure, water-resistant soil aggregates, good soil porosity and water percolation. The soils are of heavy texture, with clayey particules contributing to high wilting points but unwanted soil compactness during the dry season. · The sub-group of violet brown soil on violet schists.

The sub-group with its unique violet soil type can be found on easy and low hillsides of Son La, Thanh Hoa and Nghe An. Its parent materials are violet argillaceou rocks, thus providing a specific colour to soils developed on them. Soil depths vary from low to medium, but unlike. The forest soils, violet soils are basic or central in their

reaction (their pH by water being 7-7.5), and their remounts of eachan-geable Ca++ and Mg++ are high (reaching 25-27 milliequi-valents/100g of soil), resulting in a high base saturation percentage of 92-97%. The soil is also rich in humus content (6-7%) and in total N (0.3-0.35).

The soil is well known for its high productivity, and soil scientist argue that it has its origin from alluvia, which, have been raised up following tectonic changes of the earth’s crust. · The sub-group of yellowish red soils developed on argillaceous and metamorphic rocks.

They are soils of medium productivity, being developed on micaschists and metamorphic greiss, that can be found in the North Central Region and in the provinces of Quang Nam and Quang Ngai (in Coastal South Central Vietnam). The Weathering crust of soil is very deep as encountered in Phu Tho and Yen Bai provinces. They are the sites of former luxuriant forests and most today plantations of cash crops in particular tea... The soil texture varies from clay to loam. · The sub-group of yellowish soils on sandstones.

There are soils of low productivity because of their fine sand texture, low humus and N contents, poor soil structure. However due their K content and their wilting points these soils can support some farming crops such as maize, tuber crops, ground nut beans, bananas... with reasonable success. Plantations of other crops such as pines and cashews can be also noticed on these soils. 1.1.2.3. Grey soil group

They are a group of low productivity soils, often referred to as degraded grey soils. Grey soils can be found on old alluvia in slightly undulating or flat areas, where waterlogging can cause them to become true gley.

Grey soils can be also seen developing on sandstones, granites in some sloping land areas. Their main features are: high soil acidity, poor humus and N contents, poor amounts of bases and basic earth

metals. Their soil texture is light, and very often high amounts of concretions can be found on gray soils developed on old alluvia. Therefore, intensive farming methods should be used on these soils for the growing of cashews and dipterocarps (such as Dipterocarpus alatus and Hopea odorate) for them to bring in good returns. 1.1.2.4. Black soil group.

The group is well known with the following soil types: · Black soils on calcareous rocks.

They are found on the tops and upper slopes of limestone mountains. Their soil profiles are not fully developed and only show two distinguish-able horizons of A and C. The soils are endowed with a neutral pH, and high

contents of humus and N. The amounts of bases, especially Ca++ abound, resulting in a very high base saturation

percentage of 98%. Available P2O5 and K2O are poor and adequate respectively in these soils ; and their structure is found to be water-resistant. The main forest tree species that thrive there are Dacrydium pierrei (vernucular Hoang Dan) and Podocarpus fleuryi (vernucular Kim Giao). · Black soils on spongy volcanic rocks.

They can be noticed on the High Plateau of Tay Nguyen, where typical open forests of Dipterocarps prevail in the landscape and in some other areas in the provinces of Dong Nai and Song Be.

The soils are of thin layers, and spongy volcanic rocks can be seen on their surface. Their surface layers have the specific black colour coming from the high amount of accumulated humus (searching up to 6-8% but sometimes lower-only 3-4% - due to the presence of much Mg in soils) ; and a concretion layer can be noticed next to the humus one . The soils are rich in nutrients, of good physical conditions, granular structure quite resistant to dispersion by water.

Plantations of Teak (Tectona grandis) thrive well on black soils ; and in many other areas, mixed stands of Fabaceae and Dipterocarceae can be found on these soils.

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· Black soils on colluviel products from red basaltic soils.

These soils can be seen in flat area, where colluviel products from red basaltic soils are accumulated due to surface run-off. They are not typical black soils, and their organic matter contents are not so high as found in reddish brown basaltic soils. · Carbonated black soils.

These soils are developed in areas where water tables come near to the soil surface, and where hard water

rich in Ca++ vows can be found. The soils are rich in humus, total N, and are endowed with granular structure resistant

to water. They are also porous and in their B-horizon, bean-like CaCo3, Fe and Al concretions often abound. 1.1.2.5. Semi-arid brown soil group.

The group can be found in areas/regions of low atmospheric precipitation of less than 1,000mm, often of only 600-700mm per annum, in Vietnam. They occur in Ninh Thuan, Binh Thuan, Nha Ho (Thuan Hai) and in Muong Xen (Nghe An), on the upstream watershed of the Song Me river.

The main vegetation types found there are spiny shrubs, drought-resistant grasses growing on sandy soils, or other-wise deciduous Dipterocarps shedding their leaves in the dry season, some species of Lagcrotroemia and or Lac insect host-tree species, other forest tree crops used in plantations on these soils are cesuarines, Lac insect host-tree species and drought-resistant tree crops.

Due to semi-arid climatic conditions, the process of ferralit formation is weak, the soil reaction is almost neutral, and the total amounts of exchangeable bases are quite high, resulting in a base saturation percentage of about 60-80%. Generally speaking, the soils are poor in humus and N contents, with a C/N ratio of only 4-7%, but their

amount of K2O at their surface layers are found K be almost adequate. 1.1.2.6. The group of stony and bouldary eroded soils.

The group comprises all types of soils of thin and very thin layers ; they are bredly eroded to the extent that, in some area/regions, outcrops can be noticed. Under these conditions, our main tecks on these soils are to protect the existing cover vegetation ; and in some areas in the Deltas and in the Midlands, labour-intensive plantations with Pinus merkusii (vernucular Thong nhua), Eucalyptus exerta (vernucular Bach dan lieu) or acacias for soil protection and improvement are the only feasible activities/projects.

Besides the above-mentioned soil groups and types, in the mountains one can find another group of montane yellow “alit” (at elevations above 2,000m) with two main soil types: that of high mountain peat soil, and that of high mountain humic alit soil.

In short, soil groups and types as identified by Do Dinh Sam and Nguyen Ngoc Binh based on soil genesis following elevations, parent materials and human interventions can be summarized as follows.

1.High mountain alit soil group (elevations above 2,000m asl) with: - Alisol proper - High mountain peat soil - High mountain humic alit soil. 2. Mountain reddish yellow humic soil group (700-2,000m asl) with:

-Reddish yellow humic soil on ergillaceous and metamorphic rocks. -Reddish yellow humic soil on acid magma -Reddish yellow humic soil on alkaline/mental magma

-Reddish yellow humic soil on sandstone -Reddish yellow humic soil on limestone. 3.Yellowish red/brown soil group (= typical feralit soils) (at elevations below 700-800m asl)

-Developed on basaltic parent materials, with: +Reddish brown soil on basaltic parent materials +Yellowish brown soil on basaltic parent materials +Violet brown soil on basaltic parent materials -Developed on limestone, with: +Reddish brown soil on limestone +Red soil on limestone -Developed on violet schist, with: +Violet brown soil on violet schist. -Developed on ergilaceous and matomophic rocks, with: +Yellowish red soil on ergillaceous and matomophic rock. -Developed on sandstones, with: +Yellowish soil on sandstone. -Developed on old alluvia with: +Yellowish brown soil on old alluvia. 4.Grey soil group, with: +Grey soil on old alluvia. +Grey soil on sandstone, granite. 5.Black soil group, with: +Black soil on calcareous rocks. +Black soil on spongy volcanic rocks. +Black soil on colluvial red basaltic products. +Carbonated black soil.

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6.Semi-arid soil group with: +Semi-arid brown soil. 7.Stone and bonldery eroded soil group. 1.1.3. Basic factors for potential productivity assessment.

The main feature of soil groups/types prevailing on forest lands as described above can help us identify their specific characterics and/or their degradation or restoration processes showing their productivity and select other factors criteria for assessment: They are: 1.1.3.1. Land slopes.

Sloping lands are the main characteristics found in any forest landscapes and their impacts on soil productivity, farming practices and land uses are considerable.

Following a study made by Nguyen Tu Siem (1999) on the mountain-and hillsides, lands with slopes above

250 can account for 63% of the total, and those with lower slopes of below 150 amount to only 24.9%. 1.1.3.2. Soil erosion and nutrient leaching.

Sloping lands and high slopes are important factors causing soil erosion and soil nutrient leaching to occur in particular in areas of high and concentrated precipitation.

The process of soil erosion with its diverse forms has been studied by Ton Gia Huyen, Bui Quang Toan in the North West (1964,1965), by Nguyen Quang My on the High Plateau of Tay Nguyen (1983,1985), and on a number of hillsides in Northern Vietnam by Thai Phien and Nguyen Tu Siem (1965,1986,1995,1998) and by Chu Dinh Hoang (1962,1963). Typical soil erosion on forest soils are mainly stydied by Nguyen Xuan Quat, Bui Nganh (1964) in the forested area of Cau Hai (Phu Tho), by Bui Nganh, Vu Van Me, Nguyen Danh Mo (1986) in Huu Lung (Lang Son), and by Nguyen Ngoc Lung, Vo Dai Hai (1994) on the High Plateau of Tay Nguyen.

These studies show that soil erosion, and soil nutrient leaching are the results of a range of factors: high precipation, types of soils and their susceptibility, the lie of the lands, their, slopes and not the least the farming systems and land uses being practiced. Below are some recent research results on erosion and its impacts under three types of conditions: · Agricultural farming systems on sloping lands with low and moderate slopes; · Swiddening on mountain-sides with higher slopes; and · Forest land farming in a number of vegetation types. a/ Soil erosion in typical agricultural farming systems. Research has been made in two farming systems used for the cultivation of dry farm crops and cash crops (in particular coffee, tea...) during the period 1990-1997 by the Soils and Agro Chemicals Institute in a number of land use research projects in cooperation with international agencies. The main results obtained can be summarized as follows: · Soil erosion is always a limiting factor for farm crops grown on mountain-and hillsides (of low slopes), seriously

affecting their production/yields. Variations in terms of run-off and soil losses are considerable following different practices and conditions. Consecutive recordings for 5-6 years show that soils of different mechanical composition

on low slopes of 5-80 and on moderate slopes of 15-170 and in open areas (corned with grasses or conventional farm crops) without conservation practice can carry a mean annual run-off of 2100-2300 m/ha, the total amount of which may vary from 700 to 4000 m depending local annual precipitation - with peak surface run-off sometimes reaching 8000 m - and account for 46-70% of total annual rainfall, resulting in an average soil loss of 7-23 tons/ha, with peaks reaching 50-170 tons/ha. Lower soil loss of 7 tons/ha/ennum is recorded in open basaltic areas with low

slopes (ranging from 5 to 80). On upland rice swidden field farming across contour lines, soil loss on basaltic soils is much higher reaching up to 70 tons/ha/ennum, sometimes even to 130 tons/ha (Bui Quang My, 1980). Therefore, on open sites without conservation practice, soil loss due to erosion by water may be of the order of 70-170 tons/ha/ennum. And in case of sloping lands being ploughed, soil losses might be much higher.

· The use of conservation practices through vegetation cover either by mixcropping or creating green belts... has proved to be effective in countering soil erosion, reducing soil losses by 30-80% without completely eliminating the scouring impacts (Nguyen Tu Siem, Thai Phien, 1998).

· Soil nutrients losses in particular in terms of organic matter, N, P2O5 and K2O are much higher than the same taken up by agricultural crops.

b/ Soil erosion on swidden fields. Research on soil erosion on swidden fields as farmed by ethnic minorities is not many. Nevertheless, some research has been made by Bui Quang Toan (1962) on the matter. It shows well that some 1.5-3cm of surface soil are eroded annually, resulting in a soil loss of 130-200 tons per ha and per year.

Table 1. Soil erosion in swidden agriculture in the North West

Crop Surface soil being eroded (in cm) Soil loss (ton/ha)

First crop (1962) Second crop (1963) Third crop (1964)

0.79 0.88 0.77

119.2 134.0 115.5

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Other research activities made in Dac Lac on swidden agriculture practiced on reddish brown basaltic soils across contour lines show that soil losses under these conditions amount to 72.2 tons/ha/ennum. When the farming is made following contour lines and with the protection of green belts of legumes, soil losses will be much reduced, to only 48% or 35 ton/ha/annum (Thai Phien et al , 1998) Bui Quang My (1980) with his research activities at Pleiku on

basaltic soils also points to the fact that the cultivation of upland rice on slopes of 8-150 can cause considerable soil losses of about 130 tons per hectare and per year. However, observations at Huu Lung (Lang Son) on swidden fields

planted with cassava on sloping lands of 250 on ergillaceous rocks show an average annual surface run-off of 797 cu.m. per hectare, resulting in a soil loss estimated at 1.62 tons/ha/annum only. (Nguyen Danh Mo, 1986). c/ Erosion on forest land Forest lands as understand here are those covered with forest trees and/with shrubs/high grasses following abusive exploitation of natural resources, on which only sparse trees can be noticed if any. A point of much relevance to land farming is the fact that unlike farmland, forest lands either forested or not are not subjected to severe soil erosion and scouring by water. Research made by Bui Nganh, Vu Van Me, Nguyen Danh

Mo (1972-1974) shows that soil erosion on forest soils developed from ergillaceous rocks on slopes of 12-150 at Huu Lung (Lang Son) under mixed secondary regrowths of 0.7-0.8 canopy density is not at all intense, with a run-off of

84cu.m/ha/annum only and soil losses amounting to a minimum of 0.23 tons/ha/annum ; on higher slopes of 250, the corresponding values are 142 cu.m/ha/annum and 0.28 tons/ha/annum respectively. This shows well the countering effects of forest trees and vegetation in particular in reductry surface run-off and soil losses ; for instance higher land slopes can increase the surface run-off by 1.7 times but the resulting soil losses do not go up in the same way, it has only increased from 0.23 ton to 0.28 ton/ha/annum. Forest lands after clearing and being removed of all shrubs for cattle grozing can have a surface run-off flow of 2,229cu.m/ha/annum (or 2.5 times higher than before and reaching the some order of intensity is on farmlands) but soil losses-though being tripled - are of the order of 3.1 tons/ha/annum only. Research on soil erosion and surface run-off in

the High Plateau of Tay Nguyen on bazaltic reddish brown soils (on slopes of 5-80) covered with a range of vegetation types also shows similar remlts (Nguyen Ngoc Lung, Vo Dai Hai, 1993-1994). Under mixed and multi-storied natural forests, with a canopy density of 0.7-0.8, the surface run-off flow is of the under of 220 cu.m./ha/annum and the resulting soil losses amount to only 1.28 tons/ha/annum, and under savamahs of thick. Imperat cylindra cover - which can afford good soil protection - the soil losses are only 1.07 times higher, being 1.37 tons/ha/annum, whereas the surface run-off flow has increased by 1.7 times, reaching 380 cu.m. per hectare. It can based that under natural forests, and other secondary regrowths of shrubs and high grasses, the changes in soil erosion and surface run-off remain minimal, and soil losses when compared with the same on farmlands amount to only 1/25 or 1/100 times of those experience there. The reduction of surface run-off in natural multi-storied forests has also created conditions for the formation of a ground water flow which plap a very important role in farm crops cultivation and the storage of water resource in the areas next to forests. On deforested areas where plantations have been re-created, conditions are favourable to controlling soil erosion, but research results on that matter remain inadequate. Observations during less than a year from July to November at

Hoa Binh on soils developed on ergillaceous rocks and on slopes of 150 in a range of plantations established with Acacia auriculiformis (vernacular Keo la tram), Acacia mangium (vernacular Keo tai tuong) and bamboos show that soil losses are not very high, amounting to only 0.15-0.2 tons/ha, but the surface run-off remains almost the same, with almost no differences between before and after plantation (823 cu.m./ha and 765 cu.m. respectively) ; the ground water flow does not seem to get improved. Soil losses, on the other hand, can not be higher because an already high rate of soil erosion was prevailing there when the sites were denuded.

Table 2 -Surface run-off and soil losses in different forest vegetation types

Total (for three crops) 2.44 368.7

Location

Parent rocks

Slopes

Vegetation type

Surface run-off

(m3/ha)

Soil losses (ton/ha)

Huu Lung (Lang Son)

Argilla- ceous 15-20

0 Mixed natural forests, canopy density 0.7-0.8

84.3 0.23

rocks Forest lands after timber extruc-tion to convert them into grazing lands

2.229.0 3.08

Thick shrubs 403.8 0.64 Mangliatia glauca plantation,

16 years of age 242.6 0.36

Pygeum arborcum plantation, 7 years of age

166.8 0.39

KonHaNung (Gia Lai)

Basaltic rocks 8-10

0 Mixed natural forest, canopy density 0.7-0.8

220.5 1.28

Degraded forests with ground cover vegetation removed

310.3 3.4

Bamboo forest, canopy density 0.7

383.8 1.35

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The processes of soil erosion and nutrient leaching have caused forest soils to get degraded, leading to stony and bouldery eroded soils, the to the formation of “problem soils”. 1.1.3.3. Accumulation of organic matter and N is an important factor on sloping forest lands. One of the most important processes contributing to forest soil degradation is the leaching of organic matter, humus and N from soils when forests are removed. The annual amount of litter fall of branches, twigs and leaves in natural forests amounts to 11-12.5 tons/ha, and the same from Manglietia glauca, mixed Styrax tonkinensis, rend pure bamboo plantations is 9.8 tons, 10 tons and 9.5 tons per year respectively (Hoang Xuan Ty). In Pinus kesiya stands at Lam Dong, the same is estimated 8-12.5 tons/ha/annum (Do Dinh Sam, Ngo Que). All of them are the sources for organic matter and nutrient accumulation in forest soils. That accumulation process of humus and N under forests varies with climatic, edaphic and vegetal conditions (See Table 3)

Table 3 - Amounts of humus and N accumulated in soil layer (0-100cm) under forests (in tons/ha)

* Source: Do Dinh Sam, 1990 Summing up, one can say that: At elevations 500-1800m esl, the amount of accumulated humus in the upper 100cm soil layer under hardwoods varies from 180 tons/ha to 848 tons/ha and that of accumulated N varies from 11-26 tons/ha ; whereas under conifers within the elevation range of 500-1500m esl, the accumulated amount of humus ranges from 157 tons to 256 tons, and that of N from 7 to 9.5 tons/ha. At elevations below 100m esl, the amount of accumulated N seems to be higher than that of humus because of lower C/N ratios. Under same climatic and vegetational conditions at high elevations, the accumulation process of organic matter may vary with difference in parent materials and in particular the mechanical composition of soils.

Table 4 - Humus and N contents in soil surface layers (in %) (Average values)

* Source: Do Dinh Sam, 1990 Generally speaking, the accumulation process of organic matter in soils developed on alkaline and neutral magmas, on limesknes is higher than the same on ergillaceous and metamorphic parent materials, and the lowest amount of organic matter is found in soils developed on sandstone. When the forests are destroyed, forest soils under grasses and shrubs begin to have their humus and N contents removed at an accelerated rate in particular at lower elevations of below 1000m esl. With the plantation of eucalypts, pines, acacias, teak, and dipterocarps on open and denuded hillsides, the process of humus accumulation in particular at soil surface layers begins to get improved (see table 5). Table 5 - Humus contents in soil surface layers in plantations

Imperata cylindrica savannah (very thick)

380.0 1.37

Binh Thanh (Hoa Binh;

Argilla-ceous 25

0 Acacia auriculiformis plantation 765.4 0.152

6 month rocks Acacia mangium plantation 795.0 0.202 observations Bamboo plantation 823.1 0.178

Elevations >1700m 1000-1700m 500-1000m <500m Forest types Hardwood Hardwood Conifer Hardwood Conifer Hardwood Accumulated humus

848 385 256 254 157 180-240

Accumulated N 26.4 10.8 9.5 14 7.2 11-12 C/N ratio 18.8-20.6 10.8-11.6 15.1-18.6 12-13.5 12.5-14.5 8-11

Elevations 1000-1700m 500-1000m <500m Vegetation cover

Hard-wood

Conifer Shrub &

grasses

Hard-wood

Conifer Shrub &

grasses

Hard-wood

Shrub &

grasses Humus content

8.5 9.5 8.5 5.9 4.6 2.9-4.2 3-5.7 1.4-2.4

N content 0.407 0.258 0.248 0.281 0.198 0.143-0.167

0.162-0.292

0.086-0.126

Species Humus contents in soil surface layers (%) Eucalyptus camalotulensis/tereticornis 1.5 Pinus merkusii 1.94 Pinus massoniana 2.76

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* Source: Do Dinh Sam, 1995 Nitrogen in forest soils is mainly available under the form of ammonium N because of soil acidity. It should be mentioned have that the process of ammonification can be much reduced to become even arrested under the conditions of open and denuded hillsides, although the contents of total N in soils are quite high ; this is the case with reddish brown feralit soils on basalts, which can experience shortage of available N. Under natural forests on basaltic reddish

brown soil, the ammonification process can releau up to 20.7 mg of NH4+ per/100g of soil, but when the forests are

abusively exploited, that process will be severely impeded, releasing only 12-13mg of NH4+ per 100 g of soil, and

when the forests are completely destroyed the process will come to a stand still, with almost no ammonium in being released even under optimal temperature and moisture conditions (Do Dinh Sam, 1986,1990). 1.1.3.4. Soil acidity, P deficiency and low absorption capacity. Other factors effecting soil fertility and crop yields in agriculture are also of relevance to forest land farming. They are high soil acidity under forests producing lot of raw humus, fixation of P because of high percentages of Fe

and Al in soils, low absorption capacity of soil in which H+ and Al+++ always prevail. 1.1.3.5. Physical properties of soils and soil water. Forest lands are mainly located on moderate to steep slopes of over 250. But when they are covered with vegetation, their soils are endowed with good physical conditions and high water-holding capacity. Their high soil

porosity provides a relatively low volume weight (= apparent specific gravity) of about 0.7-0.9 g/cm3 ; but when the

forest vegetation is removed, the soil volume weight may increase to 1.2-1.4 g/cm3. Under forest, the soils are also endowed with good aggregate structure, with a low karinski dispersion ratio of 10-15% (Do Dinh Sam, 1986) ; and the soils there are always moist/wet and never reach their wilting points. Observations made at Cau Hai (Phu Tho) during 1962-1965 in natural forests yielded the results described above ; and recently other research activities by Nguyen Ngoc Lung, Vo Dai Hai (1995) also point to high soil moisture prevailing under natural forests of the High Plateaux of Tay Nguyen (Table 6). However, when the forest cover is removed, there will be big changes in the physical properties of soils and movements of soil water, showing a real bring to soil degradation. The soil becomes compact, much drier and harder, with soil moisture going down to the wilting point and below this in particular in the dry season. Research made by Nguyen Huy Son (1998) on degraded basaltic soils of Tay Nguyen on a number of sites (including denuded hillsides and forests at different stages of restoration/development) shows that there can be a quite large zone in soils where their moisture is at wilting point (moisture below 25% of field capacity) found at a depth of 20cm from the soil surface and extending over six months of the dry season, and a smaller zone in soils where their

moisture is at its hygroscopic coefficients (moisture Hymax below 17% of field capacity) extending over four months of the dry season and found at a depth of about 10cm from the soil surface, when the forest vegetation is removed or on its way to restoration. Table 6 - Soil moisture in a number of vegetation types (during March, April, May and June, 1993 and 1994)

1.1.3.6. Soil depth. This is an important factor for soil productivity assessment in particular on sloping lands. It is a well-known fact that in Vietnam most soils are deep even in the mountains.

Pinus ceribaea 1.33 Pinus kesiya 5.19 Acacia mangium 2.12 Acacia auriculiformis 2.23 Tectona grandis 3.76 Hopea odorata 3.55

Vegetation type

Soil moisture at different depths (cm) (in percent of field capacity)

0-5 20-25 40-45 60-65 1. Open and denuded hillsides 6.8 14.2 25.6 27.3 2.Grassy savannahs + shrubs 23.5 27.9 30.8 31.2 3. Restored forest after swiddening 24.7 29.1 30.2 32.5 4.Three-storied natural forest, canopy cover 0.3-0.4

29.6 32.7 34.8 33.6

4.Three-storied natural forest, canopy cover 0.7-0.8

33.8 35.9 36.0 34.3

4.Two-storied natural forest, canopy cover 0.3-0.4

32.0 33.6 34.1 34.2

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However, there are two processes that can reduce the beneficial effects of soil depths when the vegetation cover is cleared ; they are soil erosion and the process of concretion formation and laterization, all of which occur quite intensively so to require careful investigations. As mentioned earlier besides the beneficial effects of forest trees other vegetation types, not excluding those of shrubs and high grasses, can play a very important role in controlling the scouring compacts of surface run-off to counter soil erosion and therefore to keep forest soil depths acceptable for land uses in more than are region. 1.2. Methodologies used for potential productivity assessment of forest lands. 1.2.1. Identification of criteria and standards for potential productivity assessment of forest lands on mountain - and

hillsides. The selection and identification of these should meet two main requirements: · They should have a very close relationship with soil productivity so to facilitate assessment for land use; · They should facilitate the collection of related information for diagnosis and assessment nation-wide and for easy

data processing. Based on the main factors affecting potential soil productivity as mentioned earlier, the authors have selected four factors for assessment. They are: land slope, soil depth, surface soil organic matter content and soil texture. 1.2.1.1. Land slope The factor proves to have a very close relationship with soil productivity, first with soil erosion and nutrients leaching following different farming practices and systems leading to severe limitations on land uses. Land slopes are divided into four classes for assessment: -Class 1: slopes < 150 ; -Class 2: slopes of 15-250 ; -Class 3: slopes of 25-350 ; and -Class 4: slopes of <350. The measurement of slopes can be made on topographic maps. 1.2.1.2. Soil depth. Being one of most important factors effecting soil productivity, soil depths are to be assessed based on a number of soil maps available. Soil depths are divided into three classes: -Class 1 and class 2: above (>) 100cm ; -Class 3 : 50-100cm ; and -Class 4 : less than (<) 50cm. 1.2.1.3. Surface soil organic matter content. The factor is known to have a strong impact on forest land productivity. However its values vary with elevations above sea level, and soil and vegetation types. Therefore, the division of surface soil organic matter content into classes can not be done in the same way based on the values found for all soil types. With the data in hand, the division of organic matter content into classes should be approached differently for four soil groups/types having different contents under different climatic, edophic and vegetational conditions. These for soil groups are: high mountain humic elit soils, mountain reddish yellow humic soils, yellowish red soils on alkaline and neutral magmas/limestones and other feralit soils, with the first three soil groups contain relatively higher amounts of organic mattes than other feralit soils. On the other hand, realties do not show a steady relationship between soil organic matter contents and forest vegetation growth and development. For instance, on mountain reddish yellow humic soils where forests are cleared out, leaving behind only shrubs and high grasses, the surface soil organic matter contents still come to 3-4% or above, with contents below 3% prevailing on soils going to get degraded. On reddish brown soil developed on basalts on the southern high plateaux, surface soil organic matter content of 3% is also reported to occur on degraded basaltic soils, whereas on other feralit soils prevailing at lower elevations, percentages of 3-5% of organic matter at surface layers are usually found in only non-disturbed natural forests and regrowths thriving very well. Taking into consideration all there facts, the whole range of surface soil organic matter contents is divided into four classes as follow: -Class 1: Very rich in humus (Mainly found in primary forests experiencing almost no destruction, and on the following forest soil types): +High mountain humic alit soil +Mountain reddish yellow humic soil, with surface soil organic matter content of ³ 10% + Feralit soil on alkaline and neutral magmas ³ 8% + Other soil types ³ 5% -Class 2: Rich in humus + Mountain reddish yellow humic soil 5-10% + Feralit soil on alkaline and neutral magmas 5-8% + Other soil types 3-5% -Class 3: Medium in humus + Mountain reddish yellow humic soil 3-5% + Feralit soil on alkaline and neutral magmas 3-5% + Other soil types 2-3% -Class 4: Poor in humus + Mountain reddish yellow soil <3% + Feralit soil on alkaline and neutral magmas <3%

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+ Other soil types <2% The division in classes is made through summing up soil analysis results in terms of organic matter content in different soil types developed in different vegetation types and in different economic regions. Soil maps showing different soil group/types, their textural classes and their location (in natural forests, savannahs, shrubs or plantations at different cluationss) are used to estimate surface soil organic matter contents as first approaches. 1.2.1.4. Soil texture. For this factor of much importance to land use, assessment is made based on soil maps. The lake available show only three textural classes: loamy sand, loam and clay. In our assessment the same classes are used with: -Class 1 (and class 2): Loam -Class 3: Clay -Class 4: Loamy sand (with sand particles still dominating). 1.2.2. Consolidation for assessment. The four factors and their divisions into classes esmentioned above are studied one by one in each land use unit using a system of marks, with mark 1 for class 1, mark 2 for class 2 etc... for primary assessment in that unit. Then some consolidation is needed for on overall assessment of the potential productivity of the unit. For that a scale of four grades is proposed and their middle value can be taken to name the grade. The four grades for final assessment of forest land potential productivity are described as follows:

Grade 1: The unit has few limitations for land use, its potential productivity is high. Grade 2: The unit has some limitations for land use, its potential productivity is fair. Grade 3: The unit shows out a number of serious limitations for land use; its potential productivity is medium. Mean mark: from 2.51 K 3.5.

Grade 4: The unit shows out a large number of limitation for land use ; its potential productivity is low. Mean mark: > 3.5. Although we have not hail special emphasis on any factors out of the four used for assessment, some due attention has been paid to soil depth and soil texture because of their high importance in land use. In the can of these two being both rated as of class 4, the final assessment will be lowered by one grade. For example, a land use unit is rated of classes 1,2,4 and 4 in terms of land slope, surface soil organic matter content, soil depth and soil texture respectively, its potential productivity could have been rated as of grade 3, because the mean of component marks given (1+2+4+4):4 = 2.75 ; but with the occurrence of class 4 in the two factors (soil depth and soil texture), it is rated as of grade 4. 1.2.3. Steps to follow in forest land potential productivity assessment. 1.2.3.1. Map reading. - Primary assessments in seven economic regions as mentioned earlier are made on maps scaled at 1/250,000, with each square on maps of 2cm x 2cm representing 25 square kilometers. - Topographic maps and other thematic maps dealing with soil types, groups, vegetation types can provide enough information on the following six factors: elevations above sea level, land slopes, soil types, soil texture, soil depth, and vegetation type or present land use. - Then division into classes of the four factors of importance for assessment based on the information obtained follows. 1.2.3.2. Field surveys. Field surveys are made identify land use patterns ; natural forests, plantations, and or agroforestry systems ..., to know the performance and yields of different farming systems and then to collect soil samples for analyses. 1.2.3.3. Soil analyses. Soil analyses are carried out to obtain information on : organic matter contents, total N, soil reactions,

exchangeable bases, available P2O5 and K2O, and mechanical composition of soils. 1.2.3.4. Data processing on computer. Processings are made on computers: -To adjust different results obtained with much emphasis leid upon those obtained from field surveys/checks. -Data logging - into produce four maps on computer showing land slopes (divided in four classes), soil depths (three classes) soil texture (three classes), organic matter content (four class) and a map showing overall forest land potential productivity for each region based on the component factors as mentioned, to be followed by transfers of data on regional base maps scoled at 1/250,000. 1.2.4. Identification of land use units. Steps should be also carried out to define sets of soil/land characteristics and physical conditions related to land use so to identify such units. A land use unit is an area quite homogenous in terms of its key site features. The five following factors are chosen for that purpose:

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-Altitude above sea level ; -Main soil groups/types ; -Land slopes ; -Soil depth ; and -Atmospheric precipitation. Each factor on the other hand is to be subdivided into a number classes for use in different regions. And the number of land use units will be increased when the subdivision into classes becomes more sophisticated for more detailed surveys. Finally, the results of our tentative assessment of forest land potential productivity will be given in two main sets of documents related to: Division in and number of land use units in each of the seven regions under study; and Assessment of forest land potential productivity in each of the regions following four grades: grade 1, grade 2, grade 3, and grade 4 showing increasingly higher permanent limitations or hazards when used for forestry. Back to contents Next>>

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Chapter 2

Potential productivity of forest land on mountain and hill sides

2.1/ The North-West The North West comprises three provinces: Lai Chau, Son La and Hoa Binh 2.1.1/ Assessment of forest land productivity based upon four main factors a/ Land slope: Based on existing maps and using an appropriate application on computer, we arrive at the following conclusions: The North -West is endowed with 66% of its land being of over 35o of slope, details of which can be summed up as follows; in the two provinces of Lai Chau and Son La, abruptly sloping land accounts for 61-76%; in Hoa Binh the

same amounts to 50% and lands under 15o of slope to about 21%, while they are of only 0.7-0.8% in the two provinces of Son La and Lai Chau. As the forest cover is also very low (only 9-10% of total land area) in the North West, the problem of soil conservation there becomes a challenge when economic development in the region is to be tackled.

Any case it is quite irrational to affect all lands of over 30o of slope there to a protection status. Rational management of all vegetation types (bamboo groves, shrubs and even high grasses of Imperata cylindrica should be combined with that of forests to combat erosion. Forest lands with their slopes and the distribution of different slope classes are shown in Tables 7 and 8. From the tables, one can find that non-forested areas are mainly found on high slopes, at class 4 (58%) and at class 3 (17%); in particular in Son La and Lai Chau, 55-65% of their non-forested areas are found on slope of class 4. In Son La, non-forested areas on slope class 3 cover 26%. A specific situation is found in Hoa Binh where non-forested area

accounts for almost 16% on lands of slope class 1 (slope below 15o), whereas almost all lands under slope class 3 (with

slopes ranging from 25-35o) are covered with forests, and the areas under forests and of denuded hill and mountain-sides are almost the same (28% and 32% respectively), on lands of slope class 4. b/ Soil depth (Tables 9 and 10) The findings given in Tables 9 and 10 point to the fact that although high slopes and severely destroyed forests are prevailing in the North West, soil depths there can yield good conditions for plant growth, with soils of a depth over 100 cm for 29% of the total and those of a depth of 50-100 cm for 45%, they all total up to 75% or three-fourths of forest land there. The situation in Hoa Binh especially looks encouraging, with 17-21% of its forested areas being on soils of soil depth classes 1 (over 100 cm) and 2 (50-100 cm), and its 60% of non-forested area on the same soil classes; only 20% of its non-forested areas are on the soil depth class of below 50 cm. These conditions provide favourable conditions to land development for both forestry and agriculture. c/ Soil texture (Tables 11 and 12) Soils of the North West are mainly sandy and loamy in nature with loam accounting for almost the same percentage in the three provinces (reaching 41% of the region total), and sandy soils or loamy sand extending nearly over 43% of the region total (except for the case of Lai Chau where sandy soils amount to over 50%), Clayey soils do not abound, and in particular at Lai Chau they account for only 5% of the provincial total. In the region, non-forested areas are found with the same percentage (37% on loams and sandy soils (or loamy sand). The soil texture looks quite suitable for tree crop cultivation, in spite of the fact that soil productivity there is not high, and that soil conservation should be deal with carefully so to avoid adverse soil erosion in the region. d/ Soil organic matter content (Tables 13 and 14) Under the present conditions of climate, vegetation and human intervention prevailing in the North West, soils with very rich humus content account for only 6% of the total area, those with a rich amount of humus (class 2) account for 36% and those with a medium and poor amounts of humus class 3 and class 4 for 26% and 28% receptively. A quite high percentage of 60% of the total region forest land area, the soil of which being rich and medium in humus contents shows that in spite of everything, the site quality of the region is not severely affected. Only in Hoa Binh when compared with the two other provinces of Son La and Lai Chau are the soils of poor and medium humus content prevailing with a percentage of 35 and 38%, showing to the fact that at lower elevations the humus accumulation tends to slow down, due mainly to human interventions. Soils very rich in humus content do not prevail on non-forested areas of region, extending only from 1 to 3% of each relevant provincial forest land. However, in Son La and Lai Chau, soils rich in humus content of class 2 are seen extending over non-forested areas reaching percentages of 37 and 40%; and soils of medium and poor humus contents on non-forested areas account for 45% of forest land in the average. In general, forest soils of the North West can be rated as of rich and medium in humus content.

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e/ General assessment of land productivity and conditions for land use in the North West

Tables 15 and 16 point to the fact that: 63% of the forest land in the North West can be rated as of grade 3, meaning that they have a medium productivity and that they can show out some limitations in land use because of their high slopes and partly their low soil depth (< 50 cm) and high soil texture (sandy soils) The area under grade 3 in Hoa Binh is relatively (i.e in percentage) smaller by a half than the same found in each of the two provinces of Lai Chau and Son La. However, with regard to the percentage of forest land of grade 2, Hoa Binh is found to have a percentage somewhat higher by 2 times than the same of the two other provinces under study, because of its lower land slopes and better soil texture. The same tendency is kept going on non-forested areas, with forest land of grade 3 prevailing in Son La and Lai Chau while forest land of grade 2 having a higher percentage in Hoa Binh. On forested areas lands of grade 1 and 2 are highest at Hoa Binh (amounting to 13%) when compared with land of same grade found in the two other provinces of Son La and Lai Chau. In short for forestry land use, the soils in the North West can still provide some favourable conditions as their organic matter content and their depths are rated as quite acceptable in spite of forests being destroyed and high land slopes occurring there. 2.1.2/ Land use units in the North West The main factors selected for the identification of land use units are: a/ Altitude above sea level: divided into 4 classes: < 500 m (1); 500-1000 m (2); 1000-2000 m (3) and

Ø 2000 m (4) b/ Main soil groups or types: 10 soil types (not including those meant for agricultural farming alluvial soils, and soils on valley bottoms.... ) (1) Reddish brown soil on basic magmas and limestones: Fk +Fv (2) Yellowish red soil on argillaceous and metamorphic rocks: Fs (3) Reddish yellow soil on acid magma and sandstones: Fa +Fq (4) Yellowish brown soil on old alluvia: Fp (5) Violet brown soil on violet sandstones and schists: Ft (6) Humic soil on alkaline magmas and limestone: Hk+Hv (7) Humic soil on argillaceous and metamorphic rocks: Hs (8) Humic soil on sandstone and acid magma: Hq+Ha (9) Peat soil : A (10) Black soil (on serpentine +calcareous rocks): Rk +Rv

c/ Land slope divided into 4 classes:

* < 15o (1); * 15-25o (2); * 25-35o (3); and * > 35o (4) d/ Soil depths: divided into 3 classes: * > 100 cm (1); * 50-100 cm (2) ; and * < 50 cm (3)

e/ Rainfall: divided into 4 classes:

* > 2,400 mm (1) * 2,000-2,4000 mm (2); * 1,600-2,000 mm (3); and * < 1,600 mm (4) The main findings are: - At elevations below (<) 500 m above sea level: 49 land use units, with soils of 50-100 cm deep prevailing (90%),

slopes over class 2, and rainfall mainly of classes 3-4; the largest land use unit here covers 30,000 hectares.

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- At elevations of 500-1,000 m above sea level: 119 land use units, with most slopes being of classes 3-4 (>25o), soil depths prevailing at classes 1-2 (>50 cm), rainfall mainly of classes 2-3 (more rain water than at 500 m a.s.l). The largest land use unit covers more than 127,500 hectares.

- At elevations of 1,000-2,000 m (above sea level): 69 land use units, with most slopes being of classes 3-4

(>25o) , soil depths prevailing at classes 1 -2 (> 50 cm), rainfall mainly of classes 3-4 (less rain than at 500-1,000 m (a.s.l). The largest land use unit extends over 167,500 hectares.

- At elevations higher than 2,000 m (above sea level): only 2 land use units of no relevance to most farmers/landusers .

The main points again are: Soils with high slopes, found mainly on elevations over 500 m above sea level with annual rainfall ranging from 1,600 mm to 2,400 mm, wild vegetation somewhat degraded, but still having moderate humus content and moderate productivity, because of their parent materials of clacareous rocks, alkaline magmas, argillaceous and metarphormic rocks, old alluvia and violet sandstones and schists. 2.1.3/ Forest land use based on productivity assessment As mentioned earlier, more than 60% of the forest land in the North West can be rated as of grade 3; and the most favourable conditions prevailing there are soil depths and surface soil organic matter content. The main limitations

come from high land slopes with slopes classes of 25-35o and above 35o being the most important stumbling-blocks to overcome. * Therefore, effective forest land use in the North West should be made using the following principles: -Soil conservation always comes first, with emphasis being laid upon the basic task of consolidating the protective role of forests in all provinces, in particular at the watershed area of the Song Da, which is next to the hydroelectric power-generating water reservoir of Hoa Binh and which is extending over large tracts of land. Besides activities/projects to create new plantations, those related to strict protection of natural forests to accelerate regeneration also appear to be essential. -Methods and technologies for sloping land use/farming should be actively adapted/developed for sustainable forestry and agriculture development. The two favourable physical factors of soil depths and surface soil organic matter content should be harnessed to the utmost through the adoption of advanced agroforestry systems and improved selection of plant/tree species. -Agroforestry systems are the indispensable conditions (for enhancing the protective role of vegetation and conservative farming systems to provide good incomes to local farmers and to maintain the soil productivity) and at the same time seem to be the adequate ones because of favourable conditions of the land in terms of its productivity. -Agroforestry does not mean simply that agriculture and forest tree crops should be cultivated on the same piece of land, but that rational arrangements of crops should be planned for and made from the foot of hills to their slopes and higher up to their tops over larger and larger areas. -Swiddening by ethnic peoples and groups, in particular by the H'Mong, the Dzaos and the Thai should be improved first through assigning sites/zones for better land farming and soil erosion control. * In fact, some of the above principles have already been put into practice by ethnic communities in more than one locality of the region. -Protection forests at watershed areas have been established; a number of farming systems on sloping lands have been developed using hedgerows of nitrogen-fixing legumes to counten erosion; and rice terraces on slopes of mountains have been managed by some ethnic communities far ages. -The traditional swiddening practice is on its way to get improved with more and more agriculture and forest tree crops being grown in combination. Recently enough, some promoters, taking advantage of the local climatic and edaphic conditions began to grow cash and fruit crops, in particular tea, naulbarry and coffee (with coffee not thriving well because of frost). However, market outlets for some fruit products (apricots, plums...) cannot be easily found, when they are grown over extensive areas in the Region. -Other new agriculture and non-wood forest crops are also under trials by local ethnic groups. The H'Mong have cultivated Coix lacryma job (vernacular Y di) after one or two croppings of maize. In some high mountain areas the culture of Amomum tao kwa (vernacular Thao qua) has been tested under forest cover by the H'Mongs. -Local agroforestry systems have also been improved with upland rice mixecropped with squash/melon and or protected by rows of flax. And assignments of zones and sites for swiddening have been tested with good success in the North West in some provinces. -On the other hand plantations of tree crops (tung oil, bamboo, hybrid acacias, Eucalyptus urophylla ... in Hoa Binh, and lac-insect host trees at the watershed areas of the Song Ma) have yield good success. In more than one protection forest, the cultivation of indigenous tree species such as Chukrasia tabularis, Canarium spp. , Dracontomelum duperreanum... also thrives well. And promising results from natural forest protection to improve regeneration can be

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easily noticed in the Region. However, all the above is just a start, although a very good one, showing what should be done in forest land use in the North West. 2.2/ The North Central Region The North Central Region comprises six provinces: Lao Cai, Yen Bai, Tuyen Quang, Ha Giang, Phu Tho and Vinh Phu (with the last two ones being parts of the former province of Vinh Phu). 2.2.1/ Assessment of forest land productivity in the North Central region based upon four main factors:

a/ Land slopes (Table 17)

In the North Central Region, the lie of land in terms of slopes can be assessed as follows: -Forest land under slope classes III (25-30o) and IV (above 35o, accounts for 79% of the total. -Forested and non-forested areas under slope class III there share the same percentage, but they are not evenly distributed in all provinces; for instance in Tuyen Quang these lands are almost covered with vegetation, while in Yen Bai, Lao Cai and Vinh Phu provinces non-forested areas cover larger areas. -In all provinces, except Tuyen Quang, most forest lands under slope class IV are non-forested, but they are mainly found on limestone mountains or denuded mountain-sides

b/ Soil depth (Table 18)

Soils with depths of about 100 cm and 50-100 cm prevail in the region, extending over 80% of the total, of which non-forested areas appear to extend over large areas, except in Tuyen Quang, thus offering favourable conditions for forestry farming/development. Land with soil depth of less than 50 cm is found only in Vinh Phu, of which 20% are still denuded.

c/ Soil texture (Table 19)

Most forest soils in the North Central Region offer good conditions for forestry development as they are loams of good tilth (97%). Clayey soils account for only 2.9% and sandy soils are almost non-existent.

d/ Organic matter content (Table 20)

Soil very rich and rich in humus content account for a high percentage of the total, reaching 54%, those with medium humus content for 39%, thus making most forest lands in the North Central region (above 90%) favourable for tree growth, in particular with regard to soil organic matter content. Non-forested areas are mainly noticed on lands with medium in humus content, which however is not less than 3%. e/ General assessment of forest land productivity in the North Central Region (Table 21)

· Most forest lands in the North Central Region can be noted as of grade 2, having fair productivity. Non-forested areas on land of this grade account for the same percentage of 40% as a whole, with some provinces such as Vinh Phu, Lao Cai, Yen Bai having a higher percentage of 50-60 % of land of this grade being non-forested.

· Some 24% of forest land rated as of grade 3 in Ha Giang remain non-forested.

2.2.2/ Land use units in the North Central Region The main factors selected for the identification of land use units are: a/ Altitutde above sea level: divided into 6 classes: < 100 m (1); 100-300 m (2); 300-500 m (3); 500-1,000 m (4); 1,000-2,000 m (5); and > 2,000 m (6) b/ Main soil groups or types (sympol So): 10 soil types (1) Limestone;

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(2) Peat soil ; (3) Humic soil on high mountains; (4) Humic soil on limestones; (5) Humic soil on basic rocks; (6) Yellowish red soil on argillaceous and metamorphic rocks; (7) Yellowish brown soil on calcareous rocks; (8) Reddish brown soil on calcareous rocks; (9) Yellowish red soil on acid magma and sandstone; and (10) Yellowish brown soil on old alluvia. c/ Land slope divided into 4 classes * < 15o (1); * 15-25o (2); * 25-35o (3); and * > 35o (4) d/ Soil depth divided into 3 classes * > 100 cm (1); * 50-100 cm (2); and < 50 cm (3)

e/ Rainfall: divided into 4 classes:

· > 2,400 mm (1); · 2,000 -2,400 mm (2); · 1,600-2,000 mm (3); and · < 1,600 mm (4) The main findings are: - At elevations below 100 m there are 10 land use units, the main features of which are: · Slopes: below 15

o · Soil depths: mainly of class 2 (50-100 cm) and class 1 (above 100 cm) · Rainfall: high, varying from 2,000 to 2,400 mm At elevations between 100 and 300 m, there are 46 land use units, having the following features: · Area: the largest unit has an area about 60,000 ha; · Slopes: variable. From 15o to 35o; · Soil: yellowish red soils on acid magma, sandstone and metamorphic rocks; · Soil depths: variable covering the three classes used for the study; · Rainfall variable, but mainly in the range of 1,600-2,400 mm At elevations between 300 and 500 mm, there are 53 land use units; they are of following characteristics: · Area: the largest unit has an area of about 13,000 ha; · Slopes: variable, from 15o to 35o; · Soil: mainly typical feralit soils on acid magma, metamorphic rocks and sandstone. · Soil depths: mainly of classes 1 and 2 (above 100 cm and 50-100 cm); · Rainfall: mainly in the range of 1,600-2,000 mm, with some years with less than 1,600 mm. At elevations between 500 and 1,000 m, there are 70 land use units having soil depths of classes 1 and 2 and the large unit being of 125,000 ha. At elevations between 1,000 and 2,000 m, there are 62 land use units, the main features of which are: · Are: the largest unit has an area of about 160,000 ha; · Soil: mainly pests, humic soils on high mountains and Fs, Fa, Fq; · Soil depth: mainly of classes 1 and 2 (above 100 cm and 50-100 cm respectively); and · Rainfall: high. At elevations about 2,000 m, there are 11 land use units, having deep soils and endowed with high rainfall, the largest unit being of 52,500 ha. In short, the North Central Region offer, high potential for forestry development (except wherever the slopes being too high), because of its soil depths and higher rainfall.

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2.2.3/ Forest land use based on productivity assessment Forest land in the hilly and mountainous North Central Region can be regarded as of high productivity for forestry farming/ development. The main factors supporting this assessment are: deep soil, high humus content, and favourable soil texture. The only limiting factor to be considered is land slope, for which the following can be advanced: besides highly sloping rocky mountains extending over 14% of the total land area there, other slopes, although quite steep, are

within the range of 15-20o and 25-30o, which is normally in the range of forestry activities and operations in this country. So far, the principles for and the practice of forest land use in the North Central Region are shaped and put into being based on the following. *On forested areas, besides those forests meant for protection, of which stricter protection is always needed, other forests meant for production should be intently managed so to increase the yields of all stands involved. All existing natural forests even of poor or medium standing stock, should be managed following sound silvicultural practice through improved protection and maintenance, enrichment planting, stand improvement.. so to secure sustained production of timber at the next felling cycle. In fact, degraded forests of the region in which timber resources had been depleted, have been managed with success during these last 10 years. Examples of these can be seen in Phu Tho, Yen Bai, Tuyen Quang...; in particular the Forest Research Centre of Cau Hai (in Phu Tho), under the jurisdiction of FSIV has restored lots of degraded forests through well planned forest protection and maintenance, through thinning and improvement felling so to help target timber species regenerate and grow into young stands of high-value tree species. In otherwise severely degraded forests, FSIV has carried out research activities/projects to combine more and more intensively natural regeneration with enrichment planting. Belts of cleared vegetation are prepared to grow high seedlings of Talauma Gioi (vernacular Gioi). Cinnamomum spp (vernacular Re gung), Ormosa spp. (vernacular Rang rang); all of them perform very well parallel with other timber species regenerating naturally in non-distributed belt of vegetation left behind on the planting site, so to create mixed stands of valuable timber species. Conditions for forest restoration in the North Central Region appear to be wonderful under a wise management of the natural resources. *On non-forested areas, in particular in areas/zones where forest soils are not seriously demaged by water/wind erosion, the capability to restore the mixed natural forests can be much enhanced through the plantation of indigenous tree species following or parallel with the establishment of an artificial vegetation cover so that economic timber species can take advantage of the cover of shrubs to grow well. Trials and experiments based on these approaches have been carried out with success at the Forest Research Central of Cau Hai in Phu Tho. The North Central Region is also the site of a number of other studies, trials (provenance trials, plantation trials..) to select the right tree species for the right sites. Lots of forest tree crops such as Styrax tonkinensis, Acacia mangium, bamboo species, eucalyptus... have been tested in the region with success. Eucalyptus urophylla at 8 years of age can yield as many as 13.7 cu.m/ha/annum on good sites, on sites of medium quality the production can reach 9.0 cu.m per hectare and per year. Styrax tonkinensis also performs very well, years after plantation and on good site it yield up to 16.7 cu.m/ha/annum, and on medium quality site, its production is 10.9 cu.m/ha/annum on the average. Planters can even obtain higher production with Acacia mangium reaching at the same age of 8 years an average yield of 16.6 cu.m/ha/annum and a much higher result up to 20-25 cu.m/ha per year on better sites. On the other hand, the practice of integrated land farming (agroforestry, home gardens, forest gardens) and the establishment of mixed stands of indigenous tree species (Erythrophloelum fordii underplanted with pine apple; Manglietia glauca, Cinnamons, Styrax tonkinensis mix-cropped with upland rice, or cassava; tea mixed with tungoil), using a labour intensive approach also look very promising. Farming technologies on sloping lands to counter soil erosion, using hedgenous of nitrogen-fixing legumes such as Crotalaria spp. And Tephrosia candida..., have been tested with success and adopted by local farmers. In a nutshell, the productivity of the forest land in the North Central Region seems to be quite high as proved by a number of studies/research projects carried out in the region. Our main task to develop forestry in the region is to find out the right technology for the right site, to adapt the research results obtained to the realities of the land under farming to loam what experienced local farmers have done in specific areas, and then to plan for technical extension in the region so to improve the yields of both natural and man-made forests and the beneficial impacts of the protection forest systems therein. The only today challenge is to have better information on the markets of a number of goods and commodities such as pulpwood for paper making and cinnamon bark so to minimizing the fluctuations of the above markets for sustained development of forestry and its products in the region. 2.3/ The North East The North East comprises the following provinces: Cao Bang, Lang Son, Bac Thai (now being divided into Thai Nguyen and Bac Can) Quang Ninh and Ha Bac (now being divided into Bac Giang and Bac Ninh) 2.3.1/ Assessment of Forest Land Productivity (based on four main factors)

a/ Slopes (Tables 22 and 23)

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Based on data given in Tables 22 and 23, the following rating can be brought out: -In the North East, the areas meant for tree crop farming under a slope of less than 15o are very few, not exceeding 2%

of the total forest land. In some provinces such as Cao Bang and Lang Son, lands on gentle slopes (less than 15o) meant for forestry development are almost not existing. They are found highest only in Ha Bac (12%) and in Quang Ninh (5.5%) next highest. -Forest lands of slope class 4 and limestone mountains there account for 86% of the total. Forested lands account for 20-48% of the total under class 4; and non-forested areas and limestone extend over 30-37% of same, which can be seen in particular in Cao Bang. In short, forestry farming/development in the North East is going on mainly on forest land of slope class 4, with part of it being on land of slope class 3. b/ Soil depth Situations related to forest soil depths are described in Table 24 and 25. From there, the following can be said: -In the North East, forest lands with soil depths of classes I (above 100 cm) and II (50-100 cm) account for 26-28% of the total, and those with soil depth class IV (less than 50 cm) for 45% on the average. In Cao Bang and Lang Son, forest land with soil depth over 100 cm accounts for a higher percentage (28-42%), in particular at some areas of Cao Bang, they may account for up to 94.2% of local total. In the provinces of Ha Bac and Quang Ninh, forest land, with soils less than 50 cm deep dominates (77-79%). In the three provinces of Cao Bang, Bac Thai, Lang Son, forest land with soil depths over 50 cm accounts for 60-70% of the total. -Forested areas in Bac Thai extend over a high percentage of 22-24% of total forest land; and they are found on soils of depth classes II and III. -In the three provinces of Cao Bang, Bac Thai and Lang Son, non-forested area is found to have the same percentage on the three soil depth classes while Ha Bac and Quang Ninh have a higher percentage (33-42%) of land unit thin soil layers (less than 50 cm deep). In short, forest lands in the three provinces of Cao Bang, Bac Thai and Lang Son are known to be of better soil depth than the same found in Ha Bac and Quang Ninh. c/ Soil texture In term of soil texture, different features are described in Table 26 and 27 they allow us to bring forth the following -Soil texture in the North East is quite good. Loam is found to be extensive over 57% of total forest land, and at Cao Bang, Bac Thai, Lang Son the same is found even more extensively over 66-74% of total forest land area. Sandy soil ranks second and extends over 38% of the total, with the highest percentage (59-89%) being found in Ha Bac and Quang Ninh. -Forested areas in the three provinces of Cao Bang, Bac Thai and Lang Son are mainly found on loam but in Ha Bac and Quang Ninh the situation is not the same 45% of forested lands are loamy sand. -Non-forested areas in the four provinces of Cao Bang, Bac Thai, Lang Son and Ha Bac are of loamy soil, while in Quang Ninh non-forested areas are seen mainly on sandy soil. d/ Organic matter content Assessments on soil organic matter content are given in Tables 28 and 29, the main assessment on the matter are: -Forest soils in the North East vary from poor to moderately rich in humus (class 3 to class 4 of the scale established for assessment of humus content in percent); they account for 66.8% of the total forest land, with 73-84% in Cao Bang, Lang Son, Ha Bac and 54% (in Quang Ninh) and 35% (in Bac Thai). On the other side of the scale, i.e. forest soils rich in humus (class 2 can be found in Bac Thai (50%) and in Quang Ninh (30%). Forested areas with high humus content (class 2) can be found on quite extensive area in Bac Thai, Quang Ninh and Cao Bang (44-22%); and non-forested areas moderately rich and poor humus content can be seen mainly in Cao Bang (72%), Lang Son (68%) and Ha Bac (54%); in Bac Thai and Quang Ninh the same extends over smaller areas (33-38% only). In short, forest soils with rich humus content extend over larger areas in Bac Thai and Quang Ninh than in the remaining provinces of Cao Bang, Lang Son and Ha Bac. e/ General assessment of forest land potential in the North East -Based on the four factors criteria as used for assessment, one can say that:

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+ No land of grade 1 (high productivity; no limitations for use) can be found in the North East; + Land of grade 2 (fair productivity + some limitations for use: 15%; + Land of grade 3 (medium productivity with serious limitations for use): 67% + Land of grade 4 (poor productivity + high number of limitations): 16%. Quang Ninh has the high percentage (48%) of forest soils being finally assessed as of poor grade (grade 4); but most of these soils have been covered with vegetation (natural) or man-made forests). -Forested areas are mainly found on soils of grade 3 (18%), with Quang Ninh having a high percentage of forested area on soils of this grade (42%), while in other provinces the same percentage being only 12-17%. Non-forested areas are also mainly seen on soils of this grade (29%), with Lang Son and Bac Thai having higher percentages of 40-42%. The main limitations in forest land use in the North East are: high slopes lots of rocky mountains, thin soil layers (soil depths < 50 cm accounting for 45% on the average), poor soil organic matter content, light soil texture (loamy and sandy soil prevailing). 2.3.2/ Landuse units in the North East The main factors selected for identification are: a/ Altitude above sea level: divided into four (4) classes: < 300 m; 300-500 m; 500-1,000 m; and > 1,000 m b/ Main soil group or types (not including those mainly used for agriculture farming: alluvial soils, soils on valley bottoms, degraded arable soils): (1) Sandy soil; (2) Saline soil; (3) Yellowish red soil on old alluvium; (4) Yellowish red soil on sandstone and metamorphic rock; (5) Yellowish red soil on acid magma; (6) Reddish brown soil on limestone and alkaline magma; (7) Humic soil on mountain; (8) Eroded soil; and (9) Rocky mountain. c/ Slope gradient: divided into four (4) classes: · < 15o; · 15-25o; · 25-35o; and · > 35

o d/ Soil depths: three (3) classes: · > 100 cm; · 50-100 cm; and · < 50 cm. e/ Rainfall: four (4 ) classes: · > 2,000 mm; · 1,600-2,000 mm; · 1,200-1,600 mm; and · < 1,200 mm. A land unit is a complex in which these five (5) factors are so combined to create a whole; and in the North East, some 180 landuse units are thus identified. -At elevations below 300 m, there are 80 landuse units, which on the average extend over 25,000-50,000 hectares each (with some being smaller; 2,500-12,500 hectares only), and which show the following features: + Soils: yellowish red soils on sandstone and metamorphic rock; + Slopes: above 25o with some of them being of 15-25o; + Soil depth: thin layers below 50 cm; and + Rainfall: rated as adequate for forestry farming. At elevations between 300 and 500 m, there are 47 landuse units, (some of these units are quite large extending over 57,500-1,750,000 hectares) showing the following main features: + Soils: most of them are yellowish red soils on sandstone, metamorphic rock and acid magma; others are of reddish brown soils on limestone and alkaline magma having fair potential productivity;

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+ Slopes: above 25o

+ Soils depth: below 50 cm; and + Rainfall: low. -At elevations 500-1,000 m, there are 34 land use units having relatively smaller areas of 2,500-12,500 hectares, and showing the following main features; + Soils: Yellowish red soils, on sandstone, metamorphic rock and acid magmas, with patchy units of reddish brown soils on limestone; and + Rainfall: adequate for forestry farming. -At high elevations of 1,000 m above sea level, there are 18 land use units, of smaller areas (2,5000-5,000 hectares only) and having their soils developed either on sandstone, metamorphic rock, acid magma or on humus layers generating some humic soil on mountains; in particular some soils of moderate depth can be found at this elevation belt. 2.3.3/ Forest land use based on productivity assessment The above results point to the fact that the protection of existing forests and activities to increase the vegetation cover in the North East now become quite urgent because of the high slopes of the land, its poor productivity, and high percentage of loam and sandy soils. In the natural forests, the practice of selection felling should be carried out with care with a low and moderate rate of tree felling; in particular forest timber species occurring in limestones mountains should be dealt with great care, because of their high commercial value and the vulnerability of the sites. In all cases, the task of increasing the production of natural forests in the North East does not seem to be as easy as in the North Central Region; the main approach is to carry out a conservative management as practised for ages for the production of minetimber in the natural forests of Quang Ninh. Other practices of improved protection to restore the resources of forests and promote their regeneration made in combination with enrichment planting (for instance with the planting of Cannarium and Quercus as in Ha Bac) appear to be promising. The protection of saline wetlands, coastal mangroves of Quang Ninh also raises a lots of problems as they are of lower productivity than those found in the South of Vietnam. A number of commercial/industrial plantations of anise trees and Pinus merkusii at the same time require much more efforts for intensive management so to improve their production because they are/were established mainly on marginal sites in Lang Son and Quang Ninh. In spite of that low land/soil productivity, human efforts in terms of site and species selection have done something good in the region. By now, we can say that, in the case of the North East, careful surveys and studies can help planters grow well: anise trees, sandwood (Cunninghamia lanceolata), Pinus massoniana, P. merkusii and some species of eucalyptus for small timber and mine timber production in particular on sites which as a rule cannot support other indigenous timber species and/or cash crops, except for bamboos which can be grown with good success there. The practice of agroforestry, on the other hand, has proved to be very helpful in our task of better forest land management and soil conservation in the North East, parallel with the development of tree farms and /or agroforest farms. There are in the North East good examples of agroforestry in which Dendrocalamus membranaceus (vernacular Tre luong), Cinnamomum cassia (vernacular Que), are mix-cropped with upland rice and cassava, or Erythrophloelum fordii (vernacular Lim) is underplanted with pine apple. And the model of tree farms in which tree crops are grown at the same time with fruit crops such as litchi (vernacular Vai thieu) has brought in wealth to more than one household in the province of Ha Bac. 2.4/ The Coastal North Central Vietnam. (commonly known as the former 4th zone) The Coastal North Central Vietnam comprises the provinces of: Thanh Hoa, Nghe An, Ha Tinh, Quang Binh, Quang Tri and Thua Thien-Hue. 2.4.1/ Assessment of Forest Land Productivity in the Region The process is made based on the following factors: a/ Slopes (Table 32) -Forest lands in the Region are distributed as follows: + 45.5% of the total on slope class III (25-35o) + 28% of the total on slope class II (15-25o); and + 12-14% of the total on slope classes IV (above 35o) and I (below 15o) each. -Forested areas:

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+ Are found mainly on slopes of 25-35o: 30% of the total on the average, with Ha Tinh having the highest percentage (50%). + On slopes of 15-25o, relatively higher percentages (16-28%) of the total) are also found in the provinces of Ha Tinh, Thanh Hoa and Nghe An; and + On slopes above 35o, relatively higher percentage (20-31% of the total are found in the provinces of Thua Thien Hue, Quang Binh and Quang Tri. -Non-forested areas, on the other hand, are quite evenly distributed over the three slope classes of below 15o, 15-25o

and 25-35o; in particular non-forested areas in the provinces of Quang Binh, Quang Tri are found with a high

percentage of 17-23 % on slopes below 15o, while in Thanh Hoa and Nghe An they are found mainly only on slopes of

15-25o and 25-35o

b/ Soil depths (Table 33) -In the region, soil depth of 50-100 cm (class 3) can be found over 55% of the total forest land area, then next is soil depth of less then 50 cm (31%), other soil depth classes of 1 and 2 combined amount to only 14%. -Forested areas in the Coastal North Central Vietnam region, are mainly found on soil depth of class 3, accounting for a percentage of 33% on the average with Nghe An, Ha Tinh and Thanh Hoa having highest percentage of 37-50%. In Quang Binh and Thua Thien Hue provinces forested areas on soil depth class 4 account for a high percentage of 46%, while the average for forested area on slope of this class is only 16%. -Non -forested areas prevail on soil of depth class 3 being mainly found in Thanh Hoa and Nghe An (30-36% of the total) and Quang Tri (17% of same); while in Thua Thien Hue, non-forested areas on soil of class 4 prevail with 40% of the total.

c/ Soil texture (Table 34)

-Prevailing in the region are loams, accounting for 51% of the total forest land with Quang Binh, Quang Tri, Thua Thien Hue, Nghe An having the highest area of loamy soils (50-84%), then ranking next are clayey soils, covering an area of 37% on the average with large area of clayey soil being found at Ha Tinh and Thanh Hoa (64-68%). -Forested areas, however, are mainly found on clayey and loamy soils with 26.8% and 21% respectively, of which large forested areas (50%) on the two above-mentioned soils can be found in Thanh Hoa, Nghe An and Quang Binh provinces. However, most forested areas in Ha Tinh are found on soils of heavy texture (56%). Non-forested areas are found mainly on loams (30.3%), they are evenly distributed in all provinces therein, except Ha Tinh. d/ Organic matter content (Table 35) -With regard to soil organic matter, the following can be said: + Soil rich in humus and with medium humus content extend over large areas (68%) of forest land, in the region, and those poor in humus over 22% of same; + Depending on vegetation cover and parent materials available, soils with very high humus content can be found in Nghe An and Ha Tinh provinces on 14-24% of their forest lands; + Thanh Hoa is endowed with a large area (93% of its forest lands) of soils rich in humus and with medium humus content while + Soils poor in humus content are found in Quang Tri over 54% of its forest land. -42% of forested areas are found on soil rich/medium in humus, of which soils very rich in humus are found in Ha Tinh (about 68% of the total); forested areas on soils rich in humus also occur in other provinces of Quang Binh, Thanh Hoa, Nghe An, Thua Thien Hue over large areas. -20% of non-forested areas are found on soils medium in humus (of class 3) with larger areas of same can be found on soils of this quality in Thanh Hoa and Nghe An. And 49% and 27% of non-forested areas can be found on soils poorer in humus in the provinces of Quang Tri and Quang Binh respectively.

e/ General assessment of forest land productivity in the Coastal North Central Vietnam (Table 36)

-In general, forest land in the Coastal North Central Vietnam (or the former 4th zone) is rated as:

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+ Of grade 2 (fair productivity +minor limitation in landuse): over 39% of the total, of which larger areas (of 34-60% of the total) can be found in Ha Tinh, Nghe An and Thanh Hoa; + Of grade 3 (medium productivity +major limitations in use): 57%, of which larger areas (70-85% of the total) can be found in Thua Thien Hue, Quang Tri and Quang Binh. -Forested areas are found more on sites of grade 3 than on sites of grade 2. Those on sites of grade 2 are found mainly in Ha Tinh (55%), while those on sites of grade 3 evenly distributed in all provinces. -Non-forested areas can be found both on sites of grade 3 and 2 with almost the same percentage, with Nghe An having a larger percentage (of 32%) for sites of grade 2, and Quang Tri and Thua Thien Hue having the larger areas (48-49% of the total) for sites of grade 3. In short, forest soils in the Region are assessed to have difference in term of their productivity, with Thanh Hoa, Ha Tinh, Nghe An and parts of Quang Binh having soils in both forested and non-forested areas of best quality and more favourable farming conditions than those available in Quang Tri and Thua Thien Hue. The main limitations come from high land slopes and low soil depths. On the other hand, soils on non-forested areas are not rich in humus contents , most of them are of poor to medium in humus; soils rich in humus on these areas do not go over 4% of total provincial forest land area on the average. 2.4.2/ Land use Unit Identification It is based on: a/ Altitude (H) H1: < 300 m; H2: 300-500 m; H3: 500-1,000 m; and H4: > 1,000 m. b/ Main soil group or Types (So) = 10 types: So1: Sandy soils (C); So2: Eroded soil (E); So3: Yellowish red soil on argillaceous and metamorphic rocks (Fs); So4: Yellowish red soil on limestone (Fv); So5: Yellowish red soil on alkaline magma (Fk); So6: Yellowish red soil on sandstone and acid magma (Fq+Fa); So7: Red humic soil on limestone (Hv); So8: Humis soil on alkaline rocks (Hk); So9: Humic soil on acid magma and metamorphic rocks (Ha +Hs); and So10: Humic soil on sandstone (Hq). c & d-Slope and soil depth classes: as in all other regions e/ Rainfall: four classes: 2,400 mm; 2,000-2,400 mm; 1,600-2,000 mm; and < 1,600 mm. The findings in land use unit identification in the Region read as followed: · In Quang Tri province, there are 33 land use units of which: six (6) are found at elevations below 300 m; 11 units are found at elevations between 300 and 500 m; 11 units are found at elevations between 500 and 1,000 m; and 5 units are found at elevations above 1,000 m. Soil depths range from below 50 cm to 50-100 cm; and rainfall is less than 1,600 mm. The province does not offer favourable physical conditions for forestry development. · In Thua Thien Hue, there are 33 land use units, mainly found at elevations above 500 m, with slope classes

ranging from 15-25o and 25-35o, with soil depths less than 50 cm, and with rainfalls £ 1,600 mm. · In Thanh Hoa, there are 94 land use units, mainly found with slope classes varying from 15-25o to 25-35o, soil

depths of 50-100 cm and high rainfalls ranging from 2,000-2,400 mm. The province has favourable conditions for

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forestry development/farming. · In Nghe An, there are 96 land use units, found mainly at elevations of 500-1,000 m and above 1,000 m, with

slope classes from 15-25o to 25-35o, soil depths from 50-100 cm to above 100 cm, and rainfall varying from 1,600-2,000 mm to 2,000-2,400 mm.

· Ha Tinh is endowed with 37 land use units, found mainly at elevations less than 300 m and 300-500 m, with slope

classes ranging from 15-25o to 25-35o, soil depths of 50-100 cm, and quite high rainfall of 1,600-2,000 mm annually.

· Quang Binh, on the other hand, has been identified with 70 land use units, mainly found at elevations 300-500 m

and 500-1,000 m, with slope classes ranging from 15-25o to 25-35o, rarely reaching over 35o, with soil depths of 50-100 cm, and rainfall less than 1,600 mm and 1,600-2,00 mm.

In short, the first assessment related to land use units shows that the provinces of Thanh Hoa, Nghe An, Ha Tinh and Quang Binh are endowed with more favourable physical conditions for forest land use than others in the Region. 2.4.3/ Forest land use based on productivity assessment The assessment made paints to the fact that forested area in the Coastal North Vietnam is found on forest land of

grades 2 and 3, with slopes rated as of class 3 (25-35o). The standing volume of a number of forest stands is assessed to be quite high, and they have been under exploitation for years in Thanh Hoa, Nghe An and Quang Binh, but timber resource still remains adequate for continued logging with trees of Dbh above 50 cm still available, which shows well the productivity of the forest land in the Region. However, limitations come from high land slopes and soil depths ranging medium to low, which under the present setting requires much more careful forest protection not only in watershed areas for environmental conservation, but also in production forests where better management to improve restoration and regeneration, and as result of it, the productivity of the land should be regarded as a “must”. In fact, rational selection felling as practised in the forest enterprise of Huong Son (in Ha Tinh) for 30 years in a row has brought in sustained yields. However, signs have been noticed that in some parts there forest resource as a whole is going to decline, with more or less a swing to definitive degradation for want of adequate care. The problems ahead are stricter protection, better management, and intensive enrichment planting to be carried patiently and correctly. It seems best to critically study the success on the spot and elsewhere in the country in mastering the technique and art of cultivating indigenous timber species such as Michelia spp. (vernacular Gioi), Aglia gigantex (vernacular Goi), Tarriastia cochinchinensis (vernacular Huynh), Chukratia tabularis (vernacular Lat hoa). Pentophorum tonkinensis (vernacular Lim xet =Lim vang)...Well planned protection to promote restoration and regeneration is an important precondition and the main tool for that purpose not only in protection forests but also in a wide range of production forests. Field observations show well the high natural forest regeneration potential in the Region, even on sites which apparently can be regarded as being degraded as seen in Huong Son (Ha Tinh). Hundred of hectares have been regenerated, with Erythrophloelum fordii (vernacular Lim xanh) coming to recoglonize the sites on which the wrong use of Manglietia glauca (vernacular Mo) has been made good again. Non-forested areas are mainly endowed with land of grade 2 and 3; that of grade 4 extends over smaller areas and forest resource tree is thought to be capable of prompt restoration and regeneration when being taken care of. The main tree species used for plantation with success in the Region are: Pinus merkusii. eucalyptus, Acacia auriculiformis, A. mangium. Plantations of eucalyptus and Acacia auriculiformis (vernacular Keo la tram)...on an extensive and/or semi-intensive basis...are found to be capable of producing timber for paper making and chip production, in particular in the provinces of Quang Tri, Thua Thien Hue...and have provided some early incomes to planters. Plantations of Pinus merkusii, on the other hand, are productive and yield high yields of resin for industries. On sandy soils, as shown later, the plantation of casuarinas for moving sand stabilization can be managed so to accommodate a quite wide range of agricultural crops (rice, water melon, sweet potato, bean, onions...) as done by experienced local farmers. In inland sand dunes, the plantation of Acacia crassicarpa (vernacular Keo luoi liem) has recently been found successful so to replace Casuarinas and A. auriculiformis, which do not thrive well on this type of sandy soil. The management of coastal saline mangroves/wetlands has been started in some provinces, for instance, in Ha Tinh and Nghe An. However the pure plantation of pines, even tropical pines such as Pinus merkusii, has caused some pest outbreaks to occur, which though being controlled do not seem to have come to an end under the present conditions. On other hand, some other herbivores have begun to cause damage to eucalypt plantations (in particular those of E.camaldulensis and/or E.tereticornis) on a large scale mainly in the provinces of Quang Binh, Quang Tri and Thua Thien Hue. Therefore, some kind of integrated pest management should be developed to counter the ravages of the above-mentioned herbivores, in particular the establishment of mixed stands, the practice of crop rotation should be adopted so to contain the size of pest populations within reasonable limits. It should be mentioned here that the Region not long ago was famous for its rich forests and a wide range of prime timber species, the resources of which under the present setting are going to decline. Therefore, biodiversity and gene

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resources conservation should be one of the most important tasks of the Region. Better management of protected areas, nature resources and natural parks of Ben En, Bach Ma, Pu Mat...together with the protection and propagation of valuable tree crops such as Bassia pasquieri (vernacular Sen mu) in Thanh Hoa and Fokienia hodginsii (vernacular Pomu) in Nghe An and Quang Binh...should be never neglected. 2.5/ The Coastal South Central Vietnam The coastal South Central Vietnam comprises the former provinces of Quang Nam-Da Nang (now divided into Quang Nam and Da Nang), Nghia Binh (now divided into Quang Ngai and Binh Dinh), Phu Khanh (now divided into Phu Yen and Khanh Hoa) and Thuan Hai (now divided into Ninh Thuan and Binh Thuan). 2.5.1/ Assessment of forest land productivity

a/ Slope (Table 37)

-Forest land in the Region can be assessed as follows in terms of slope. + 50% of it being on slopes above 35o and 34% of same on slopes below 15o, pointing to the complex lie of the land in

the Region; out of the above, 58% can be found on slopes below 15o in the former province of Thuan Hai, and 73% and

60% can be found on slopes above 35o in Quang Nam, Da Nang and former Nghia Binh respectively. -Forested areas: + are found mainly on slopes of above 35o (34%) and on slopes below 15o: 11%. + 58% of those areas are found on slopes below 15o in Thuan Hai; and + In Quang Nam-Da Nang some 15% of same are found on slopes of above 35o. -Non-forested areas: + 23% and 16.6% of them are found on slopes below 15o and above 35o respectively; intermediary slopes, only less than 5% of non-forested areas can be noticed; + Equal area of non-forested areas sites can be noticed in all provinces on slopes less than 15o, but in Quang Na-Da

Nang and Nghia Binh non-forested areas on slopes above 35o seems to prevail in terms their acreage.

b/ Soil depths (Table 38)

In the Region, soil with depth of above 100 cm and less than 50 cm are found each with an equal acreage of 37-38% of the total forest land; and those with depth of 50-100 cm amount to 18%; out of which one can find that in Quang Nam-Da Nang and Thuan Hai up to 44.4% of forest land are found on soil depth class over 100 cm; on the other hand, 59% of forest lands in Nghia Binh and Phu Khanh are found on soils with depths not over 50 cm. -Forested areas: + Forested areas are evenly distributed in term of acreage on each of the three classes of soil depth (14-21%), with a relatively higher percentage likely to be seen on soils less than 50 cm deep; + Quang Nam-Da Nang and Thuan Hai have their forested areas evenly distributed on soils above 100 cm and 50-100 cm deep. + In Nghia Binh and Phu Khanh, forested areas are, on the contrary, found with a higher percentage (24-38%) on soils less than 50 cm deep. -Non-forested areas: + 23% and 15% of them are found on soils above 100 cm deep and on soils less than 50 cm deep respectively, of which. +Non-forested areas on soils above 100 cm deep have the same percentage in the terms of acreage/in all provinces; while + Nghia Binh and Phu Khanh have the highest percentage (21-35%) in the terms of acreage on soils less than 50 cm deep.

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c/ Soil texture (Table 39)

-Forest land with heavy soil texture accounts for a very high percentage of 84% of the total and is found to be evenly distributed in all provinces; sandy soils and loams each cover the same percentage of 8% in term of area, while in Thuan Hai sandy soil is extending over a bigger area (17%). -Forest areas are found mainly on clayey soils (50%). -Non-forested areas are also of clayey soils (35% of the total) in particular the prevail in the provinces of Quang Nam-Da Nang, Nghia Binh, Phu Khanh with higher percentages of 34-57% in term of acreage. This is not true for Thuan Hai where the same amounts to only 9%.

d/ Organic matter content (Table 40)

-An outstanding feature related to the properties of soils in the Coastal South Central Vietnam region is that its soils are not rich in humus, with soils rated poor in humus reaching a very high percentage of 73.5%, and those rated as medium in humus amounting to only 20% out of which Thuan Hai is well know for its high acreage (85% of soils poor in humus, and Quang Nam-Da Nang for its better soil conditions with forest soils medium in humus coming up to 30%, and forest soils poor in humus reaching 57%. -Forested areas are found on soils poor in humus are found on soils poor in humus with 29%, on soils medium with 18% ; only can soils rich in humus (class 2) be found in Quang Nam-Da Nang with a percentage of 11%. -Non-forested areas are found on soils poor in humus (44%), in particular this percentage can go up to 51-58% in Nghia Binh and Phu Khanh; soils of richer humus content in those non-forested areas account for only 0.4-1.6%.

e/ General assessment of forest land in the Coastal South Central Vietnam Region (Table 41)

The forest land in the Region do not up to grade 1; one can find there only forest sites of grade 2 and 3 with a percentage of 50%and land rated as of grade 4, which is of poor production and the use of which in spite of being feasible, can be met difficulties in terms of soil cultivation, is found with a high percentage of 42.6%. Non-forested areas account for a percentage 19.3% in this grade 4, and for a percentage of 21.3% in grade 2. The main limiting factors are high slopes (with those over 35o over 50% of the total) shallow soils (those of less than 50 cm deep over 38%) and poor humus content (soils of class 4 in term of humus content covering 73%). Besides, a low mean annual rainfall occurring in parts of the Region, can also have a strong local impact on land productivity. 2.5.1/ Land use unit identification The identification is made based on: a/ Altitude (H) H1: < 300 m; H2: 300-500 m; H3: 500-1,000 m; and H4: > 1,000 m. b/ Soil group or types (So): So1: Sandy soil; So2: Saline and acid sulphate soil; So3: Gley soil; So4: Semi-arid grey soil; So5: Reddish brown soil on basalt; So6: Yellowish brown soil on old alluvia; So7: Yellowish red soil on acid magma, sandstone and metamorphic rocks; So8: Eroded soil ; and So9: Humic soil on high mountain. c/ Soil depth (D)

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D1: > 100 cm; D2: 50-100 cm; and D3: < 50 cm. d/ Slopes (S) S1: < 15o; S2: 15-25o; S3: 25-35o; S4: > 35o. e/ Rainfall R1: > 2,000 mm; R2: 1,600-2,000 mm; R3: 1,200-1,600 mm; and R4: < 1,200 mm. Total land use units identified: 181, of which -At elevations below 300 m, there are 84 land use units which show the following characteristics: + Area of biggest unit: 142,600 hectares + Slopes mainly below 15 o; + Soils: reddish brown soil on basalt; grey soils and semi-arid grey soils: + Soil depths mainly above 50 cm; and + Rainfall: not high, mainly at the range of 1,600 mm per year, with less than 1,200 mm in some areas. -At elevations between 300 and 500 m above see level, there are 69 units showing the following features; + Slopes: variable with forest land being evenly distributed over all classes of slope and seemingly more on slope

classes of 15-25o and 25-35o than others; + Soils: mainly of yellowish red soils in acid magma, sandstone and metamorphic rocks; + Soil depths: mainly below 50 cm deep; and + Rainfall: mainly in the range of 1,200-1,600 mm, less often in the range of 1,600-2,000 mm -At elevations between 500 and 1,000 m, there are 36 units, in which the following characteristics are showing out: + Slopes: variable, but forest land being found to prevail on high slopes of above 35o; + Soils: mainly of yellowish red soils, with some soils being classified as humic soil on mountains; + Soil depths: soils less than 50 cm deep prevail; and + Rainfall: better rainfall; in the range of 1,600-2,000 mm and above 2,000 mm. -At elevations above 1,000 m, there are 4 land use units having high slopes over 35o and being endowed with yellowish red soils on acid magma and sandstone, and humic soils on mountains. In short, the Coastal South Central Vietnam is endowed with land use units showing out a wide range of physical conditions prevailing along the coast and in mountains running along and next to it. However, forest land productivity is not high, with low soil depths, medium land slopes and some localities of low annual rainfall tending to show some limitations to land farming. 2.5.3. Forest land use based on productivity assessment. Forest land productivity in the Coastal South Central Vietnam is not very high, because of its limitations. Besides the impacts of local climate in particular those from sea storms (typhoons) when acting simultaneously with rising tides thus causing catastrophic floods and seashore fully, there are isolated areas wheresevere drought can be noticed. Therefore, the establishment of a well managed protection forest system is very important; it is necessary to protect the vulnerable watersheds located next to the sea, to counter land slides especially along the main road No.1, to fix moving sand dunes, and to create more favourable microclimates in the semi-arid zone of the Region. Existing forests should be well protected and managed and timber extraction from these should be made with care following well-proved procedures and conservative allowable cut so to secure forest regeneration and growth. * The practice of agroforestry should be a “must”, and any departure from its sound principles can cause big losses to occur in the Region. Fortunately, good agroforestry models have been established by local farmers on sandy soils with the planting of casuarinas, Acacia auriculiformis in belts or strips, and of cashews in commercial plantations and with the management of home gardens in which tree crops, fruit crops, food crops and vegetables are grown in the most cosevative ways. Forest restoration through strict and well-planned protection is the most important practice because of the topographic, climatic and edaphic conditions of the Region and should be considered first, before any attempt of forest plantation is going to be carried out. · Forest tree crops to be used in the Coastal South Central Vietnam are not many, however the following species

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can be of interest: - Casuarinas can be used on coastal sandy soils to fix moving sand. Local farmers have got lots of knowledge and

field experience for the management casuarinas in their agro-forestry systems established on sandy soils, in particular in the provinces of Quang Nam and Da Nang. Casuarinas are also grown in Binh Thuan and Ninh Thuan, in the semi-arid zone of the Region, but much more care is needed to maintain a high survival and growth rate there; In particular, high seedlings, better use of soil water/moisture and soil dressing with casuarina-leaf compost... are the main points to secure reasonable success. On the other hand, provenance trials and other trial plantations of casuarinas on coastal sandy soils and on easy hillsides respectively are also carried out.

- A wide range of acacias, in particular Acacia auriculiformis and A. mangium, have also been tested at many

sites, with A. auriculiformis performing quite well on shallow soils showing outcrops at Hai Van pass. Moreover the Forest Science Institute of Vietnam (FSIV) has been testing with some drought-resistant acacias in Ninh Thuan and Binh Thuan and early results shows that Acacia torulosa, A. difficilis, A. tumida can grow well in semi-arid climate, while A. crassicarpa (vernacular Keo luoi liem) can do well on inland sandy soils.

- Among tropical pines, besides Pinus merkusii (vernacular Thong nhua), P.kesiya (venacular Thong ba la), P.

caribaea looks quite promising in particular in the provinces of Quang Nam, Da Nang and Quang Ngai. - Eucalyptus camaldulensis and E. tereticornis provenance Nghia Binh... are rated as interesting tree crops in the

region for the production of pulpwood and chips. - Indigenous timber species have not been cultivated on large scale in the region, and the usually used species are:

Dipterocarpus alatus (vernacular Dau rai) Cassia siamea (vernacular Muong den) and of course cinamons (vernacular cay Que), with the latter being grown for their bark on large scale at Tra Mi, Tra Bong in the province of .....

- Another tree crop now being in use is Anacardium occidentale (venacular Dieu or Dao lon hot). It is going to

spread in the Region, but the cultivar now being used at large seems to be degraded, and requires further plant breeding to get much more productive.

- Another point of much relevance to local farmers in the Region is that besides activities for forest protection, tree

species selection, and the practice of agroforestry, much more technical and economic assistance/investment is needed because local farmers are poor and farming activities on the marginal lands of the Region to protect and improve the existing the forests and environment always require important inputs to gain the desired success.

2.6. Tay Nguyen High Plateau Tay Nguyen High Plateau comprises the provinces of Gia Lai, Kon Tum, Dak Lak and Lam Dong. 2.6.1. Assessment of Forest land Productivity a) Slope (Table 42) - Forest land is found mainly on slopes of 25-35o (accounting for 44%), then next comes land with slopes of over

35o (28%). Forest land with lower slopes (less than 15o) is found mainly in Dak Lak (27%), while that with higher

slopes (15-25o) appears to be distributed quite evenly in all provinces. Gia Lai and Lam Dong are endowed mainly

with sloping forest land of 25-35o (50-52%), while in Kon Tum land with slopes above 35o accounts for 50%. - Forested land is mainly found on slopes varying from 25-35o to above 35o, of which that in Kon Tum and Lam

Dong provinces is relatively bigger. - Non-forested areas with slopes of less than 15o, 25-35o and above 35o are found with percentage of 6%, 11% and

6% respectively. b) Soil depths (Table 44) -Forest land on the High Plateau found to be endowed with soil depths of above 100 cm (47%) and below 50 cm (43%), with Dak Lak and Kon Tom having quite large area of land with soil depth above 100 cm (57-67%), while in Gia Lai soils less than 50 cm deep prevail (70%). -Forested areas with soil depth above 100 cm and less than 50 cm account for 39 % and 28% respectively, in particular forested areas with soil depth above 100 cm cover extensive areas in Dak Lak, Lam Dong and Kon Tum, with Dak Lak being endowed with 62%; with regard to soils less than 50 cm deep, the situation of almost the same in all provinces except Dak Lak. -Non-forested areas with soil depths less than 50 cm, and above 100 cm are noticed with percentages of 14% and 8% respectively. In particular, in Gia Lai province one can find non-forested lands with soil depths of less than 50 cm reaching a high percentage (35%).

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c/ Soil texture (Table 45)

-Forest soils on the High Plateau are of heavy and sandy textures (63 and 22% respectively). One can find heavy soils in Lam Dong, Kon Tum and Gia Lai (90%). But in Dak lak province, there are extensive areas of soils of sandy texture (41%). -Forested lands with heavy soils account for 49% of the total, of which larger areas of same (65% of the total) can be found in Lam Dong and Kon Tum. Forested areas with lighter soil texture (22% of the total/on the average) can be found mainly in Dak Lak where they occur with a higher percentage of 41%. -Non-forested areas are found mainly on forest soils of heavy /medium textures; however in terms of acreage, they are not important (2-14%).

d/ Organic matter content (Table 43)

-The point is forest soils in the Region are very rich/rich in humus, accounting for 60%; soils medium and poor in humus account for 26% and 7% of the total respectively. There is not much difference between provinces in term of organic matter content in soils; however Lam Dong is famous for its soils rich in humus occurring on extensive areas (45% of the total). -Forested lands endowed with soils very rich, and medium in humus content account for 26.5%, 32% and 26% respectively. The distribution of these soils follows the same pattern in almost all provinces, with only Dak Lak is outstanding for its soil very rich in humus covered with close forests. -Non-forested areas with soils medium in humus can be found with a percentage of 11% for the whole region; these are noticed mainly in Gia Lai, Kon Tum and in particular in Lam Dong where non-forested areas with soils very rich in humus reach a quite high percentage of 13.7%.

e/ General assessment based on the four component factors (Table 46)

-Forest land of grade 3 (medium) and grade 2 (good) account for 57% and 39% respectively, reaching 96% of the total; in particular, forests land of grade 2 (good) in Dak Lak amounts to 51%, while in other provinces the same can vary from 26 to 39%. Gia Lai, Kon Tum and Lam Dong are well endowed with forest land of grade 3 (medium), amounting to over 60%. Forested land of grade 2 and 3 is distributed evenly in all provinces with an average of 33-39%, except for Dak Lak where forested land of grade 2 amounts to 49%. Forested land of various grades in the provinces does not differ very much from each other, except for Dak Lak. -Non-forested areas of medium grade (grade 3) account for 18% on the average, of which those in Gia Lai and Kon Tum appear to be more extensive, varying from 19 to 25%; in other provinces, they vary within a narrower range (13 to 15%). In short, forest land on the High Plateau of Tay Nguyen can be rated as of grades 2 and 3, but most of them are under forest vegetation. Good to medium soil productivity there can be confirmed through the presence of deep soils and soils rich in humus, with some of them being very rich and rich in humus. The main limitations found are: high slopes, heavy soil texture and the aridity of the region, all of which can have strong impacts on land uses in particular when drought-sensitive crops are used. 2.6.2/ Identification of land use units The identification is made based on the following factors: a/ Elevations (H) H1: < 300 m; H2: 300-500 m; H3: 500-1.000 m; and H4: > 1,000 m. b/ Soil Group or Types (So): So1: Grey soil;

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So2: Black soil; So3: Violet brown and reddish brown soil on basalt; So4: Yellowish brown soil on basalt; So5: Yellowish red soil on acid rocks and schists; So6: Yellowish red soil on acid rocks and sandstone; So7: Yellowish brown soil on old alluvium; So8: Yellowish brown humic soil on basalt; So9: Reddish yellow humic soil on basalt; So10: Yellowish humic on sandstone; and So11: Eroded soil. c/ Slopes (S) S1: < 15o; S2: 15-25o; S3: 25-35o; S4: > 35o; d/ Soil depth (D) D1: > 100 cm; D2: 50-100 cm; and D3: < 50 cm. e/ Rainfall (R) R1: > 2,400 mm; R2: 2,000-2,400 mm; R3: 1,600-2,000 mm; and R4: < 1,600 mm. Total land use units identified: 253 landuse units -At elevations below 300 m asl, there are 68 land use units characterized by: slopes of less than 15o prevailing to be

followed by some of 15-25o and 25-35o; reddish/yellowish soils and grey soils developed on acid magmas and sandstones; soil depths being evenly distributed in their three classes; and rainfalls ranging from above 1,600 mm to above 2,400 mm. -At elevations between 300 and 500 m, there are 79 land use units with: slopes prevailing in the range of 25-35o; soil types the same as above plus reddish brown soils and greyish brown soils developed on basalt; soil depths ranging from less than 50 cm to above 100 cm (the latter prevailing). -At elevations between 500 and 1,000 m, there are 73 land use units being well characterized by slopes of 25-35o and

above 35o prevailing; soils of So 5, So 6 and So 9 types soil depths mostly in the range of above 100 cm; and rainfalls quite scarce with some areas having a rainfall of less than 1,600 mm. -At elevations above 1,000 m above sea level, there are 36 land use units where slopes are not of the range from 25-35o

and above 35o, soils are of the types of So 5, So 6 and So 9, soil depths are quite good with over 100 cm, and rainfall less than 1,600 mm. 2.6.3/ Forest land use based on productivity assessment. Tay Nguyen High Plateau is endowed with large forest resource, because almost 60% percent of its forest land is rated as of grades 2 and 3. Climatic and edaphic conditions in the Region are all favourable for the growth and development of forest tree species, yielding stands of 500-600 cu.m/ha of standing stock the average value of which being 300-400 cu.m/ha. Many prime timber species can yield trees of over 60 cm dbh when mature. On the other hand, there are rich stands of Pinus Kesiya (vernacular Thong ba la) thriving very well in Lam Dong and the open forests of Dipterocarpus which although being located in semi-arid areas and threatened by frequent forest fires, can yield a quite large amount of timber as they are growing on flat terrains in a peneplain. Therefore for many, the forests and forest land of Tay Nguyen are valuable assets, for the maintenance of which better management and protection to continually increase their resource is not only badly needed but also always economically feasible. The point is to develop better method for timber logging to secure forest regeneration, to adapt appropriate silvicultural operations for forest maintenance and to control forest fires in particular in areas where open

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forests of Dipterocarps occur, because the soils there are very shallow and as a result quite vulnerable. Fire control is also needed in extensive areas where Pinus Kesiya (vernacular Thong ba la) occurs naturally. However, the problem of better fire management here should be studied with care because fire in particular surface fire as an ecological factor can do something good for pine regeneration through the removal of a thick layer of litter under pines so that their seeds can go direct to the soil for prompt germination. Managing that process with care can help Pinus Kesiya regenerate continually and yield sustained timber production over time. Parallel with this are the poor timber production and the low tree density of many natural pine stands, which also requires in depth research and urgent improvements. Other tree species mainly used for forest plantation and regeneration in the High Plateau of Tay Nguyen besides Pinus kesiya are: resinous pine (P. merkusii), P. caribeae, Acacia auriculiformis, A. mangium, eucalypts...They can grow better on soils developed on acid magmas than the so-called degraded basaltic soils, because of a drier local climate prevailing on areas with degraded basaltic soils, which under the present setting have their physical and chemical properties severely destroyed (Do Dinh Sam, Ngo Que, 1993, 1999). For instance, P. kesiya... growing on degraded basaltic soils can yield only 2 cu.m/ha/annum, which on soils developed on acid magma, in particular at Kong Plong (in Kon Tum) it can produce up to 9-16 cu.m per hectare and per year. The same can be said of Eucalyptus camaldulensis, which on soils developed on acid magma can give a quite high yield of 10-14 cu.m/ha/annum and even higher. Even with A. auriculiformis, its yield on degraded basaltic soils can never go up to over 5-8 cu.m per hectare and per year. At higher elevations (1,500 asl), trial and research so far carried out point to the fact that some tree species, among them Eucalyptus microcoris, E. saligna and Acacia mangium...perform very well there. Agroforestry has been developed and practised in the Region for the establishment of forest tree crops (mainly Teak (Tectona grandis)) and a number of agricultural cash crops (such as coffee, pepper and rubber trees). However for better protection of all commercial plantations established through agroforestry practice and of the environment as well, it is always advisable, in the Region, to create windbreaks, firebreaks, and use as many nitrogen-fixing legumes such as Cassia siamea (vernacular Muong den) as possible. Under the present settings, the most important thing is to have an appropriate master plan for a better coordinated management of the land resources of the Region. It is advisable to have better demarcation of forest land for it to be managed with care on a long term basis, thus avoiding land clearing on vulnerable areas for the cultivation of agricultural cash crops, which can be very productive on a short term basis, but which may cause the land to degrade dramatically to the prejudice of many other people at large. On the other hand, better protection and management of all existing natural and man-made forests, and wise and careful establishment of forest plantations using improved cultivars and cultigens for the production of prime timber, pulp and chips for industries etc. should be carried out steadily and patiently. Moreover, swiddening as practised by ethnic minorities should be first studied and tackled step by step through assignment of “Ray” to local farmers and technical extension activities/projects to help them shift from the cultivation of upland rice to that of perennial cash crops, fruit crops and tree crops as the land is rated as quite suitable a wide range of farming systems. In short, soil conservation in its largest meaning to cover both agriculture and forestry land farming systems not excepting the practice of soil conservation on denuded mountain and hillsides meant for forest plantation, for the maintenance of the present land resource and its improvements is the most important task in Tay Nguyen nowadays. Parallel with is another programme for the conservation of all plant and animal gene resources of the Region to back up all efforts for natural resources protection. 2.7/ The East South Vietnam The East South Vietnam comprises the provinces of Song Be (now divided into Binh Phuoc and Binh Duong), Dong Nai, Tay Ninh, Ba Ria Vung Tau and Ho Chi Minh City

2.7.1/ Assessment of productivity made on the following factors:

a/ Slopes (Table 47) In the East South Vietnam, the lie of forest land in terms of slopes can be described follows: + Land with slopes less than 15o, of 15-25o and above accounts for 49%, 24% and 8% respectively: Only in Song Be is land of less than 15o of slope extending over a smaller of area (26%); in other provinces, it always prevails going up to 67-100%. Song Be on the contrary has a bigger area of land with higher slopes (31-32%). + Forested land with slopes of less than 15o and 15-25o accounts for 41% and 21% of the total respectively, of which the provinces of Dong Nai, Tay Ninh and Vung Tau appear to have over 62-65% of their forested land on slopes of the above-mentioned classes. And almost the same percentage of forested land (24-32%) can be found separately on the three slope classes in Song Be.

Page 19 of 22

+ Non-forested areas are distributed more or less evenly in all classes of slopes b/ Soil depth (Table 48) -In the Region, soil depths of above 100 cm and of less than 50 cm are found with 60% and 20% of the total forest land area respectively; however Dong Nai is less favourable with soil depth above 100 cm being found with a lower percentage of 26%, and soil depth of less than 50 cm being noticed with a percentage of 44%. In the province one can also find large areas of lands bearing pronounced lateritic characteristics, not excepting those under natural forests. -More than 50% of forested lands are found on soil above 100 cm depth; but in Dong Nai forested lands with such depths are lower (only 14%), and nearly a half of its forested lands (or more precisely 44%) can be found on soil less than 50 cm deep. -Non-forested lands are found mainly on soils above 100 cm and less than 50 cm deep with the same percentage, but in Dong Nai most non-forested land is on deep soils (above 100 cm). c/ Soil texture (Table 49) -Forest land in the East South Vietnam is mainly of heavy texture (70% of its lands), with loamy soils accounting for only 23%, except for Tay Ninh where loamy soil can be found with a percentage of 73%. Other provinces, cities such as Song Be and Ho Chi Minh City have got a high percentage (as high as 96-97%) of soils with heavy texture. Sandy soil is mainly found (at a percentage of 30%) at Vung Tau. -Forested land with clayey soils and loamy soil accounts for 56% and 19.7% respectively; with Song Be having most of its forests (87%) growing on clay, and Tay Ninh and Dong Nai having more than 50% of their forests growing on loams. -Non-forested lands (13%) are found mainly on clays. d/ Organic matter content (Table 50) -With regard to organic matter content in forest soils of the Region, the following can be said: + Soils rich in humus cover an area of 51% of the total; they are found mainly under natural forests; + Soil medium in humus account for an area of 40%; and + Tay Ninh and Song Be are provinces where soils rich in humus can be found over extensive areas of natural forests (reaching 60-66% of the total). -More than 46% of forested land are rich in humus and the other 29% medium in humus. -Non-forested areas are medium in humus content (10%), those rated as poor in humus amount to 3%, and those rich in humus accounting for 4.3%. In short, soil rich/medium in humus are found mainly under forest vegetation, in particular natural forests. e/ General assessment of forest land in the Region (Table 51) Based on the four factors used for general assessment, one can say that: -Forest land in the East South Vietnam is rated as of grade 2 mainly (accounting for 57% of the total), giving fair productivity and showing a few limitations when used; coming next is forest land of grade 3(amounting of 32%). Only at Tay Ninh, can forest land of grade 1 (10% of the total), can be found, they are mainly under forests. Other provinces such as Dong Nai, Song Be, Vung Tau are endowed with land of grade 2 covering almost the same percentage in each province, the same can be said of land of grade 3. -Forested land of grade 2 and grade 3 accounts for 50% and 22% of the total respectively, with land of grade 2 prevailing in the provinces of Song Be, Dong Nai, Vung Tau (58-65%), and land of grade 3 showing the same pattern in two provinces. -Non-forested, lands are rated mainly as of grade 2, with a few particulars being found in Tay Ninh where land of grade 1 amounts to 20% and in Vung Tau where land of grade 3 reaches a percentage of 22%. In short, forest land in the Eastern Region of South Vietnam is mainly of grades 2 and 3, totalling 89% of the total, in which those of grade 2 account for 60%, showing that forest land there is favourable for forestry development. However, most lands of grade 2 are under forest; only is some land of grade 3 available for reforestation, most of it is found in Vung Tau. The main points of interest are: -Flat terrain conditions, with slopes under 15o prevailing; -Deep soils (60% of the forest land endowed with deep soils of above 100 cm); -Soil texture loamy soils favourable to tree crop growth and development; -High amount of soil organic matter (more than a half of the land area endowed with rich humus content). -Soil types: soil developed on basalts and grey soils suitable for the cultivation of a wide range tree crops, cash crops

Page 20 of 22

and others. 2.7.2/ Land use unit identification The identification is made based up on: a/ Altitude (H) H1: < 100 m; H2: 100-300 m; and H3: > 300 m. b/ Soil group or types (So) So1: Coastal sandy soil;

So2: Mangrove saline soil; So3: Acid sulphate soil; So4: Grey soil; So5: Gley grey soil; So6: Brownish yellow soil on old alluvium; So7: Red soil, reddish violet soil on basalt; So8: Yellowish red soil on schist; So9: Yellowish red soil on granite; So10: Colluvial soil on basalt; and So11: Colluvial soil on other rocks. c/ Slopes (S) S1: < 15

o S2: 15-25o; and S3: > 25

o d/ Soil depths (D) D1: > 100 cm; D2: 50-100 cm; and D3: < 50 cm. e/ Rainfall (R) R1: > 2,000 mm; R2: 1,600-2,000 mm; and R3: < 1,600 mm.

Total land use units identified: 102, descriptions of which follow: -At elevations below 100m asl, there are 64 land use units characteristics by: slopes below 15o. three soils types (Grey and brownish yellow soils on old alluvia and reddish brown soil on basaltic parent materials) prevailing; soil depths of above 100 cm and 50-100 cm covering extensive areas; rainfall ranging from less than 1,600 mm to 1,600-2,000 mm. -At elevations between 100 and 300 m, there are 36 land use units having; + Slopes: less than 15o and 15-25o; + Soils: 3 types as above plus yellowish red soils developed on sandstone, granites and metamorphic rocks. + Soil depths; ranging from 50 cm to 100 cm; and + Rainfall: mainly of the order of 1,600-2,000 mm and in some areas over 2,000 mm. -At elevations above 300 mm, there are only four (4) land use units being endowed with grey and reddish brown soil developed on basalt; soil depths from moderate to high; and rainfalls exceeding 2,000 mm. The key features found in most land use units here are: moderate slopes soil depths ranging from medium to high (above 100 cm); rainfalls abundant ranging from 1,600-2,000 mm and above with only a few areas being less than 1,600 mm of rainfall; all rated as favourable for land farming in particular when using agroforestry practice. 2.7.3/ Forest land use based on productivity assessment The forest land productivity assessment made points to the fact that conditions in the East South Vietnam are most favourable to forestry development, because of its large area of forest land with gentle slopes and deep soils.

Page 21 of 22

Therefore, conditions are available there to carry out intensive methods of forest land farming, vizo: -Intensive forest management to increase the yields of both natural and man-made forests; and -Wide application of agroforestry practice and systems. Of course, for the development of protection forests and an effective protective system in the vulnerable watershed areas of the Region, stricter protection should be adopted based on well delineated protective areas, enrichment planting and regular surveillance so that the system can work most efficiently and effectively. In production forests, the main points are to raise the yields of all forest stands involved through: improved timber extraction systems combined with silvicultural operations to secure good natural regeneration, well -planned thinnings of non-target timber species to favour the growth and development of prime timber saplings and standards and increase the population of the most desirable timber regrowths and well-organized weading and pruning to help promote both natural regeneration and tree growth. Whenever, natural regeneration turns up late, wise and well-arranged enrichment planting can be applied with fallibility so to create mixed stands of regrowths and planted seedlings either in strips, patrishing or mosaics so to secure better yields for the felling cycles to come. Plantations can be carried out using fast-growing species for the production of pulpwood for the paper making industries, but emphasis should be laid upon biodiversity, rotation of crops and integrated pest management so to avoid the catastrophic impacts of monoculture (for instance that of eucalyptus or pines...) over extensive areas. For teak plantations, it is advisable to carry out more intensive plant breeding from scratch to select the best provenances and obtain adequate big amount of improved seeds... to help planters get better incomes when they are willing to manage their plantations correctly following well proven technics. By now, teak is planted extensively; it yields low production for want of improved seeds and good management . Other promising indigenous timber species are: Hopea odorata (vernacular Sao den) and Dipterocarpus alatus (vernacular alatus). But success may come only when the cropping systems produce plant cover. The cover is needed not only to protect the soil from erosion and help preserve soil structure, but also to contribute to the growth and development of the target species. Lots of successful models established in the Region point to that reality. Agroforestry is also well adapted to the physical conditions of the land and the farming habits of local people, who usually grow cashew nut trees, coffee and even ground nut mung bean, popaye... in combination with tree crops, in particular on areas endowed with reddish brown soils developed on basalts and grey soils. The system can have further improvements to turn it into tree gardens, home gardens, forest gardens to produce better results and incomes. In short, forested land in the East South Vietnam is best for timber and other forest product production; and all -non-forested areas there are also suitable for establishment of productive agroforestry systems. Investments for forestry development in the Region are cost effective. Back to contents Next>>

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Table 7: Land slope classes in the North West

Table 8: Distribution of sloping forest land in the North West

Table 9: Soil depth classes in the North West

Table 10: Distribution of forest land with different soil depths in the North West

Table 11: Forest soil texture classes in the North West

Table 12: Distribution of forest land with different soil texture classes in the North West

Table 13: Forest soil organic matter content classes in the North West

Table 14: Distribution of forest land with different soil organic matter contents in the North West

Locality Class 1 <15o Class 2 (15-25o) Class 3 (25-35o) Class 4 (>35o) Rocky mounatin S (ha) % S (ha) % S (ha) % S (ha) % S (ha) %

Region 160,000 4.0 257,500 6.4 787,500 19.6 2,685,000 66.7 137,500 3.4 Lai Chau 12,500 0.7 90,000 4.7 302,500 15.9 1,457,500 79.4 45,000 2.4 Son La 27,500 1.8 87,500 5.6 457,500 29.3 950,000 60.8 40,000 2.6

Hoa Binh 120,000 21.5 80,000 14,.3 27,500 4.9 277,500 49.8 52,500 9.4

Locality Class 1 (< 15o) (ha/%) Class 2 (15-25o) (ha/%) Class 3 (25-35o) (ha/%) Class 4 (>35o) (ha/%) Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Region 66,700

2.5 11,890

0.4 54,810

2.1 133,390

2.1 15,350

0.6 118,030

4.4 523,800

19.6 57,610

2.2 466,190

17.4 1,950,110

72.9 389,140

14.5 1,560,970

58.4 Lai

Chau 7,850

0.6 0 7,850

0.6 51,000

3.6 0 51,000

3.6 225,610

16.1 25,390

1.8 200,200

14.3 1,118,260

79.7 200,290

14.3 917,970

65.4 Son La 3,920

0.4 0 3,920

0.4 47,080

4.6 3,470

0.3 43,610

4.3 282,500

28.0 17,360

1.7 265,140

26.3 672,930

66.8 114,500

11.4 558,370

55.4 Hoa Binh

54,930 20.7

11,890 4.5

43,040 16.2

35,310 13.3

11,890 4.5

23,420 8.8

15,690 5.9

14,860 5.6

830 0.3

158,920 60.0

74,290 28.0

84,630 32.0

Locality

Classes 1 & 2 (>100 cm)

Class 3 (50-100 cm)

Class 4 (< 50 cm)

Rocky mountain

S (ha) % S (ha) % S (ha) % S (ha) % Region 1,160,000 28.8 1,827,500 45.5 902,500 22.4 137,500 3.4

Lai Chau 445,000 23.3 930,000 48.8 487,500 25.6 45,000 2.4 Son La 500,000 32.0 687,500 44.0 335,000 21.4 40,000 2.6

Hoa Binh 215,000 38.6 210,000 37.7 80,000 14.3 52,500 9.4

Class 1 & 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality Total Forested Non-

forested Total Forested Non-forested Total Forested Non-

forested Region 716,080

26.8 104,900

3.9 611,180

22.9 1,283,050

48.0 255,440

9.5 1,027,610

38.5 674,870

25.0 113,660

4.2 561,210

20.8 Lai Chau 313,900

22.3 39,490

2.8 274,410

19.5 700,380

49.5 115,660

8.2 584,720

41.7 388.440

27.7 70,530

5.0 317,910

22.7 Son La 300,160

29.8 20,830

2.1 279,330

27.7 468,880

46.6 83,320

8.3 385,560

38.3 237,390

23.6 31,240

3.1 206,150

20.5 Hoa Binh 102,020

38.5 45,580

16.8 57,440

21.7 113,790

42.9 56,460

21.3 57,330

21.6 49,040

18.5 11,890

4.5 37,150

14.0

Classes 1 & 2: Loam Class 3: Clay Class 4: Loamy sand Rocky mountain Locality S (ha) % S (ha) % S (ha) % S (ha) % Region 1,672,000 41.5 48,500 12.0 1,732,500 43.0 137,500 3.4

Lai Chau 805,000 42.2 9,500 5.0 962,500 50.0 45,000 2.4 Son La 662,500 42.4 24,750 15.8 612,500 39.2 40,000 2.6

Hoa Binh 205,000 38.6 14,250 25.6 157,500 38.3 52,500 9.4

Classes 1 & 2: Loam (ha/%) Class 3: Clay (ha/%) Class 4: Loamy sand (ha/%) Locality Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Region 1,155,530

43.2 152,610

5.7 1,002,420

37.5 258,960

6.9 55,840

2.1 203,120

4.8 1,259,410

47.0 265,550

9.9 993,860

37,18 Lai Chau 616,020

34.9 64,880

4.6 551,140

30.3 56,890

4.0 2,820

0.2 54,070

3.8 729,810

52.0 157,980

11.0 571,830

41.0 Son La 435,530

43.2 52,070

5.2 383,460

38.0 127,520

12.6 17,360

1.7 110,160

10.9 443,280

44.0 65,960

6.5 377,320

37.5 Hoa Binh 103,980

39.2 35,660

13.4 68,320

25.8 74,550

28.1 35,660

13.4 38,890

14.7 86,320 32.60

41,610 15.7

44,710 16.9

Locality Class 1 Class 2 Class 3 Class 4 Rocky mountain S (ha) % S (ha) % S (ha) % S (ha) % S (ha) %

Region 245,000 6.1 1,462,500 36.3 1,505,000 26.0 1,132,500 28.1 45,000 3.4 Lai Chau 162,500 8.5 805,000 42.2 407,500 21.4 487,500 25.6 40,000 2.4 Son La 60,000 3.8 582,500 37.3 447,500 28.6 432,500 27.7 40,000 2.6

Hoa Binh 22,500 4.0 75,000 13.5 195,000 35.0 212,500 38.1 52,500 9.4

Page 1 of 6

Table 15: General assessment of productivity of forest land in the North West

Table 16: Distribution of forest land of the North West assessed based upon four basic factors

Table 17: Distribution of sloping forest land in the North Central Region (in ha/%)

*Former administrative unit

Table 18: Distribution of forest land with different soil depths in the North Central ( in ha/%)

* Fomer administrative unit

Table 19: Distribution of forest land with different soil texture classes in the North Central (in ha/%)

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Region 169,640

6.3 116,350

4.4 53,290

1.9 1,157,480

43.3 223,380

8.4 934,100

34.9 618,890

23.1 86,600

3.2 532,290

19.9 727,990

27.3 47,670

1.9 680,320

25.4 Lai

Chau 98,090

7.0 84,630

6.0 13,460

1.0 670,950

47.8 112,840

8.0 558,110

39.8 276,620

19.7 11,280

0.8 265,340

18.9 357,560

25.5 16,930

1.3 340,130

24.2 Son La 47,080

4.6 13,980

1.4 33,190

3.3 435,530

43.3 65,960

6.6 369,570

36.7 243,270

24.2 27,770

2.8 215,500

21.4 280,550

27.8 27,770

2.7 252,780

25.1 Hoa Binh

24,470 9.2

17,830 6.7

6,640 2.5

51,000 19.2

44,580 16.8

6,420 2.8

99,000 37.4

47,550 17.9

51,450 19.5

90,380 34.2

2,970 1.2

87,410 33.0

Locality Grade 1 Grade 2 Grade 3 Grade 4 Rocky mountain S (ha) % S (ha) % S (ha) % S (ha) % S (ha) %

Region 5,000 0.1 725,000 18.0 2,527,500 62.8 632,500 15.7 137,500 3.4 Lai Chau 0 247,500 13.0 1,225,000 64.2 390,000 20.4 45,000 2.4 Son La 0 300,000 19.2 1,022,500 65.4 200,000 12.8 40,000 2.6

Hoa Binh 5,000 0.9 177,500 31.8 280,000 50.2 42,500 7.6 52,500 9.4

Grade 1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Total Forested Non-

Forested Region 94,170

3.5 41,950

1.5 52,220

2.0 427,690

16.0 60,170

2.3 367,520

13.7 1,691,120

36.2 291,430

10.9 1,399,690

25.3 461,020

17.2 83,270

3.1 377,750

14.1 Lai

Chau 31,390

2.2 2,820

0.2 28,570

2.0 176,570

12.6 14,100

1.0 162,470

11.6 900,490

64.2 138,230

9.9 762,260

54.3 294,270

21.0 73,350

5.2 220,920

15.8 Son La 21,580

2.1 3,470

0.8 18,110

1.8 168,720

16.7 10,410

1.0 158,310

15.7 688,610

68.4 114,560

11.4 574,050

57.0 127,520

12.7 6,950

0.7 120,570

12.0 Hoa Binh

41,200 15.5

35,660 13.4

5,540 2.1

82,400 31.0

35,660 13.4

46,740 17.6

102,020 38.5

37,640 14.6

63,380 23.9

39,230 14.8

2,970 1.1

36,260 12.7

Class1 (in ha/%) Class 1 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Ha

Giang 25,080

5.2 23,750

5.0 1,330

0.2 61,870

13.0 23,750

5.0 38,120

8.0 138,800

29.1 66,500

13.9 72,300

15.2 250,840

52.6 104,500

21.9 146,340

30.7 Tuyen Quang

13,380 4.6

12,750 4.4

630 0.2

63,550 22.1

61,250 21.3

2,300 0.8

107,020 37.2

101,750 35.4

5,270 1.8

103,680 36

85,500 29.7

18,180 6.3

Yen Bai 8,360 1.7

8,250 1.6

110 0.1

68,560 13.9

10,750 2.2

57,810 11.7

157,190 31.9

42,750 8.7

114,440 23.2

287,530 58.5

85,500 17.4

202,030 41.1

Lao Cai 48,500 9.3

14,250 2.7

34,250 6.6

93,650 18.0

57,750 8.2

50,900 9.8

170,570 33.0

66,500 12.8

104,070 20.2

205,680 39.7

61,750 11.9

143,930 27.8

Vinh Phu*

46,820 34.5

19,000 14.0

27,820 20.5

5,020 3.4

5,020 3.4

40,130 29.6

14,250 10.5

25,880 19.1

43,770 32.2

14,750 10.9

29,020 21.3

Total 142,140 7.4

78,000 4.1

64,140 3.3

292,650 15.3

138,500 7.2

154,150 8.1

612,910 32.1

291,750 15.2

321,160 16.9

891,500 46.7

352,000 18.4

539,500 28.3

Classes 1 &2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

Forested S Forested Non-

Forested S Forested Non-

Forested Ha Giang 152,170

32.6 24,750

5.2 127,420

27.4 227,430

48.7 114,000

23.9 113,430

24.8 96,990

18.7 79,750

16.7 17,240

2.0 Tuyen Quang

148,830 51.7

128,750 44.8

20,080 6.9

113,710 39.5

108,500 37.7

5,210 1.8

25,090 8.8

24,000 8.3

1,090 0.5

Yen Bai 279,270 56.8

66,500 13.5

212,770 43.3

187,290 38.0

66,500 13.5

120,790 24.5

25,080 5.2

14,250 2.9

10,830 2.3

Lao Cai 172,240 33.2

61,750 11.9

110,490 21.3

254,180 49.0

109.250 21.2

144,930 27.9

91,980 17.8

14,200 2.7

77,730 15.1

Vinh Phu* 61,870 45.6

32,750 25.5

29,120 20.1

46,820 34.5

24,000 17.7

22,820 16.8

27,050 19.9

27,050 19.9

Total 814,380 42.6

305,500 16.0

508,880 26.6

829,430 43.4

422,250 22.1

407,180 21.3

266,190 14.0

132,250 6.9

133,940 7.1

Classes 1 & 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

Forested S Forested Non-

Forested S Forested Non-

Forested Ha Giang 454,850

95.4 213,750

44.8 241,100

50.5 21,740

4.6 4,750

0.9 16,990

3.7

Page 2 of 6

*Former administrative unit

Table 20: Distribution of forest land with different soil organic matter content in the North Central Region (in ha/%)

* Former administrative unit

Table 21: Distribution of forest land of the North Central Region assesses grades (in ha/%)

* Former administrative unit

Table 22: Land slope classes in the North East

*Former administrative unit

Table 23: Distribution of sloping forest land in the North East

Tuyen Quang 280,940 97.7

261,250 75.2

19,690 22.5

6,690 2.3

6,690 2.3

Yen Bai 489,970 99.7

147,250 29.9

342,720 69.8

1,670 0.3

1,670 0.3

Lao Cai 516,730 99.7

185,250 35.7

331,480 64.0

1,670 0.3

1,670 0.3

Vinh Phu* 112,040 85.2

47,750 35.2

64,280 47.3

23,700 17.5

23,700 17.5

Total 1,854,530 97.1

855,250 44.8

999,280 52.3

55,470 2.9

4,750 0.21

50,720 2.7

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Ha Giang 31,770

6.7 30,750

6.58 1,020 0.02

212,380 44.6

164,000 31.4

48,380 10.2

172,240 36.1

23,750 5.0

148,490 31.1

60,200 12.6

60,200 12.6

Tuyen Quang

53,510 18.6

52,250 18,16

1,260 0.04

78,600 27.3

78,500 27.3

100

118,730 41.3

110,500 38.4

8,230 2.9

36,790 12.8

20,000 7.0

16,790 5.8

Yen Bai 83,610 17.0

83,500 16.99

110 0.01

197,330 40.1

59,000 12.0

138,330 28.1

183,950 37.4

4,750 0.9

179,200 36.5

26,750 5.4

26,750 5.4

Lao Cai 100,340 19.4

100,250 19.39

90 0.01

200,670 38.7

85,000 16.4

115,670 22.3

214,050 41.3

214,050 41.3

3,340 0.6

3,340 0.6

Vinh Phu*

13,380 10.8

13,300 10.72

80 0.08

46,820 34.4

34,450 25.4

12,370

50,170 44.1

50,170 44.1

25,370 1.9

25,370 1.9

Total 282,610 15.0

280,050 14.96

2,560 0.04

735,800 39.0

420,950 22.0

314,850 17.0

739,140 39.1

139,000 6.8

600,140 32.3

152,450 6.9

20,000 0.1

132,452 6.8

Grade 1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Ha Giang 13,380

2.8

13,080 2.7

300 0.1

326,090 68.4

181,700 38.1

144,390 30.3

137,120 28.8

23,750 5.0

Tuyen Quang

8,360 2.9

8,250 2.8

110 0.1

247,490 86.0

246,250 85.6

1,240 0.4

31,780 11.0

6,750 2.3

Yen Bai 8,360 1.7

8,200 1.66

160 0.04

433,110 88.1

134,300 27.3

298,810 60.8

50,170 10.2

4,750 1.0

Lao Cai 15,050 2.9

14,250 2.7

800 0.2

419,730 81.0

166,250 32.1

253,480 48.9

83,620 16.1

4,750 0.1

Vinh Phu*

13,350 11.8

13,000 9.6

380 2.2

91,970 80.9

34,750 25.6

57,220 55.3

30,390 7.3

Total 58,530 3.0

56,750 2.97

1,780 0.03

1,518,390 79.5

763,256 40.0

755,140 39.5

333,080 17.5

40,000 2.1

Class 1 < 15

o Class 2 (15-25o) Class 3 (25-35o) Class 4 ( > 35o) Limestone mountain Locality S (ha) % S (ha) % S (ha) % S (ha) % S (ha) % Region 170,000 5.3 232,500 7.3 375,000 11.7 1,967,500 61.5 455,000 14.3 Cao Bang Lang Son Bac Thai* Quang Ninh Ha Bac*

0

7,500

25,000

17,500

120,000

0

0.2

3.8

4.1

35.3

2,500

32,500

112,500

52,500

32,500

0.3

3.8

17.2

12.4

9.6

35,000

117,500

87,500

97,500

37,500

3.8

13.7

15.4

22.9

11.0

600,000

580,000

380,000

275,000

150,000

65

67.6

58.0

60.0

44.4

285,000

120,000

50,000 - -

30.9

14.1

7.7 - -

Class 1 (in ha/%) Class 2 (in ha/%) Cap 3 (in ha/%) Class 4 + Limestone ( ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 37,400

2.2 5,770

0.3 31,630

1.9 52,380

3.1 30,920

1.8 21,460

1.3 142,950

8.5 38,800

2.3 104,150

6.2 1,438,270

86.0 497,510

29.7 940,760

56.3

Cao Bang - - - - - - 1,780 3.7

6,300 1.3

11,510 2.4

465,010 96.3

99,470 20.6

365,540 75.7

Bac Thai* 6,300 2.2

5,770 2.0

530 0.2

20,460 7.1

17,310 6.0

3,150 1.1

22,040 7.7

11,540 4.0

10,500 3.7

237,680 83.0

103,860 36.0

133,820 47

Lang Son - - - 7,700 - 7,700 63,550 15,340 48,210 417,870 107,300 310,530

Page 3 of 6

*Former administrative unit

Table 24: Soil depth classes in the North East

*Former administrative unit

Table 25: Distribution of forest land with different soil depths in the North East

*Former administrative unit

Table 26: Forest soil texture classes in the North East

*Former administrative unit

Table 27: Distribution of forest land with different soil texture classes in the North East

*Former administrative unit

1.6 1.6 13.0 3.1 9.9 85.4 21.9 63.5 Quang Ninh

15,740 11.9

- 15,740 11.4

9,830 7.5

7,980 6.0

1,850 1.5

7,870 6.0

- 7,870 6.0

98,350 74.6

51,850 39.3

46,500 35.3

Ha Bac* 15,360 5.5

- 15,360 5.5

14,390 5.1

5,630 2.0

8,760 3.1

31,680 11.3

5,620 2.0

26,060 9.3

219,360 78.1

134,990 48.0

84,370 30.1

Locality

Classes 1 & 2 (>100cm) Class 3 (50-100cm) Class 4 (< 50cm) Limestone mountain

S (ha) % S (ha) % S (ha) % S (ha) % Region 670,000 20.9 735,000 23.0 1,340,000 41.9 455,000 14.3 Cao Bang Lang Son Bac Thai* Quang Ninh Ha Bac*

277,500

192,500

85,000

75,000

107,000

30.0

22.4

13.0

1.8

31.9

200,000

230,000

240,000

32,500

32,500

21.6

26.8

36.6

7.6

9.6

162,500

315,000

280,000

385,000

197,500

17.6

36.7

42.7

90.6

58.5

285,000

120,000

50,000 - -

30.9

14.1

7.7 - -

Classes 1 & 2 (>100cm) (in ha/%) Class 3 (50-100cm) (in ha/%) Class 4 (< 50cm) (in ha/%) Locality S Forested Non-forested S Forested Non-

forested S Forested Non-

forested

Region 433,570 25.9

67,260 4.0

366,310 21.9

475,520 28.4

167,060 10,0

308,460 18.4

761,870 45.6

333,680 20

428,190 25.6

Cao Bang 201,830 41.8

25,190 5.2

176,640 36.6

152,360 31.5

44,090 9.1

108,270 22.4

128,630 26.6

31,490 6.5

97,140 20.1

Bac Thai* 45,650 15,9

5,770 2.0

39,880 13.9

136,940 47.8

63,470 22.1

73,470 25.7

103,890 36.2

69,240 24.2

34,650 12.0

Lang Son 134,800 27.5

30,670 6.3

104,130 21.2

146,350 30.0

30,670 6.3

115,680 23.7

207,970 42.5

61,340 12.5

146,630 30.0

Quang Ninh 11,800 8.9

- 11,800 8.9

15,740 11.9

11,960 9.1

3,780 2.8

104,250 79.0

47,870 36.3

56,380 42.7

Ha Bac*

39,490 14.0

5,630 2.0

33,860 12.0

24,130 8.6

16,870 6.0

7,260 2.6

217,130 77.3

123,740 44

93,390 33.3

Loam ( Class 1 & 2) Clay (Class 3) Sandy soil (Class 4) Limestone Locality S (ha) % S (ha) % S (ha) % S (ha) % Region 1,595,000 49.9 127,500 4.0 1,020,000 31.9 455,000 14.3 Cao Bang Lang Son Bac Thai* Quang Ninh Ha Bac*

487,500

465,000

365,000

82,500

195,000

52.8

54.2

55.7

19.4

57.8

40,000

12,500

7,500 0 0

4.3

1.5

11.5 0 0

110,600

260,000

165,000

342,500

142,500

11.9

30.3

25.3

80.6

42.2

285,000

120,000

50,000 - -

30.9

14.1

7.7 - -

Loam (in ha/%) Clay (in ha/%) Sandy soil (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 954,340

57 216,740

13 737,600

44 73,240

4.4 17,310

10 55,930

3.4 u

38.5 333,950

20 309,830

18.5 Cao Bang 360,130

74.6 69,280

14.3 290,850

60.3 35,620

7.4 - 35,620

7.4 87,070

18.0 31,490

6.5 85,580

11.5 Bac Thai* 185,740

64.8 69,240

24.1 116,540

40.7 31,840

11.1 17,310

6.0 14,530

5.1 69,260

24.2 51,930

18.1 17,330

6.1 Lang Son 323,510

66.1 61,340

12.5 262,170

53.6 5,780

1.2 - 5,780

1.2 159,830

32.6 61,340

12.5 98,490

20.1 Quang Ninh 54,250

41.1 - 54,250

41.1 0 0 0 77,540

58.8 58,930

45.4 17,710

13.4 Ha Bac* 30,710

10.9 16,880

6.0 13,830

4.9 0 0 0 250,080

89.0 129,360

46.0 120,720

43.0

Page 4 of 6

Table 28: Forest soil organic matter content classes in the North East

*Former administrative unit

Table 29: Distribution of forest land with different soil organic matter contents in the North East

*Former administrative unit

Table 30: General assessment of productivity of forest land in the North East

*Former administrative unit

Table 31: Distribution of forest land of the North East assessed into grades

*Former administrative unit

Table 32: Distribution of sloping forest land in the Coastal North Central Vietnam

Class 1 Class 2 Class 3 Class 4 Limestone Locality S (ha) % S (ha) % S (ha) % S (ha) % % Region 90,000 2.8 407,500 12.8 1,300,000 40.8 930,000 29.2 14.3 Cao Bang Lang Son Bac Thai* Quang Ninh Ha Bac*

47,500

10,000

10,000

22,500 0

5.1

1.2

1.5

5.3 0

80,000

92,500

72,500

140,000

22,500

8.7

10.9

11.2

33,1.

6.6

222,500

385,000

325,000

170,000

197,500

24.1

45.3

50.2

40.2

58.1

287,500

242,500

190,000

90,000

120,000

31.2

25.6

29.3

21.3

35.3

30.9

14.1

7.7 - -

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 & 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 147,450

8.8 99,950

6.0 47,500

2.8 416,600

24.9 309,750

18.5 106,850

6.4 1,117,190

66.8 158,300

9.5

958,890 57.3

Cao Bang 39,580 8.2

12,600 2.6

26,980 5.6

91,240 18.9

81,870 16.9

9,370 2.0

352,300 72.9

6,300 1.3

346,000 71.6

Bac Thai* 26,300 9.2

17,310 6.0

8,990 3.2

158,240 55.2

115,400 40.2

42,840 15.0

101,940 35.6

5,770 2.0

96,170 33.6

Lang Son 39,630 8.1

30,670 6.2

8,960 1.9

61,620 12.6

30670 6.3

30,950 6.3

397,870 81.0

61,340 12.5

336,530 68.5

Quang Ninh - - - 19,940 15.1

19,940 15.1

0 111790 84.8

39,890 30.3

71,900 54.5

Ha Bac* 41,940 14.9

39,370 14.0

2,570 0.9

85,560 30.5

61,870 22.0

32,690 18.5

153,290 54.6

45,000 16.0

108,290 38.6

Grade 1 Grade 2 Grade 3 Grade 4 Limestone Locality S % S % S % S % % Region 0 0 405,000 12.8 1,962,500 61.8 352,500 11.1 14.3 Cao Bang Lang Son Bac Thai* Quang Ninh Ha Bac*

0 0 0 0 0

0 0 0 0 0

117,500

95,000

72,500

32,500

87,500

12.8

11.2

11.2

7.7

25.9

480,000

555,000

487,500

220,000

220,000

52.3

65.3

75.3

52.1

65.2

35,000

80,000

37,500

170,000

30,000

3.8

9.4

5.8

40.2

8.9

30.9

14.1

7.7 - -

Grade 1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 219,770

15.5 87,740

5.3 172,030

10.2 1,132,150

67.7 306,980

18.3 486,390

29.1 279,080

16.7 154,980

9.3 124,100

7.4 Cao Bang 100,920

20.9 18,900

3.9 82,020

17.0 352,210

72.9 81,870

16.9 270,440

56.0 29,690

6.1 0 29,690

6.1 Bac Thai* 42,500

14.8 28,550

10.0 13,950

4.8 212,500

74.2 68,550

23.9 112,470

39.3 31,480

11.0 23,080

8.0 8,400

3.0 Lang Son 63,550

13.0 30,670

6.3 32,880

6.7 357,430

73.1 61,340

12.5 201,730

41.3 68,140

13.9 30,670

6.3 37,470

7.6 Quang Ninh

17,700 13.4

3,990 3

13,710 10.1

100,320 76.0

55,840 42.3

44,480 33.7

13,770 10.4

0 13,770 10.4

Ha Bac* 35,100 12.5

5,630 2.0

29,470 10.5

109,690 39.1

39,380 14.0

70,310 25.1

136,000 36.9

101,230 36

24,770 0.9

Class 1 ( <15o) (in ha/%) Class 2 ( 15-25o) (in ha/%) Class 3 ( 25-35o) (in ha/%) Class 4 ( >35o) (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested

Page 5 of 6

Table 33: Distribution of forest land with different soil depths in the Coastal North Central

Table 34: Distribution of forest land with different soil texture classes in the Coastal North Central Vietnam

Back to contents Next>>

Region 330,530 11.8

59,595 2.1

279,935 9.7

797,940 28.5

393,570 14.1

404,370 14.4

1,275,790 45.5

827,970 29.6

447,820 15.9

395,790 14.1

318,865 11.4

76,925 2.7

Thanh Hoa

86,070 14.5

46,115 7.8

39,955 6.7

250,500 42.2

119,900 20.2

130,600 22.0

254,650 42.9

159,100 26.8

95,550 16.1

2,380 0.4

2,305 0.04

75 0.02

Nghe An 31,260 3.2

1,990 0.2

29,270 3.0

307,780 31.5

154,950 15.8

152,830 15.6

557,820 57.1

353,610 36.2

204,210 20.9

80,110 8.2

59,595 6.1

20,515 2.1

Ha Tinh 25,240 10.9

2,180 0.9

23,060 10.0

71,550 30.9

66,410 28.7

5,140 2.2

126,200 54.5

117,321 50.7

8,880 3.8

8,570 3.7

5,900 2.6

2,630 1.1

Quang Binh

75,950 19.5

7,630 1.2

68,320 17.5

84,410 21.6

38,170 9.8

46,240 11.8

136,710 35.1

116,430 29.9

20,280 5.2

92,410 23.7

89,720 23.0

2,690 0.7

Quang Tri

65,240 23.7

- 65,360 23.7

41,130 14.9

7,430 2.7

33,700 12.2

96,810 35.1

27,840 10.1

68,970 25.0

72,500 26.3

58,690 20.2

16,810 6.1

TT Hue 46,650 14.0

1,680 0.5

44,970 13.5

42,570 12.8

6,710 2.0

35,860 10.8

103,600 31.1

53,670 16.1

49,930 15.0

139,820 42.0

105,655 31.7

34,165 10.3

Classes 1 &2 ( >100cm) (in ha /%) Class 3 (50-100cm) (in ha / %) Class 4 ( < 50cm) ( in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 389,200

13.9 221,395

7.9 167,805

6.0 1,531,600

54.7 932,040

33.3 599,560

21.4 879,200

31.4 446,555

1.6 432,645

15.4 Thanh Hoa 89,260

15.0 88,925

14.9 335 0.1

434,700 73.2

221,350 37.3

213,350 35.9

69,640 11.7

17,145 2.9

52,495 8.8

Nghe An 65,100 6.6

59,600 6.1

5,500 0.5

777,280 79.5

484,720 49.6

292,560 29.9

134,540 13.8

25,825 2.6

108,715 11.1

Ha Tinh 73,540 31.7

52,310 22.6

21,230 9.1

123,150 53.2

106,800 46.1

16,350 7.1

34,870 15.1

32,700 14.1

2,170 1.0

Quang Binh 74,600 19.2

11,450 2.9

63,150 16.2

69,850 17.9

59,170 15.2

10,680 2.7

245,030 62.9

181,330 46.0

63,700 16.3

Quang Tri 73,080 26.5

7,430 2.7

65,650 23.8

96,200 34.9

48,260 17.5

48,000 17.4

106,460 38.6

35,260 12.8

71,200 25.8

TT Hue 13,620 4.1

1,680 0.5

11,940 3.6

30,360 9.1

11,740 3.5

18,620 5.6

288,660 86.8

154,295 46.4

134,365 40.4

Classes 1 &2: Loam (in ha/%)

Class 3: Clay (in ha/%)

Class 4: Sandy soil (in ha/%)

Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-forested

Region 1,436,840 51.3

587,230 21.0

849,610 30.3

1,028,420 36.7

428,860 15.3

599,560 21.4

334,740 12.0

212,530 7.9

122,210 4.1

Thanh Hoa 224,565 38.0

321,590 5.8

190,975 32.2

368,035 62

292,830 49.3

75,205 12.7

- - -

Nghe An 445,390 45.6

188,720 19.3

256,670 26.3

327,620 33.5

244,350 25.0

83,270 8.5

203,910 20.8

137,075 14.0

66,835 6.8

Ha Tinh 84,050 36.3

60,990 26.3

23,360 9.9

147,510 63.7

130,820 56.5

16,350 7.1

- - -

Quang Binh 250,825 64.4

134,980 34.6

119,845 29.7

100,875 25.9

87,800 22,5

10,680 2.7

37,780 9.7

29,170 7.5

8,610 2.2

Quang Tri 151,415 64.4

37,130 13.5

114,285 41.4

59,020 23.0

25,990 8.0

48,000 15.0

65,365 23.7

27,840 0.1

37,525 13.6

TT Hue 279,595 84.0

130,820 39.3

148,775 44.7

25,360 7.6

18,450 5.5

6,910 2.1

27,685 8.3

18,445 5.5

9,240 2.8

Page 6 of 6

Table 32: Distribution of sloping forest land in the Coastal North Central Vietnam

Table 33: Distribution of forest land with different soil depths in the Coastal North Central

Table 34: Distribution of forest land with different soil texture classes in the Coastal North Central Vietnam

Table 35: Distribution of forest land with different soil organic matter contents

in the Coastal Nroth Central Vietnam

Table 36: Distribution of forest land in the Costal Nroth Central Vietnam (or the former 4th Zone)

Class 1 ( <15o) (in ha/%) Class 2 ( 15-25o) (in ha/%) Class 3 ( 25-35o) (in ha/%) Class 4 ( >35o) (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 330,530

11.8 59,595

2.1 279,935

9.7 797,940

28.5 393,570

14.1 404,370

14.4 1,275,790

45.5 827,970

29.6 447,820

15.9 395,790

14.1 318,865

11.4 76,925

2.7 Thanh Hoa 86,070

14.5 46,115

7.8 39,955

6.7 250,500

42.2 119,900

20.2 130,600

22.0 254,650

42.9 159,100

26.8 95,550

16.1 2,380

0.4 2,305 0.04

75 0.02

Nghe An 31,260 3.2

1,990 0.2

29,270 3.0

307,780 31.5

154,950 15.8

152,830 15.6

557,820 57.1

353,610 36.2

204,210 20.9

80,110 8.2

59,595 6.1

20,515 2.1

Ha Tinh 25,240 10.9

2,180 0.9

23,060 10.0

71,550 30.9

66,410 28.7

5,140 2.2

126,200 54.5

117,321 50.7

8,880 3.8

8,570 3.7

5,900 2.6

2,630 1.1

Quang Binh

75,950 19.5

7,630 1.2

68,320 17.5

84,410 21.6

38,170 9.8

46,240 11.8

136,710 35.1

116,430 29.9

20,280 5.2

92,410 23.7

89,720 23.0

2,690 0.7

Quang Tri 65,240 23.7

- 65,360 23.7

41,130 14.9

7,430 2.7

33,700 12.2

96,810 35.1

27,840 10.1

68,970 25.0

72,500 26.3

58,690 20.2

16,810 6.1

TT Hue 46,650 14.0

1,680 0.5

44,970 13.5

42,570 12.8

6,710 2.0

35,860 10.8

103,600 31.1

53,670 16.1

49,930 15.0

139,820 42.0

105,655 31.7

34,165 10.3

Classes 1 &2 ( >100cm) (in ha /%) Class 3 (50-100cm) (in ha / %) Class 4 ( < 50cm) ( in ha/%) Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 389,200

13.9 221,395

7.9 167,805

6.0 1,531,600

54.7 932,040

33.3 599,560

21.4 879,200

31.4 446,555

1.6 432,645

15.4 Thanh Hoa 89,260

15.0 88,925

14.9 335 0.1

434,700 73.2

221,350 37.3

213,350 35.9

69,640 11.7

17,145 2.9

52,495 8.8

Nghe An 65,100 6.6

59,600 6.1

5,500 0.5

777,280 79.5

484,720 49.6

292,560 29.9

134,540 13.8

25,825 2.6

108,715 11.1

Ha Tinh 73,540 31.7

52,310 22.6

21,230 9.1

123,150 53.2

106,800 46.1

16,350 7.1

34,870 15.1

32,700 14.1

2,170 1.0

Quang Binh 74,600 19.2

11,450 2.9

63,150 16.2

69,850 17.9

59,170 15.2

10,680 2.7

245,030 62.9

181,330 46.0

63,700 16.3

Quang Tri 73,080 26.5

7,430 2.7

65,650 23.8

96,200 34.9

48,260 17.5

48,000 17.4

106,460 38.6

35,260 12.8

71,200 25.8

TT Hue 13,620 4.1

1,680 0.5

11,940 3.6

30,360 9.1

11,740 3.5

18,620 5.6

288,660 86.8

154,295 46.4

134,365 40.4

Classes 1 &2: Loam (in ha/%)

Class 3: Clay (in ha/%)

Class 4: Sandy soil (in ha/%)

Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 1,436,840

51.3 587,230

21.0 849,610

30.3 1,028,420

36.7 428,860

15.3 599,560

21.4 334,740

12.0 212,530

7.9 122,210

4.1 Thanh Hoa 224,565

38.0 321,590

5.8 190,975

32.2 368,035

62 292,830

49.3 75,205

12.7 - - -

Nghe An 445,390 45.6

188,720 19.3

256,670 26.3

327,620 33.5

244,350 25.0

83,270 8.5

203,910 20.8

137,075 14.0

66,835 6.8

Ha Tinh 84,050 36.3

60,990 26.3

23,360 9.9

147,510 63.7

130,820 56.5

16,350 7.1

- - -

Quang Binh 250,825 64.4

134,980 34.6

119,845 29.7

100,875 25.9

87,800 22,5

10,680 2.7

37,780 9.7

29,170 7.5

8,610 2.2

Quang Tri 151,415 64.4

37,130 13.5

114,285 41.4

59,020 23.0

25,990 8.0

48,000 15.0

65,365 23.7

27,840 0.1

37,525 13.6

TT Hue 279,595 84.0

130,820 39.3

148,775 44.7

25,360 7.6

18,450 5.5

6,910 2.1

27,685 8.3

18,445 5.5

9,240 2.8

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Localtity S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 254,730

9.1 248,580

8.9 6,150

0.2 867,370

31.0 752,720

26.9 114,650

4.1 1,048,120

37.4 472,170

16.7 575,950

20.7 629,780

22.5 116,530

4.2 513,250

18.3 Thanh Hoa

16,620 2.8

15,060 2.5

1,560 0.3

200,000 33.7

171,710 28.9

28,330 4.8

357,940 60.3

14,650 23.7

217,290 36.6

19,000 3.2

- 19,000 3.2

Nghe An 141,650 14.5

140,990 14.4

660 0.1

236,415 24.2

210,620 21.6

25,795 2.6

368,300 37.7

162,890 16.7

205,410 21.0

230,555 23.6

55,645 5.7

174,910 17.9

Ha Tinh 56,730 24.5

56,290 24.3

440 0.2

107,445 46.4

103,720 44.8

3,725 1.6

40,060 17.3

17,140 7.4

22,920 9.9

27,325 11.8

4,660 2.0

22,665 9.8

Quang Binh

35,550 9.1

32,450 8.3

3,100 0.8

130,475 33.5

129,700 33.3

775 0.2

98,930 25.4

72,620 18.6

26,310 6.8

124,525 32.0

17,180 4.4

107,345 27.6

Quang Tri 2,205 0.8

1,860 0.7

345 0.1

46,680 16.9

31,560 11.4

15,120 5.5

78,600 28.5

35,270 12.8

43,330 15.7

148,315 53.8

22,270 8.1

126,045 45.7

TT Hue 1,975 0.6

1,930 0.5

45 0.1

146,315 44.0

105,410 31.7

40,905 12.3

104,290 31.4

43,600 13.1

60,690 18.3

80,060 24.0

16,775 5.0

63,285 19.0

Grade 1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 3,150

0.11 2,305 0.08

800 0.03

1,093,680 39.1

606,870 21.7

486,810 17.4

1,593,700 56.9

973,760 34.8

619,940 22.1

109,515 3.9

17,065 0.6

92,450 3.3

Page 1 of 5

Table 37: Distribtion of sloping forest land in the Coastal South Central

*Former administrative units

Table 38: Distribution of forest land with different soil depths in the Coastal South Vietnam

*Former administrative units

Table 39: Distribution of forest land with different soil texture classes in the

Coastal South Vietnam

*Former administrative units

Table 40: Distribution of forest land with different soil organic matter contents in the Coastal South Central Vietnam

*Former administrative units

Table 41: Distribution of forest land in the Coastal South Central Vietnam assesses into grades

Thanh Hoa 3,150 0.11

2,305 0.08

800 0.03

200,995 33.8

124,510 20.9

76,440 12.9

290,540 48.9

191,380 32.2

99,160 16.7

99,000 16.7

9,225 1.6

89,775 15.1

Nghe An - - - 532,420 54.5

218,525 22.3

313,895 23.1

444,500 45.5

351,620 36.9

92,880 9.5

- - -

Ha Tinh - - - 143,105 61.8

128,600 55.5

14,505 6.3

88,455 38.2

63,210 27.3

25,245 10.9

- - -

Quang Binh

- - - 115,675 29.7

86,720 22.3

28,955 7.4

269,520 69.2

162,240 41.6

107,280 27.5

4,285 1.1

2,990 0.7

1,295 0.4

Quang Tri - - - 52,710 19.1

1,680 0.6

51,030 18.5

216,860 78.6

84,430 30.6

132,430 48.0

6,230 2.3

4,850 1.7

1,380 0.6

TT Hue - - - 48,815 14.7

46,835 14.1

1,980 0.60

283,825 85.3

120,880 36.3

162,945 49.0

- - -

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 1,095,320

34.7 363,390

11.5 731,930

23.2 366,080

11.6 198,500

6.3 167,580

5.3 98,660

3.1 53,160

1.7 45,500

1.4 1,599,940

50.6 1,074,950

34.0 524,990

10.6 Da Nang 149,330

17.2 9,970 1.1

139,360 16.1

51,430 5.9

14,950 1.7

36,480 4.2

34,840 4.0

18,270 2.1

16,570 1.9

633,820 72.9

448,510 51.6

185,310 21.3

Nghia* Binh

210,690 29.2

2,530 1.2

202,160 29.5

56,940 7.9

5,690 0.8

51,250 7.1

21,350 3.0

8,530 1.2

12,820 1.8

431,360 59.9

201,910 28.0

229,450 31.9

Phu* Khanh

244,110 33.8

31,340 4.3

212,770 29.5

119,000 16.5

47,020 6.5

71,980 10.0

22,890 3.2

11,190 1.5

11,700 1.7

335,660 46.5

253,000 35.1

82,660 11.4

Thuan* Hai

491,190 57.9

313,550 36.9

177,640 20.8

138,710 16.3

130,840 15.4

7,870 0.9

19,580 2.3

15,170 1.8

4,410 0.5

199,100 23.5

171,530 20.2

27,570 3.3

Classes 1 &2 (in ha/%) ( > 100cm)

Class 3 (in ha/%) ( 50-100cm)

Class 4 (in ha/%) ( < 50cm)

Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 1,202,090

38.0 457,300

14.5 744,790

23.5 777,300

24.6 574,090

18.2 203,210

6.4 1,180,610

37.4 688,610

21.8 492,000

15.6 Da Nang 408,160

46.9 207,640

23.9 200,520

23.0 285,380

32.8 192,690

22.2 92,690

10.6 175,880

20.3 91,370 10.9

84,510 9.4

Nghia Binh* 229,200 31.8

48,440 6.7

180,760 25.1

65,440 9.1

22,750 3.2

42,740 5.9

425,650 59,1

173,470 24.0

252,180 35.1

Phu Khanh* 186,140 25.8

20,150 2.8

165,990 23.0

109,850 15.2

49,260 6.8

60,590 8.4

425,670 59.0

273,140 37.8

15,230 21.2

THuan Hai* 378,590 44.6

181,070 21.3

197,520 23.3

316,580 37.3

309,390 36.5

7,190 0.8

153,410 18.1

150,630 17.8

2,780 0.3

Classes 1 &2 (in ha/%) ( > 100cm)

Class 3 (in ha/%) ( 50-100cm)

Class 4 (in ha/%) ( < 50cm)

Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 25,210

8.0 88,570

2.8 163,940

5.2 2,655,750

84.0 1,546,610

48.9 1,109,140

35.1 251,740

8.0 58,820

2.0 1192,920

6.0 Da Nang 107,580

12.4 53,160

6.1 54,690

6.3 721,180

82.9 420,260

48.3 300,920

34.6 40,390

4.7 18,280

2.1 22,110

2.6 Nghia Binh* 48,400

6.6 48,400

6.7 633,500

87.9 221,810

30.8 411,690

57.1 28,440

34 2,850 0.3

35,590 6.1

Phu Khanh* 47,300 6.6

2,240 0.4

45,060 6.2

649,950 90.0

331,350 75.9

318,600 44.1

24,410 3.4

8,960 1.3

15,450 2.1

THuan Hai* 48,960 5.8

33,170 3.9

15,670 1.9

651,120 76.7

573,190 67.5

77,930 9.2

14,850 17.5

28,730 3.4

119,770 14.1

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 8,300

0.3 8,300 0.3

- 207,210 6.6

195,120 6.2

12,090 0.4

619,460 19.6

567,820 18.0

51,640 1.6

2,325,030 73.5

928,760 29.3

1,396,270 44.2

Da Nang 8,300 0.9

8,300 0.9

- 104,530 12.0

94,680 10.9

9,850 1.1

258,830 29.8

220,930 25.4

37,900 4.4

497,760 57.1

167,790 19.3

329,970 27.8

Nghia Binh*

- - - 34,170 4.7

33,410 4.6

760 0.1

112,460 15.6

110,910 15.4

1,550 0.2

573,710 79.7

80,340 11.2

493,370 68.5

Phu Khanh*

- - - 47,300 6.6

46,400 6.4

900 0.2

138,840 19.2

131,200 18.2

7,640 1.0

355,520 74.2

164,950 22.9

370,570 51.3

Thuan Hai*

- - - 21,210 2.5

20,630 2.4

580 0.1

109,330 12.9

104,780 12.3

4,550 0.6

718,040 84.6

515,680 60.8

202,360 23.8

Page 2 of 5

*Former administrative units

Table 42: Distribution of forest sloping land on Tay Nguyen High Plateau

Table 43: Distribution of forest land with different soil organic matter contents on Tay Nguyen High Plateau

Table 44: Distribution of forest land with different soil depths on Tay Nguyen High Plateau

Table 45: Distribution of forest land with different soil texture classes on Tay Nguyen High Plateau

Table 46: Distribution of forest land on Tay Nguyen High Plateau assessed into grades

Grade1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region - - - 991,750

31.4 319,490

10.1 672,260

21.3 822,590

26.0 642,860

20.3 179,730

5.7 134,566

42.6 737,370

23.3 608,290

19.3 Da Nang - - - 230,630

26.5 92,020

10.7 137,610

15.8 264,940

30.5 204,840

23.6 60,100

6.9 373,850

43.0 193,840

22.3 180,010

20.7 Nghia Binh*

- - - 199,300 27.7

17,060 2.4

182,240 25.3

225,700 31.4

158,260 21.9

67,440 9.5

295,340 42.9

49,340 6.8

246,000 36.1

Phu Khanh*

- - - 204,440 28.3

24,630 3.4

179,810 24.9

214,120 29.6

166,820 23.1

47,300 6.5

303,100 43.1

151,100 20.9

152,000 21.2

Thuan Hai*

- - - 357,380 42.1

184,780 21.8

172,600 20.3

117,830 13.9

112,940 13.3

4,890 0.6

373,370 44.0

343,090 40.4

30,280 3.6

Class 1 (15o) (in ha/%) Class 2 (15-25o) (in ha/%) Class 3 (25-35o) (in ha/%)

Class 4 (>35o) (in ha/%)

Locality S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

Region 698,920 15.74

437,170 9.85

255,640 5.89

525,450 11.83

351,500 7.92

173,950 3.91

1,983,520 44,69

1,480,190 33.35

503,330 11.34

1,266,140 28.53

988,140 22.26

278,274 6.27

Gia Lai 201,280 15.7

101,260 7.90

100,020 7.8

166,440 13.0

101,250 7.9

65,190 5.1

650,290 50.75

375,240 29.28

275,050 21.47

263,220 20.54

226,350 17.66

36,870 2.88

Kontum 6,110 0.67

110,000 12.12

60,210 6.63

49,790 5.49

336,100 37.03

240,840 26.53

95,260 10.50

455,270 50.17

339,790 37.44

115,480 12.73

Daklak 402,650 27.85

260,660 18.03

141,990 9.82

160,200 11.08

139,870 9.67

20,330 1.41

572,970 39.63

521,310 36.06

051,660 3.57

309,780 21.43

279,690 19.34

30,090 2.09

Lam Dong 88,880 11.06

75,250 9.36

13,630 1.7

88,810 11.05

50,170 6.24

38,640 4.81

424,160 52.77

342,800 42.65

81,368 10.12

238,144 29.63

142,310 17.7

95,834 11.93

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) LOcality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 1,331,160

30 1,175,830

26.5 155,330

3.5 1,601,640

36.08 1,417,190

31.93 184,450

4.15 1,158,530

26.1 638,460 14.38

520,070 11.72

346,680 7.83

38,320 0.89

308,360 6.94

Gia Lai 277,880 21.68

257,380 20.08

20,500 1,6

396,000 30.9

339,500 26.49

56,500 4.41

474,720 37.05

195,300 15.24

279,420 21.81

132,630 10.37

11,920 0.95

120,710 9.42

Kontum 354,440 39.05

352,660 38.86

1,780 0.19

314,720 34.68

236,540 26.06

78,180 8.61

238,320 26.26

51,640 5.69

186,680 20.57

Daklak 337,930

23.37 314,960 21.78

22,970 1.59

593,250 41.03

590,320 40.83

2,930 0.2

300,380 20.77

282,650 19.55

17,730 1.22

214,050 14.8

26,400 1.85

187,650 13.0

Lam Dong

360,910 44.90

250,830 31.20

110,080 13.69

297,670 37.03

250,830 31.2

46,840 5.82

145,110 18.05

108,870 13.54

36,240 4.51

Classes1&2 (in ha/%) ( > 100cm)

Class 3 (in ha/%) (50-100cm)

Class 4 (in ha/%) (<50cm)

Locality S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

Region 2,094,644 47.19

1,732,490 39.03

362,154 8.16

437,100 9.84

246,210 5.54

190,890 4.3

1,906,260 42.95

1,268,360 28.57

637,900 14.37

Gia Lai 220,630 17.22

214,420 16.73

06,210 0.48

158,700 12.38

101,260 7.9

57,440 4.48

901,900 70.39

448,420 35.0

453,480 35.39

Kontum 516,350 56.90

326,860 36.01

189,520 20.88

64,170 7.07

4,300 0.47

59,870 6.59

226,930 36.02

309,740 34.13

17,190 1.89

Daklak 978,114 67.66

902,760 62.44

75,354 5.21

87,730 6.06

44,500 3.07

43,230 2.99

379,760 26.27

254,270 17.58

125,490 8.68

Lam Dong

379,520 47.22

288,450 35.89

91,070 11.33

126,500 15.73

96,150 11.96

30,350 3.77

297,670 37.03

255,930 31.84

41,740 5.19

Class 1&2: Loam (in ha/%)

Class 3: Clay (in ha/%)

Class 4: Sandy soil (in ha/%)

Locality S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

Region 613,660 13.82

211,660 4.77

401,998 9.05

2,824,920 63.65

2,178,190 49.08

646,730 14.57

999,438 22.52

867,158 19.54

132,280 2.98

Gia Lai 282,560 22.05

113,670 8.87

168,890 13.18

685,120 53.47

494,370 38.58

194,750 14.89

313,550 24.47

196,060 15.3

117,490 9.17

Kontum 61,110 6.73

34,410 3.79

26,700 2.94

836,260 92.15

597,800 65.87

238,460 26.27

10,110 1.11

8,630 0.95

1,480 0.16

Daklak 269,980 18.67

63,580 4.40

206,400 14.27

572,550 39.6

546,740 37.82

25,810 1.78

603,070 41.71

591,210 40.90

11,860 0.81

Lam Dong

730,990 90.95

539,280 67.10

191,710 23.85

72,700 09.05

71,250 8.86

1,450 0.19

Page 3 of 5

Table 47: Distribution of sloping forest land in the East South Vietnam

Table 48: Distribution of forest land with different soil depths in the East South Vietnam

Table 49: Distribution of forest land with diferent soil texture classes in the East South Vietnam

Table 50: Distribution of forest land with different soil organic matter contents in the East South Vietnam

Table 51: Distribution of forest land in the East South Vietnam assessed into grades

Grade 1 (in ha/%) Grade 2 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 123,050

2.77 53,440

1.2 69,610

1.56 1,739,300

39.19 1,468,920

33.1 270,380

6.92 2,552,400

57.51 1,734,640

39.08 817,760 18.42

23,650 0.53

Gia Lai 81,280

6.34 23,830 1.86

57,450 4.48

332,880 25.98

256,120 20.0

76,760 6.0

847,690 66.16

524,150 40.91

323,540 25.25

19,830 1.55

Kontum 357,440

39.98 266,650

29.38 90,790 10.0

549,990 60.60

374,190 41.23

175,800 19.37

Daklak 34,330

2.37 25,430 1.76

9,800 0.61

747,590 51.71

712,040 49.25

35,550 2.45

659,860 45.64

464,060 32.10

195,800 13.54

3,820 0.26

Lam Dong

7,440 0.98

4,180 0.52

3,250 0.4

301,390 37.5

234,110 29.13

67,250 8.37

494,860 60.32

372,240 46.31

122,620 15.25

Class 1: < 15o (in ha/%) Class 2 :15-25o (in ha/%)

Class 3 (in ha/%) Class 4 (in ha/%)

Locality S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

S Forested Non-forested

Region 270,990 48.92

227,290 41.02

43,700 7.9

132,840 23.98

120,180 21.7

12,660 2.28

48,900 8.83

35,280 6.37

13,620 2.46

101,270 18.28

71,250 12.86

30,020 5.42

Song Be 80,370 25,8

75,990 24.38

4,380

102,210 32.8

99,740 32.0

2,470 31,800 10.2

23,750 7.62

8,050 97,240 37.2

71,250 22.86

25,990 8.34

Tay Ninh 62,520 91.65

43,030 63.08

19,490 28.57

5,690 8.34

- 5,690 8.34

- - - - - -

Dong Nai 76,420 66.91

71,470 62.57

4,950 4.34

20,300 17.77

16,140 14.13

4,160 3.64

14,680 12.85

11,530 10.09

3,150 2.76

2,180 2.46

- 2,810 2.46

Vung Tau 37,810 82.0

30,120 65.35

7,690 16.68

4,640 10.06

4,300 9.33

340 0.73

2,420 5.25

- 2,420 5.25

1,220 2.64

- 1,220 2.64

HCM city 13,870 100

6,680 48.16

7,190 51.84

- - - - - - - - -

Classes 1 &2 (in ha/%) ( > 100cm)

Class 3 (in ha/%) ( 50-100cm)

Class 4 (in ha/%) ( < 50cm)

Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 344,470

62.17 300,640

54.26 43,830 7.91

90,040 16.97

84,080 15.17

9,960 1.80

115,490 20.84

69,280 12.5

46,210 8.34

Song Be 213,050 68.37

208,980 67.08

4,070 1.31

50,880 16.32

47,500 15.24

3,380 1.08

47,690 15.30

14,250 4.57

33,440 10.73

Tay Ninh 56,840 88.33

43,030 63.08

13,810 25.25

5,680 8.32

- 5,680 8.32

5,690 8.33

- 5,690 8.33

Dong Nai 29,960 26.33

16,140 14.13

13,820 12.10

33,060 28.95

32,280 28.26

0,780 0.69

51,190 44.82

50,720 44.41

470 0.41

Vung Tau 30,750 66.71

25,810 56.0

4,940 10.71

4,420 9.59

4,300 9.33

120 0.26

10,920 23.7

4,310 9.35

6,610 14.35

HCM city 13,870 100

6,680 48.17

7,190 51.83

- - - - - -

Classes 1 &2: Loam (in ha/%)

Class 3: Clay (in ha/%)

Class 4 (in ha/%)

Locality S Forested Non-forested S Forested Non-forested S Forested Non-forested Region 129,890

23.44 109,270

19.72 20,620 3.72

384,750 69.45

311,070 56.15

73,680 13.3

39,360 7.10

33,660 6.07

5700 1.03

Song Be 6,360 2.04

- 6,360 2.04

302,080 96.94

270,730 86.88

31,350 18.12

3,180 1,02

- 3180 1.02

Tay Ninh 49,790 72.99

43,030 63.03

6,760 9.91

18,420 27.0

- 18,120 27.0

- - -

Dong Nai 58,680 51.38

57,640 50.47

1,040 0.91

33,060 28.94

20,750 18.17

12,310 10.77

22,470 19.67

20,750 18.17

1720 1.5

Vung tau 14,550 31.57

8,600 18.66

5,950 12.91

17,830 38.67

12,910 28.01

04,920 10.66

13,710 29.75

12,910 28.01

800 1.74

HCM city 510 3.67

- 510 3.67

13,360 96.32

6,680 48.16

6,680 48.16

- - -

Class 1 (in ha/%) Class 2 (in ha/%) Class 3 (in ha/%) Class 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 13,940

2.51 13,940

2.51 282,610 51.01

258,690 46.69

23,920 4.31

219,120 39.55

162,790 29.38

56,330 10.16

38,330 6.92

23,520 4.24

14,810 2.67

Song Be - - 186,730 59.92

170,980 54.87

15,750 5.05

122,170 39.2

90,750 29.12

31,420 10.08

2,720 0.87

- 2,720 0.87

Tay Ninh 11,370 16.67

11,370 16.67

45,470 66.66

43,030 63.08

2,440 3.58

11,370 16.67

- 11,370 16.67

- - -

Dong Nai - - 28,550 24.99

26,860 23.51

1,690 1.48

56,150 49.16

53,060 46.45

3,090 2.52

29,510 25.83

19,220 16.82

10,290 9.01

Vung tau - - 20,750 45.02

17,210 37.33

3,540 7.69

19,240 41.47

12,910 28.01

6,330 13.73

6,100 13.23

4,300 9.32

1,800 3.91

HCM city 2,570 18.53

2,570 18.53

1,110 8.0

610 4.40

500 3.60

10,190 73.46

6,070 43.76

4,120 29.70

- - -

Page 4 of 5

Back to contents Next>>

Grade 1 (in ha/%) Grade 1 (in ha/%) Grade 3 (in ha/%) Grade 4 (in ha/%) Locality S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested S Forested Non-

forested Region 56,840

10.25 43,030 7.68

13,810 2.49

318,170 57.42

286,140 51.64

032,030 5.78

176,830 31.9

124,830 22.53

52,000 9.38

2,150 0.39

2,150 0.39

Song Be - - - 197,150 63.26

180,480 57.91

16,670 5.35

114,470 36.73

90,250 28.96

24,220 7.77

-

Tay Ninh 56,840 33.33

43,030 63.08

13,810 20.25

5,680 8.32

- 5,680 8.32

5,680 8.32

- 5680 8.32

-

Dong Nai - 71,150 62.30

68,860 60.30

2,290 2.0

42,130 36.89

30,280 26.51

11,850 1.038

930 0.81

930 0.81

Vung Tau - 30,320 65.78

30,120 65.35

0,200 0.43

14,550 31.56

4,300 9.32

10,250 22.24

1,220 2.64

1,220 2.64

HCM city - 13,870 100

6,680 48.17

7,190 51.83

- - - -

Page 5 of 5

Chapter 3

Assessing the Potential Productivity of Coastal Sandy Soils for Use in Forestry. Following the Himalayan orogenesis at the end of the quaternary era, the continent shelf has been raised to create conditions for the formation of flats along the coasts of Vietnam (J. Fromaget. 1927; VM Fridland, 1964; E. Saurin, 1967); then comes the formation of sandy areas due to the combined action of sea waves and winds, in which the following sandy soils can be found: Red sandy soil (of pleistocene period: 150,000-600,000 years of age). It can be found on moving and/or fixed sand dunes at elevations of 30-100 m asl (more rarely at 200 m asl), mainly in the South of Central Vietnam, at Binh Thuan and Ninh Thuan. White sandy soil (of Holocene period: 5,000-10,000 years of age). It is found on flats and on fixed or moving sand dunes at lower elevations of about 5-50 asl, at the provinces of Quang Binh, Quang Tri, Thua Thien Hue, Quang Nam and Da Nang in Central Vietnam. Yellow sandy soil (of more recent formation) It is found on low and flat areas, on fixed moving sand dunes at elevations of 2-100 m asl at a younger stage of development along the coasts of Vietnam, from North to South. The total area of sand soils in Vietnam extends over 502,045 hectares (on 1.4% of total land mass-Agriculture Planning and Engineering Institute-1980), in almost all provinces bordering the coasts from Quang Ninh to the Mekong Delta (on a belt of 50 m-10 km along the coats). - The largest sandy soil area is found along the costs of the South of Central Vietnam, extending over 264,981 ha; - The next largest one is found in the former 4th zone over 150,582 ha; Then come smaller areas in: -The Mekong Delta, over 49,717 ha; - The East South Vietnam. Over 22,671 ha; - The Midland and mountain area 8,972 ha; of North Vietnam, over - And the Red River delta, over 4,709 ha. (Agriculture Planning and Engineering Institute, 1980) This is to say that sandy soils and sand dunes in this country occur mainly along the coasts of Central Vietnam, from

latitude 11oN to latitude 170 N and from longitude 108o E to longitude 109o E, where the local climate conditions can be described as follows: Air temperature: - Mean annual temperature: 25o-27oC

- Mean temperature of the hottest month: 27,8oC

- Mean temperature of the coldest month: >20oC

- Minimum temperature: > 12oC

- Maximum temperature: 38oC

-Total annual temperature, ranging: 9,000oC-9,500oC. Atmospheric precipitation: highly variable within regions, with - Mean annual precipitation of 550 mm (found at Tuy Phong, in Binh Thuan province) - Mean annual precipitation of 2,600 mm (found in Thua Thien Hue, Quang Nam and Da Nang provinces) Relative humidity: Mean value of 78% found in Binh Thuan and Ninh Thuan; and of 85% found in wetter areas (Thua Thien Hue, Quang Nam, Da Nang provinces). The whole region under study can be characterized by three different bio-climatic zones of: · Wet tropical climate affected by a cold winter;

Page 1 of 16

· Wet tropical climate (extending over a larger area); and semi-arid tropical (or semi- arid for short) climate (covering smaller areas in Binh Thuan and Ninh Thuan, where there are only 30-50 rainy days per year, with annual precipitation of 550-700 mm, 8-9 dry months of which 4 months (from December to March) are of no rains.

On the contrary, in the wet tropical zone, annual precipitation is much higher and better distributed during the year. However, there are areas in which very heavy rains of 300-400 mm a day occur, causing mass sandy soil erosion. 3.1. Classification of Coastal Sand Dunes and Sandy Soils. * In his study, sand dunes and their sandy soils were the sites of many studies to produce soil maps scaled at 1/1,000,000 in the South of Viet nam, (from latitude 170 southwards), F.R. Moormenn (1962-1962) divided the coastal sandy soil ( Regosols) into two sub-types: a/ Yellow sandy soils (80% of the area of which being then unused) b/ Red sandy soil (most the area of which being then unused) *In 1978, following intensive land surveys in the Mekong Delta, and the South of Central Viet nam, the Agriculture Planning and Engineering Institute classified sandy soils along the coasts of the South of Vietnam into three sub-types of: 1/ Dunes of yellow and white sand ( moving and/or fixed); 2/ Halomorphic sandy soil; and 3/ Cultivated sandy soil. Then, coasted sandy soils in Vietnam were systematically studied by Phan Lien in 1981. For the first time, their main characteristics and properties in particular their relationships with ground water were described. The author classified coastal sandy soil into six sub-types. 1.1 / Sea-shore sand;

1.2 / Coastal sand on dunes (moving and fixed);

1.3 / Typical coastal sandy soil;

1.4 / Wet coastal sandy soil;

1.5 / Coastal alluvial sandy soil; and

1.6 / Coastal sea-shell sandy soil.

The first two sub-types are said to be suitable for forest tree cropping. Other three sub-types (4, 5, 6) can be used for farm cropping, with the subtype no.3 supporting both farm crops and tree crops, depending much on the supply of water from ground water table.

* In a field paper “Present Situation of and Tendencies for Land Used in the Socialist Republic of Viet nam” published by the Cetral Land Management Office in 1982, the following classification of coastal sandy soils was presented, based on the results of land surveys made by the Agriculture Planning and Engineering Institute in 1980. The total area of coastal sand dunes and sandy soil of 502,045 ha was divided into: (1) Dunes of yellow and white sand covering: 151,126 ha

(2) Dunes of red sand: 77,017 ha (both of moving or fixed sand dunes. Mainly found

in the South of Central Vietnam).

(3)Coastal andy soil: 233,754 ha

(4) Cultivated sandy soil (found in the Mekong Delta): 39,603 ha (5) Coral sandy soil (found at the former 4th zone and along the coasts of South Central Vietnam): 545 ha

Page 2 of 16

The first two sub-types (1 and 2) can be used for forestry development, and the last two ones (subtypes 4 and 5) are suitable to farm crops, whereas the subtype No. 3, depending its location next to seashore or far way from it, and its uptake of groundwater (during the year) can be used for either agriculture or forestry development, resulting in a mosaic of complex farming systems in the area where the subtype prevails. On the other hand, the Vietnamese Soil Scientists Sociation in 1996, based on the FAO-UNESCO soil mapping system, reshaped the classification of coastal sandy soils in Vietnam into soil groups and units, resulting into five soil units as shown below:

1/ Yellow and white sandy soil on dunes (Luvic Arenosols covering : 222,043 ha. The soil unit covers an outer belt, next to the see-shore, in which sand particles are mixed with alluvia from rivers flowing in neighbouring deltas, and which is extending from Nghe Tinh (1) and going southwards to the provinces of Quang Binh, Quang Tri, Thua Thien Hue, Quang Nam, Da Nang, then down to Binh Thuan and Ninh Thuan, with sand dunes sometimes reaching 200-300 m high, and some of them being moving whereas others being already fixed. 2/ Red sandy soil on dunes (Rhodic Arenosols) covering 76,886 ha Mainly found along the coasts of Binh Thuan province on fixed sand dunes, thus creating a belt of sand dunes of 200m asl. The soil contains some clay and silt particles. The amount of which is found higher than the same in yellow and white sandy soil (with the amount of silt and clay of particle size below 0,01 mm amounting to over 10%). 3/ Coastal sandy soil (Halic Arenosols) covering: 234,505 ha Coastal sandy soils are found on flats, along the coasts from Thanh Hoa to Binh Thuan on a number of belts of different width. Sand beaches or dunes of this kind are greyish white in color. Coaste sand particles are found in layers on beaches, while sand dunes as they are formed by prevailing sea winds are of fine sand and have no clear layers. In some areas of Dien Chau, Quynh Luu..., one can find sea-shell being mixed with coastal sandy soils, thus making them basic or neutral in their reaction. 4/ Immature sandy soil (Cambic Arenosols) 5/ Gley-sandy soil (Gleyic Arenosols) The last two soil units did not receive due attention of soil scientists, and there are no indications of area distribution and properties because of their small area, their irregular and patchy distribution in the coastal provinces of Central Vietnam. ----------- (1) Old name for the provenancevinces of Nghe An and Ha Tinh when they were in only one administrative provenancevincial unit

Table 52-Classification of coastal sandy soils and sand dunes in Vietnam for use in forestry.

Sources: - General Direction of Forestry (1968) - Agriculture Planning and enigeering Institute (1980)

Soil type. Soil Subtype Soil conditions

Major soil groups Soil units (by FAO-UNESCO)

Area (ha)

1-Coastal sandy soil 1.1. Foreshore sandy soil 1.2. Yellow and white sandy soil on dunes 1.2.1.Moving 1.2.2.Fixed 1.3. Red sandy soil on dunes 1.3.1.Moving 1.3.2.Fixed 1.4. Coastal sandy soil. 1.4.1.Good water drainage 1.4.2.Impeded water drainage 1.5. Gley-coastal sandy soil (at near

surface layer) 1.6. Immature coastal sandy 1.7. Coastal soil alluvial sandy soil 1.8. Coastal sea-shell and coral sandy soil 1.9. Cultivated sandy soil

1. Arenosols 1.1. Luvic Arenosols 1.2. Rhodic Arenosols 1.3. Halic Arenosols 1.4. Gleyic Arenosols 1.5. Cambic Arenosols

502,405

151,126

77,017

233,754

545

39,603

Page 3 of 16

- Central Land Management Office (1980) - Forest Land of Vietnam-Forest Science Institute of Vietnam(1996)

- Vietnamese soil scientists Association (1996) 3.2/ Main characteristics of coastal sandy soils in Viet nam. 3.2.1. Yellow and white sandy soil on dunes, covering 151, 126 hectares. Foreshore sandy soil. The sub-type is found on foreshore, next to the sea water line, mainly in flats or on undulating sand dunes in narrow belts about 50-500 m wide. - The groundwater table there is next to soil surface (at a depth of 50-100m) - Soil moisture is rated as moderate; - No waterlogging occurs there in the rainy season; Compared with other sandy soil units/ subtypes it is rated as of fair productivity with a low rate of nutrient leaching (as occurred on immature soils) The soil vegetaiton cover consists mainly of Ipomea biloba (vernacular Rau muong bien) and Spinifex littorcus (vernacular Co long chong) growing in patches. The most important characteristic found on moving sand dune is: the soil there has a low percentage of clay particles but a very high percentage (up to 95-98%) of loose medium and fine sand, which can be easily blown away by sea winds. Along the coasts of central Vietnam, there prevail three types of winds, the North Easterly, the South Easterly and the dry and hot South Westerly; all of them blow at velocity of above 5-11m/sec. The winds blow the sand up so to create sand dunes about 50-100 m high (sometimes 200m high) and the moving sand dunes, under the impacts of winds blowing from the East Sea to the mainland, can threaten villages, pagodas, gardens, houses and access roads in the neibourhood. The moving sand grains can hit tree and plant leaves, young buds of farming crops, and even destroy these crops by uprooting and/or completely covering up both farm and young tree crops; as a result on moving sand dunes, there is no natural vegetation cover. - In a profile dug in on moving sand dunes, there are no clear distinctions of horizons, with its surface layer being

very dry, reaching its permanent wilting point, and soil moisture going to increase only gradually with depths. - The groundwater table is found at very deep layers, because of high soil permeability. - The humus content is very poor (only 0.01-0.06%) as well the amount of mineral nutrients, and the soil pH,

nearly neutrial - Bare sandy soils there can have a very high temperature at their surface (of above 60 oC) as they are exposed to

direct surveys. - The evaporation process from soil is also very high amounting to more than 1,300 mm per year; and - The rate of sand dune moving inland is estimated at 1-2 m annually. Sand dunes fixed by natural vegetation Sand dunes fixed by natural vegetation are noticed at an inner belt, next to inland sandy soils. Natural vegetation forming a protective cover there often includes Fimbystylis sphathaceae (vernacular Co quan do), Fimbystylis sericeae (vernacular Co quan xanh) and other shrub and grass species such as Eugenia spp (vernacular Tram), Desmodium ovalium (vernacular Me dat), Nepenthes annamensis (vernacular Cay nap am), Vitis pentagona (vernacular Cay gio)... Soil analyses show well the effects of the protective natural vegetation cover, it has increased the contents of soil organic matter at the soil surface layer, which are rated as somewhat higher than those found on moving sand dunes, but which are, as a rule, quite poor. The color of sand along the profile experiencing changes shows well the differentiation of soil and the leaching of nutrients, in particular in areas of high precipitation (of above 2,000 mm per annum). 3.2.2/ Red sandy soils on dunes, covering 77,017 hectares. The soil type occurs on a relatively large area, mainly in the province of Binh Thuan, where the climate is semi-arid, with very low annual precipitation ranging from 550 mm/annum to 750 mm/annum, and 8-9 dry months (from December to April). The soil is very dry (from 0 cm to 100 cm) with a moisture of 0.6% to 0.9%; only at a depth of 100cm, does the soil begin to get wetter and wetter, but within the range 1%-1.5% only. From May to August, there are some light showers in the province, then at soil depth of 0-50 cm, there is some

Page 4 of 16

moisture ranging from 1.1% to 2.2%; and at a depth of 150-200cm, there is, sometime, a moisture of 7-8%. Out of 32 observations to record soil moisture during a year, there are: · 24 observations (=75%), in which moisture of 0.6-3% is recorded.

· 5 observations (=16%), in which moisture of 3-5% is noticed; and only

· 3 observations (=9%), in which better moisture of 5-8.5% can be recorded. Moisture in red sandy soils, as in many other sandy soils, is found to get increased only very slowly at soils depths, which, under the conditions of Binh Thuan, is only noticeable at soil depths of 100-150cm from the soil surface so to nurture the cultivation of Casuarinas in that province. The same does not happen in the South of Quang Binh province, where annual precipitation is of the order of 2,000-2,400 mm, and of evener distribution during the year. Conditions in Binh Thuan are much drier, whereas in the South of Quang Binh, even in the dry season, sandy soil moisture is much higher (Lam Cong Dinh,1990). Red sandy soils on dune are dry, loose, and subjected to the influence of strong winds, therefore in Ninh Thuan sandhills are moving inland much faster than elsewhere. There are there sandhills of 100-150m (and even 200m) high, with their pointed crest sloping abruptly at beside, and having such a loose sand so to cover the feet up to 50cm high when walking on. However, the sandy soil there is reported to be older than many others; it has a higher percentage of silt and clay (of particle size below 0.01mm) amounting to 6-10% and having higher cohesion so to limit its saltation and its inland movement. On the other hand, the soil has a relatively higher content of organic matter and other nutrients (NPK and exchangeable bases) as compared with the yellow and white sandy soils, thus providing conditions for natural vegetation, in particular drought resistant and thorny grasses and plants, to colonilize the sites, and the for these red sand dunes to get better stubilized than dunes with yellow and white sandy soils. (3bang ngang) 3.2.3. Coastal sandy soil (Halic Arenosols), covering 233,754 hectares. It is found on flat areas, and extending from Thanh Hoa to Binh Thuan, with a ground water table next to the soil surface, thus causing poor water drainage and waterlogging to occur in the rainy season and leading to the formation of gley-coastal sandy soil (or Gleyic Arenosols). Besides, along the coasts of Quang Tri , Quang Nam, Da Nang , there is another coastal sandy soil type with a layer of accumulated organic detritus next to the water table (Do Dinh Sam 1987; Do Dinh Sam, Ngo Que 1995) and about 60-100 cm from the soil surface, which is named by local people as a “bad smell” sandy soil. Subtypes of coastal sandy soils, of poor water drainage and gley formation (or containing a layer of organic detritus next to the soil surface) can have their limiting effects on the growth of tree crop such as casuarinas, acacias and eucalypts. However, these coastal sandy soils have been used for ages for agriculture farming, using agroforestry practises and “bed raising” methods so to create a checkered cropping pattern, in which casuarinas are planted in belts for the protection of farm crops grown on raised beds. On other coastal sandy soils, those known as alluvial sandy soils or see-shell sandy soils, farmers also grow casuarinas for farm crop protection and the production of sweet potatoes, ground nut, beans... is found to be much improved as noticed at the district of Dien Chau in Nghe An. However, due to limitations by water drainage poor soil productivity, and not the least the beating of moving sand grains, a lot of coastal sandy soils still remain under fallow, being occupied only by a natural vegetation cover of Seirpus junciformis (vernacular Co ruoi), Eragrotis spp (vernacular Co duoi phung), Ischaemum aristatum (vernacular Co la), Cymbopogon caesina (vernacular Co thom... . The main properties of coastal sandy soils are: they have a very high percentage of loose sand (up to 95-98%) subjected

to the saltation process by see winds, quite low contents of humus, total N and P2O5 and K2O, and sometimes low pH

values (with pHKCl ranging from 4.7 to 6.0) in particular on soils under farming. In some areas, due to the use of

phosphates for agricultural farming, there is higher content of available P2O5.

Other properties that can be observed in some areas covered by coastal sandy soils are:

- Their very low water-holding capacity, their high soil temperature ( particular in open areas where their surface

soil temperature in may reach up to 64oC). - Their high evaporation reaching up to 1,300 mm per year; and their ground water sometimes going deep into the

soil especially in the dry season, causing shortage of water supply for farming and even for domestic use by local farmers living in the areas.

- Their soil moisture, usually very low, can go down to below 1%, and reaching the permanent wilting point;

Page 5 of 16

therefore regular and frequent watering of crops on coastal sandy soil becomes an accepted practice, in particular during the long dry season prevailing in these areas.

Dealing with the “bio-activity” of coastal sandy soils, Dr. Phan Lieu (1981) points to the fact that: in spite of being very poor in terms of organic matter content, the “bio-activity” of this type of sandy soil remains high. However, in summer

and on open areas the soil temperature there can be very high (reaching over 640C), which may limit the bio-activity of that soil. Therefore, to secure that bio-process, it is necessary to create a vegetation cover to protect the soil surface from reaching on excessively high temperature in summer during day-time and/on a low temperature during the night in winter in particular in some Northern provinces. 3.3. Assessment of the protential productivity of the coastal sandy soils for use in Vietnam, and the results obtained. 3.3.1. Methodology used. 3.3.1.1. Identification of criteria/ standards For an assessment of the potential productivity of coastal sandy soils for/in use in forestry, we have to consider a number of factors and properties related to both land and soils, among these the land morphology, the rate of sand dune moving inland, water drainage..., in particular all factors/properties having strong impacts on soil formation, land development and yields of tree and farm crops, which are commonly used for assessment in both agriculture and forestry. In forestry, we must pay much attention to factors that may help us define well the technical approachs for tree crop farming and also for environmental conservation, in particular for preventing moving sand grains from ravaging agricultural crops, and for soil improvement. For that purpose, we have selected casuarina (Casuarina equisetifolia) formerly introduced from Australia. The species is said to have been grown in Vietnam since 1898. It is used as a reference tree crop to assess the potential productivity of coastal sandy soils for use in forestry. In 1915, casuarinas were first planted along the coastal areas of Nghe An. In 1934-1938, they were planted on coastal sandy soils and sand dunes of Quang Binh province (Lam Cong Dinh, 1963). Being cultivated for more than a century in Vietnam, casuarina proves to be suitable to Vietnamese conditions and helpful in the struggle against moving sand dunes along the coast from North to South. As of 1945, the sandy area under Casuarina amounted to 80,000 (Midgley at al). When taking into account all planted areas established either in full plantations or in patches as dispersed trees in all homestead areas, around ricefields, and along roadsides-the whole area under casuarina in 1996 may reach 120,000 hectares (Ha Chu Chu and Le Dinh Kha- Forest Science Institute of Vietnam-1996) Casuarina (Casuarina equisetfolia Forest) when grown in Vietnam shows well the following characteristics. It is an evergreen timber species of medium and high size, about 15-20 m high, and 20-40cm thick at breast height when mature. It is a light-demanding species and can be grown from seeds. Under Vietnamese conditions, it performs very well, it is growing very fast and can produce Frankia symbiotic nodules in its root system for nitrogen fixation from the atmosphere, though not being a leguminous species. However, casuarina can not grow well on clayed soils. Casuarina can be grown on coastal sandy soils in Vietnam for sand dune fixation, stabilization of moving sand-hills for agricultural crop protection and also for fuelwood supply to local farmers in the coastal areas where firewood is scarce. Casuarina timber is brownish in color and soft in its texture, with annual growth rings showing out clearly. The wood density is of the order of 0.978. Insects and termites can easily eat and destroy the wood, which can be used as mine props, house building materials, pulpwood... but most appropriately as fuelwood as it can burn easily even when fresh cut. Casuarina bark contains high amount of tennin, which can be used to dye fishing nets. Farmers can also use casuarina bark and leaves to make compost to help them grow farm crops on sandy soils. In Vietnam, casuarina proves to get well adapted to a wide range of local climates, from a quasi-subtropical climate

with a cold winter and with a mean annual temperature of 21.50C and a high annual precipitation of 2,500 mm evenly

distributed round the year (for instance at Tien Yen, at 210570 N latitude), to a typical tropical climate with no cold

season, and with a mean annual temperature of 260C and a relatively low precipitation around 1,000 mm/annum occurring after a pronounced dry season. However, casuarina seems to perform best in areas of low latude, i.e. in areas where a wet tropical climate prevails.

Table 59. Growth of casuarinas on foreshore sandy soils at latitudes of 11057’N-21057’N.

(Hoang Xuan Ty-1996)

Locality Latitude Color of coastal Age (years) Annual growth

Page 6 of 16

Table 60. Growth of casuarinas on Coastal sandy soils of Central Vietnam (Do Dinh Sam and Ngo Que. Forest Science Institute of Vietnam-1995)

Table 61- Growth rate of casuarinas on coastal sandy soils of Vietnam.

N sandy soil In Height (m) In Diameter (cm)

Tien Yen 21057’ Yellow 4-6 1.30 1.20 Hon Gai 21020’ Yellow 5-6 1.32 1.23

Thanh Hoa 20057’ Yellow 5-6 1.44 1.25 Quynh Luu 19008’ Yellow 4-5 1.54 1.46 Dong Hoi 17028’ White 4-6 1.53 1.44 Dong Ha 16015’ White 4-5 1.47 1.44 Da Nang 15046’ White 5-6 1.64 1.45

Quy Nhon 13046’ Yellow 6 1.60 1.56 Cam Ranh 11057’ White 5 1.53 1.50

Locality Age (years) Growth Provenanceperties of soils DD (cm/year) DH (m/year) Soil culture pH (KLC) Humus (%)

Ly Hoa (Quang Binh)

12 0.62 0.46 Loose sand 5.35 0.39

Duy Xuyen-Thang Binh

(Quang Nam)

6-8 0.72-1.03 (0.87)

0.72-1.25 (0.98)

-do- 5.80 0.25-0.53

Duc Pho (Quang Ngai)

17 0.95 1.02 -do- 5.40 0.35

Nhon Hoi (Binh Dinh)

17 0.75 1.48 -do- 5.05 0.17

Cam Ranh (Khanh Hoa)

17 1.35 1.24 -do- 4.55 0.19

Trung Phong (Binh Thuan)

14 1.18 1.86 -do- 6.15 0.32

Ninh Hai (Ninh Thuan)

10 0.93 0.91 -do- 6.95 0.31

Soil type

Lam Cong Dinh (1963) Nguyen Xuan Quat, Hoang Xuan Ty Soil provenanceperties growth Growth of casuarinas

Soil texture

pH DH (m/year)

DD (cm/year)

DH (m/year)

Tree form (%) Good Medium Poor

Foreshore sandy soil

Loose sand

6.1 1.75-2.35 1.20 1.56 59.2 28.3 12.5

Fixed sand -do- 6.0 0.90-1.50 1.08 1.22 - 66.7 23.7 Moving

sand -do- 6.2-

7.0 0.10-0.50 0.57 1.30 2.0 20.8 77.2

Page 7 of 16

Cobang ngang

Table 63- Height growth rate of casuarinas cultivated on sandy soils at sites of different distances from sea-shore

(Hoang Xuan Ty-1996)

Table 64-Growth of casuarinas on coastal sandy soils with different water drainage conditions.

Observations - Research on the growth of casuarinas under different conditions of: soil types/subtypes, sand mobility (fixed or moving sand dunes), distances from sea-shore, water drainage..., mainly in zones/regions where coastal sandy soils extend over large areas, yields the following four relationships, that can be used as measuring sticks for soil

Distance from sea-shore (m)

Sandy soil type Growth of casuarinas of 8 years of age H (stand in m) H (m/year)

50-100 Foreshore sandy soil 11.8 1.47 160-200 Sandy soil on flats,

good drainage 8.0 1.00

200-400 Sandy soil on flats, good drainage

6.7 0.84

1.000 Fixed sand dunes for from seashore

3.5 0.43

Coastal sandy soil type Depth of water-table (cm)

Water drainage Stand growth (casuarinas of years)

H (cm) DH (m/year)

Sandy soil on flats, good drainage

>60

Good

6.7

0.84

Fixed sand dunes for from sea-shore

30-60

Poor

3.5

0.44

Sandy soil on flats, with water logging in rainy

season+gley layer

0-30

Very good

2.5

0.31

Sandy soil on flats, water logged in the rain season,

during month

0

Water-logged

Dead

-

Page 8 of 16

productivity assessment. 1- Concerning sandy soil types/subtypes being developed under different conditions of geological age and parent materials-either sedentary or water wind-borne-it can be observed that casuarine growth and growth rate seem to go better and better through the series of: white sandy soils and sand dunes< yellow sandy soils and sand dunes < Red sandy soils and sand dunes <coastal alluvial sandy soils < coastal coral and sea-shell sandy soils. However, under the present setting, most of the last two sub-types are used for agriculture farming (tree crops are only grown on these for farm crop protection, in particular against moving sand); 2/ Regarding the rate of mobility of sand-hills and its limitation on the growth of Casuarinas, it is found that Casuarina growth goes worsening through the series of fixed sandy soils and sand dunes > low and moderately moving sandy soils and sand dunes > highly moving sandy soils and sand dunes. 3/ Water drainage conditions of sandy soils (being in close relationship with the water table next to or far away from soil surface) have their strong impacts on the growth of Casuarinas established; they can be described as follows: with better plant growth being found on soils of good drainage. Sandy soils with good drainage > sandy soils with poor drainage > sandy soils with very poor drainage and temporary waterlogging during the rainy season. For sandy soils of very poor drainage and those with water table next to the soil surface (0-30 cm) and with prolonged waterlogging during the rainy season, the practice of “raised bed” in checkered cropping pattern can make them suitable to farm crops with tree crops used only as protective crops there ; and 4/ The location of sandy soils in relation to their distances to the sea. On the other hand, proves to be of much relevance to Casuarina plantations, because of its relationship with the soil formation process and the leaching of nutrients occurring on these types /subtypes of soils. Casuarinas growth worsens through the chain of: Foreshore sandy soils > sandy soils at an intermediate location > sandy soils far away from the sea (or inland sandy soils). 3.3.1.2/ Assessment of sandy soils in terms of their use in forestry

Table 65: Levels of suitability of sandy soils for land use in forestry

a/ Red sandy soils and sand dunes

b/ Yellow sandy soils and sand dunes

c/ White sandy soils and sand dunes

S1a Suitable

S2a Low level of suitability

S3a Limitations

Fixed sandy soils and sand dunes Low and moderately moving sandy soils and sand dunes

Highly moving sandy soils and sand dunes

Sandy soils and sand dunes, good drainage

Sandy soils, poor drainage Sandy soils, very poor drainage with temporary waterlogging

Foreshore sandy soils Sandy soils at an intermediate location

Sandy soils far away from the sea, inland sandy soils

S1b Suitable

S2ab Low level of suitability

S3b Limitations

Fixed sandy soils and sand dunes Low and moderately moving sandy soils and sand dunes

Highly moving sandy soils and sand dunes

Sandy soils and sand dunes, good drainage

Sandy soils, poor drainage Sandy soils, very poor drainage with temporary waterlogging

Foreshore sandy soils Sandy soils at an intermediate location

Sandy soils far away from the sea, inland sandy soils

S1c Suitable

S2c Low level of suitability

S3c Limitations

Fixed sandy soils and sand dunes Low and moderately moving sandy soils and sand dunes

Highly moving sandy soils and sand dunes

Sandy soils and sand dunes, good drainage

Sandy soils, poor drainage Sandy soils, very poor drainage with temporary waterlogging

Foreshore sandy soils Sandy soils at an intermediate location

Sandy soils far away from the sea, inland sandy soils

Page 9 of 16

3.3.1.3/ Steps to follow in the assessment of the potential productivity of coastal sandy soils for use in forestry

For that purpose, the following steps are to be carried out : Step 1: Map reading: using soil maps available in Hanoi and many other provinces scaled at 1/250,000 to find out: *Areas of coastal sandy soils suitable for agricultural farming, they include area of: · Sandy soils with very poor drainage;

· Sandy soils being waterlogging during the rainy season (with gley layers);

· Alluvial sandy soils (or loamy sand); and

· Coral and sea-shell sandy soils.

*Areas of coastal sandy soils suitable for use in forestry, i.e. the remaining sandy soil area, in which the following types and subtypes can be found:

· Foreshore sandy soils for the plantation of Casuarinas for fuelwood production and for fixation of sand and sand dunes moving inland;

· Small sand-hills and sand-dunes to be used for sand fixation; · Fixed sandy soils and sand-dunes; and · Coastal sandy soils with good drainage (to be used for the plantation of Casuarinas for fuelwood production

and/or soil improvement. Step 2: It is carried out, based on the existing vegetation cover on coastal sandy soils, to find out areas of: · Fixed sandy soils and sand dunes (based on the natural vegetation cover of shrubs, high grasses, and /or on man-

made forests now covering almost completely the areas under study); · Low and moderately moving sandy soils and sand dunes (with vegetation covering nearly 50% of the areas under

study); and · Highly moving sandy soils and sand dunes (no vegetation cover). Step 3: It is carried out, based on existing topographic maps, to find out land forms governing the drainage of the sites (low or high water table) and the process of waterlogging. Step 4: It is designed to find out the location of sandy soils and sand dunes next to the sea or far away from it. The four steps of assessment are all important, being closely related with each other. However the first three are the most important ones. Unfortunately local conditions do not allow us to have a full assessment of coastal sandy soils and sand dunes in terms of their mobility, their micro-relief and their chemical properties; therefore an accurate assessment of sandy soil productivity for use in forestry still remains to be made. 3.3.2/ First results obtained The following results based on existing data, are only given as reference and for a first study of the matter Table 6: Preliminary results on the assessment of potential productivity of coastal sandy soils for use in forestry (types/subtypes of soils and their area)

Type of soil Location

White and yellow dunes

(ha)

Red sand dunes (ha)

Coastal sandy soil (ha)

Coral sandy soil (ha)

Cultivated sandy soils

(ha)

Total area (nation wide):502,045 ha

159,126 77,017 233,754 545 39,603

1 Midland &mountain area in

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Sources: - Agriculture Planning and Engineering Institute (1980) - Lam Cong Dinh (General Direction of Forestry 1963-1968) - Forest Science Institute of Vietnam (1985,1995,1996) 3.4/ Use of coastal sandy soils and sand dunes in agriculture, and forestry based on a preliminary assessment of their potential productivity. 3.4.1/ Economic and social conditions.

Prevailing in coastal areas is a moderate population density,with 30% of the total living on fishery and the rest-go-70% of the total being farmers depending for subsistence on incomes from agriculture and forestry.

· Gradually forestry has gained momentum in communities living along the coasts, with local people’s households, producing forest tree seedling’s, planting Casuarinas on a regular basis for protection against moving sand, for timber production and even for soil improvement. In some areas, in particular at the commune of Binh Duong, in the district of Thang Binh (province of Quang Nam), more than one household have got good incomes from Casuarina timber and fuelwood-of above 50-60% of their total earning-thus showing examples to many others.

· Following this, cattle rearing has also been developed with breeds well adapted to the coastal sandy conditions where sand, wind and solar heat always have their limiting effects on animal and men life and where grasses do not abound.

· The consumption and demand of timber and fuelwood, in particular of fuelwood, for house construction and food cooking, especially under the post-war conditions, become something very urgent asking for immediate solutions.

The above-mentioned economic and social background has made the cultivation of Casuarina in the area a “must”, because of its benefical impacts:

· Casuarina grows very fast in its young age 2-3 years after plantation; when growing in high but still appropriate denoity, it can quickly protect the soil, thus preventing sand from moving and threatening farm crops, home gardens, farm-houses, not excepting animal and men life and many other community social activities, and thus paving the way to sustainable land farming along the coasts.

· Casuarina bark and leaves can be used to make composts to help farmers better grow agricultural crops on sandy

Northern provinces: 8,972ha

- - 8,972 - -

2 The red river delta 4,709 ha

- - 4,709 - -

3

The former 454

zone: 150,502 ha

Moving sand dunes: 1,000 (south of Ha Tinh)

149,582

219

-

4

Coastal south central Vietnam

region: 264,981ha

114,744 (of which

100,000 ha are moving sand dunes)

77,017 (of which 38,000

ha are moving sand

dunes)

42,891

326

-

5

Eastern south Vietnam 22,671 ha

5,554

17,127

-

-

6

The Mekong delta 49,717ha

425

9,689

39,603

Page 11 of 16

soils.

· Casuarina can produce modules in its root systems for nitrogen fixation from the atmosphere, through not being a leguminous species.

· Casuarina as fast-growing evergreen timber species cannot produce durable timber, butunder the present setting can yield timber of value for uses in coastal sandy areas. A Casuarina tree of 20-25 cm Dbh (12-15 years after its plantation) can be sold at VND 60,000-70,000 (the equivalent of 40kg-50kg of rice) at local market places.

Used as fuelwood, Casuarina is highly appreciated by local farmers, because of its high calorific value (4,950kcal/1kg) (NAS,1980) and its capability to burn easily even when fresh cut. Casuarina fuelwood is highly in demand on local markets along the coast, it fetched at a price of VND 250,000-300,000 a “ster” (=stocked cubic metre); and its fuelwood production in the provinces of Quang Nam and Da Namg amounted to 670,000 cu.m per year (Ha Chu Chu, Le Dinh Kha-1996).

· Protective belts of Casuarinas established along the coasts can also help improve local environments: they have strong impacts on lowering air temperatures during hot days, on keeping warmer temperature during the night in winter, maintaining the water table high enough to provide water for uses in agriculture production and many other domestic uses.

3.4.2/ Land use principles to usher in sustainable agro-forest production in coastal sandy soil areas.

· Shelterbelts capable of getting established as soon as possible after plantation and well distributed over moving and fixed sand areas are necessary for effective protection against the ravages caused by moving sand-hills.

· It is also necessary to create conditions for environmental improvements to lower the excessively high temperatures on sandy soil surface occurring in hot summer, and prevent acute shortage of water in the dry season.

· Forestry activities for crop and animal protection should come first so to create pre-conditions for agriculture and animal husbandry development in the areas.

· Good and close relationships between forestry and agriculture in coastal sandy areas should be kept so to establish an organic whole, with the one supporting the existence and functioning of the other and vice versa.

· Activities/projects should be designed to continually increase the yields of agricultural crops on sandy soils on a sustainable basis and at the same to produce small timber and fuelwood for uses by local farmers.

· Soil productivity/fertility should be maintained and further improved continually over time.

3.4.3/ Criteria for the selection of forest tree crops for environment protection on coastal sandy soils.

Page 12 of 16

The tree species selected for the purpose should:

· Grow fast in their young age.

· Be resistant to strong winds and capable of sprouting strong and wide-spread roots to keep them well erect on sandy soils;

· Be well adapted to a wide range of soil fertility, in particular to sandy soils poor in mineral nutrients and organic matter and also to very wet or very dry sites.

· Be of soil-improvenanceving species, capable of nitrogen fixation from the atmosphere; and

· Produce timber and/or fuelwood of much relevance to local farmers.

Research, studies and trials have been made for many years in the areas to use and grow:

- Casuarinas (Casuarina equisetifilia)

- Acacia auriculaeformis;

- A. mengium;

- A. crassicarpa; + other acacias

- Eucalypts; and

- Cassia siamea (vernacula Muong den)

The merits of Casuarinas when grown on coastal sandy soils have been discussed at length earlier. Casuarinas prove to have met the fixe criteria for selection as presented above.

· However, the further enlarge the range of Casuarina cultigens for plantation establishment along the coast in 1994-1995, the Plant Breeding Center of the Forest Science Institute of Vietnam, carried out a series of provenance trials with 52 provenances of Casuarina equisetflolia at a number of sites along the coasts of Vietnam, from Binh Thuan, Quang Nam, Da Nang to the northern provinces of Nghe An and Thanh Hoa.

After two years, the trials show the following results:

1/ At the site of Bau Da in the district of Tuy Phong, (province of Binh Thuan) where semi-arid climate prevails with the following characteristics:

- Annual mean temperature within the range of 2705C

Page 13 of 16

- Mean annual precipitation of 700mm

The trials were made with:

· The provenance no.16166 (from Danger P.t.N.T, Australia), scoring a high survival rate of 74% and yielding the best performance;

· The provenance no. 18014 (from Haingera, Balukhand, State of Orissa, India); and

· The provenance no. 18152 (from Minh Chu, province of Binh Thuan, Vietnam).

The last two provenances yield only next best performances.

2/ At Binh Minh, in the district of Thang Binh (Quang Nam), the following provenances show the best results.

· Provenance 18297 (from Ban Kam Thuam, Ranong, Thailand);

· Provenance 18287 (from Hambantota Srilanca);

· Provenance 18312 (from Efate Island, Vanuatu); and

· Provenance 18121 (from Mariana Island, Guam).

3/ At Nghi Xuan, Nghi Loc (Nghe An) the provenance 18117 (from San Jose, Midoro, the Philippines) performs very well.

4/ At the commune of Quang Hung district of Quang Xuong (Thanh Hoa), the following provenances show the most promising results:

· Provenance 18296 (from Ban Bong Sak, Phangnga, Thailand);

· Provenance 18152 (from Minh Chu, Binh Thuan, Vietnam);

· Provenance 18355 (from Cotonou, Benin);

· Provenance 18119 (from Remiswaram, Temil Nadu, India);

· Provenance 18288 (from Madagama, Srilanca); and

· Provenance 18299 (from Had Samira, Songkhla, Thailand).

Page 14 of 16

Nevertheless, the early results of only two year provenance trials carried out by Phi Quang Dien (Forest Science Institute of Vietnam-1996) with 52 provenance of Casuarinas still have to experience the acid test of time before they can be used at large under field conditions.

Moreover, other Casuarina clones-named as clone 701 and clone 601 (in particular clone 701)-imported from China by the Forest Protection Station no. 2 of Thanh Hoa, have been tested with succes. They are found to be very promising on coastal sandy soils of Vietnam.

Casuarinas are also cultivated as shade trees and decorative plants at a number of seaside resorts in this country.

* A number of acacias were also under tests and trial in Vietnam. Among them, Acacia crassicarpa seems to be well adapted to conditions prevailing on local sandy soils, (in particular on inland sandy soils).

For example: at Dong Phong in the province of Thua Thien Hue, on island sandy soils, A. crassicarpa has scored a survival percentage of nearly 100% and thrived very well, at a rate of two times better than Acacia mangium.

In the semi-arid area, of Ninh Thuan and Binh Thuan adverse conditions prevail, and in 1998 some 1,000 hectares planted with Acacia auriculiformis died. Thus asking for further studies of drought-resistant acacias. Research and studies made by Prof. Le Dinh Kha (Forest Science Institute of Vietnam) since 1993 show that: Acacia torulosa, A. difficilis, and A. tumida (Le Dinh Kha, 1998) can get adapted to the conditions prevailing there, whereas under the same conditions Acacia auriculiformis scores a rate of survival of only 5.3%.

Among the acacias found to be suitable to the semi-arid conditions, Acacia difficilis through scoring a lower survival rate than A. torulose, grows better, and as such can be used for fuelwood production and soil improvement in the coastal areas of semi-arid climate.

However, acacias though being fast growing and capable of nitrogen fixation from the atmosphere, and producing timber of market values of the same order (i.e. of dong 360,000-400,000 per cubic metre) as eucalyptus, not behave as well as Casuarinas under the conditions of moving sand; they have their leaves torn and destroyed by fast moving sand grain, and their root systems are not strong and well-spread enough as those of Casuarinas. Therefore, it is advisable not to grow acacias for the purpose of crop protection, fixation of moving sand dunes in particular in the windiest areas, and also on foreshores next to the sea water line. Acacias seem to be most suitable for use on inland sandy soils in semi-arid areas.

For eucalyptus grown on coastal sandy dunes, the following observations can be given:

· Because of their small and open crowns, eucalyptus can poorly protect agricultural crops against strong sea winds; and

· They cannot improve sandy soils.

As a result, they are used in small areas, or mixed (only in low percentages) with Casuarinas in shelterbelts along the coasts, because of their fast growth, their timber and the quick incomes they can afford to local farmers.

Page 15 of 16

Recent studies with six eucalyptus species and 32 provenances made at Dong Ha (province of Quang Tri) show that Eucalyptus urophylla, provenance Lembata, yields the most promosing performance. After four years in trial plantations, Eucalyptus urophylla can produce a standing volume of 33.17 dm3 per tree, as compared to 13.98 dm3/tree produced by E. camaldulensis provenance Petford and only 10.25dm3/tree by E.camaldulensis, of Nghia Binh provenance.

On the other hand, Cassia siamea (vernacular Muong den) under tests and trials on coastal sandy soils shows slow growth in its young age, and no fixation of nitrogen, in spite of being a leguminous species.

Another tree crop of interest for export cashew (Anacordium occidentale) should be mentioned here.

· It is a typical tropical cash crop to be used on coastal sandy soils, because of its low resistance to long spells of cold, and very high resistance to drought, and its adaptability to marginal land lacking soil nutrients. Therefore it is a godsend for local communities and people living in the arid coastal sandy soil area of Binh Thuan and Ninh Thuan.

· Cashew grown in Northern provinces does not thrive well and bear fruit. For example, when grown in Quang Nam and Da nang, cashew yields poor harvests; then further North, in Quang Tri province, cashew yields almost no harvests. It performs well only when grown south of Quang Ngai to produce harvests for export.

· Under these conditions, cashew farming should be regarded as best in the semi-arid coastal sandy soil area of Binh Thuan and Ninh Thuan.

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Page 16 of 16

Chapter 4

Assessing the productivity of mangrove saline and sulphate soils in the Mekong Delta.

4.1/ Bases for assessment.

Forest land in the Mekong Delta include mangrove saline soils and acid sulfate soils; other fertile alluvial soils are regarded as agricultural land. Normal assessment procedures as presented earlier, using the four (4) component factors, cannot be applied because such factors as slope, soil depth and soil texture when conventionally used are of no help in the assessment process as they are all of the same class (class 1). Therefore, other criteria/ approaches, which are closely related to land productivity and use in forestry in the Mekong Delta, should be chosen. For forest land assessment in the Mekong Delta, besides factors related to soil fertility, it is much more important to pay attention to factors affecting land use, because in more than one circumstance, they do not agree with each other. For instance, the high organic matter content in sulfate soils very often cause serious limitations in use, and their use through improvements may have detrimental impacts on the environment. The following grades are set for use in assessment: -Grade 1: Land of high productivity, the use of which does not meet with any limitations, when using only easy methods to promote its natural productivity; in short it is very suitable for forest land use; -Grade 2: Suitable for forest land use with some limitations; and -Grade 3: Serious limitations to forest land use, requiring specific methods of soil improvement/cultivation before use or poor productivity. Assessment does not rely on the marks given, but on the selection of key factors and aspects affecting land use, as shown below. 4.1.1/ The case Mangrove saline soils. The factors first used for assessment are: -Soil type -Soil texture -Soil age; and -Organic matter content. a/ Soil type Referring to soil maps available for the region, one can find the following soil types: + Mangrove saline soil Mm: first assessed as of grade 2; and + Mangrove sulphate soils with sulfide material found at variable soil depths known as Sp1 Mm and Sp2Mm. b/ Soil texture: First assessment is made based on the following: +Loam: assessed as of grade 1 +Clay: assessed as of grade 2; + Sand and sandy soil assessed as of grade 3 (the type is found along the coasts of Ha Tien). c/ Soil age: A first assessment is made based on the following: +Soil clay and clay: grade 1 + Muddy soil: grade 2 + Compact soil: grade 3. d/ Organic matter content: first assessment based on: +Organic matter content: less than 8%: grade 1 + Organic matter content: 8-15%: grade 2 + Organic matter content: above 15%: grade 3. For a final assessment, the soil age and soil texture as observed in field survey following the characteristics mentioned above are used. However, on maps there are no indications of soil age; and for soil texture there is only one class. All these make us refer to the existing vegetation type as important indicator for a final assessment of mangrove saline soils, and of the land on which they occur: + Muddy mangrove saline soils with the occurrence of Avicennia alba (vernacular Mam trang) as pioneers Grade 2 (suitable)

Page 1 of 6

of foreshore. + Same bordering rivers and canals, but showing an older age with the occurrence of A. officinals (vernacular Mam den). + Soft clayey concealed acid sulfate mangrove saline soils with the occurrence of Rhizophora apiculata Grade 1 (very suitable) (vernacular Duoc) + Clayey concealed acid sulfate mangrove saline soils + Compact clayey concealed acid sulfate mangrove saline soils with Grade 3 (very suitable) the occurrence of Ceriops and Excoecaria agaliocha 4.1.2/ The case of acid sulphate soil. First assessment is made based on five (5) criteria: a/ Soil type: using available soil maps to find out the depths at which the acid sulphate layer can be noticed: + Shallow active acid sulphate soils (Sjl) and peat concealed acid sulphate soils (TS): grade 2 + Saline shallow active acid sulphate soils (SjM): grade 3 b/ Organic matter content (inferred from vegetation indicator): + < 8%: grade 1 + 8-15%: grade 2 + > 15%: grade 3. c/ Duration under water: + Waterlogged for less than 3 months: grade 1 + Waterlogged for 3-4 months: grade 2 + Waterlogged for more than 4 months: grade 3 d/ Depth of waterlogging: + Less than 60 cm: grade 1 + Between 60 and 100 cm: grade 2 + More than 100 cm: grade 3. e/ Availability fresh water for flushing down sulphates: + Grade 1: easy fresh water supply; + Grade 2: Difficult fresh water supply; + Grade 3: very difficult fresh water supply. All criteria c, d, e can be identified on agro-hydrological For a final assessment, the following criteria play a very important role: + Depth of waterlogging + Conditions of fresh water supply for flushing down sulphate. 4.2/ Assessment of forest land productivity in the Mekong Delta 4.2.1/ Mangrove saline soils Table 52:

Location

Total area

Grade 1 (very suitable)

Grade 2 (suitable)

Grade 3 (apparent limitations)

Area (ha)

% Area (ha)

% Area (ha)

% Area (ha)

%

Mekong Delta

221,675 100 19,951 9.0 110,837 50 90,887 41

Minh Hai 163,818 73.9 19,956 12.1 107,628 65.7 36,368 22.2 Ben Tre 19,720 8.0 19,729 100 Kien Giang 13,300 6.0 1,662 12.5 11,638 87.5

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Notes: There are no mangrove saline soils in the five provinces of Dong Thap, Can Tho, An Giang, Vinh Long and Long An. (In Long An, there are some 700 hectares of mangrove saline soil, which cannot be presented on the soil map scaled at 1/250,000)

The final assessment goes on follows: Mangrove saline soils in the Mekong Delta rated as of grade 1, very suitable for the plantation of mangroves (mainly Rhizophora spp.) account for only 19,951 hectares (=9%); they are found only in the province Minh Hai (Table 52). On these sites, Rhizophora plantations can yield up to 10-12 cu.m/ha/year.

Mangrove saline soils rated as of grade 2 (suitable for forest land use) extend over larger areas (110,837), accounting for 50% of the total; they are also found mainly in the province of Minh Hai (where they occur on 107,628 hectares) -Appropriate management of these soils can make them yield up to 7-10 cu.m/ha/year. Mangrove saline soils of grade 3 (showing apparent limitations) extend over 90,887 hectares (=41% of the total area); yield of mangroves established on these soils will be below 7 cu.m/ha/year and plantation on them can only survive after many replacements of deal seedling. 4.2.2/ Acid sulphate soils.

Table 53: Assessment of acid sulphate soil productivity in the Mekong Delta region

- Acid sulphate soils rate as of grade 1 for forestry development cover a very small area, only 1,673 hectares (=0.5% of the total); they are found in Minh Hai province;

- The same rated as of grade 2 extends over 157,247 hectares (=47% of the total); and - The same rated as of grade 3 extends over large area of 175,648 hectares (= 52.5%of the total). Some ten

thousand of hectares of land of this grade cannot be regenerated using Melaleuca spp. large amount of labour should be used there for bed raising for the cultivation of Eucalyptus tereticornis.

A consolidated statement on forest soil productivity and land use in the Mekong Delta reads as follows: (Table 54) - There is only a very small area of forest soils in the Region which can be rated as of grade 1 (20,581 hectares), of

which 19,951 hectares (=97% of total area in this grade) of mangrove are found in Minh Hai province. - Forest soils in the region rated as suitable (grade 2) for forestry development amount to 267,830 hectares

(=46.7%). They are mainly found in the provinces of : + Minh Hai: 144,054 hectares; + Kien Giang: 59,554 hectares; + Long An: 15,674 hectares...

- Forest soils in the region showing apparent limitations to forest development (grade 3) account for 267,830 hectares (=48%); they are mainly found in the provinces of: + Minh Hai :76,662 hectares; + Kien Giang: 65,823 hectares; + Dong Thap: 23,529 hectares...

Tra Vinh 9,975 4.5 9,975 100 Soc Trang 8,202 3.7 1,662 25.0 8,202 100 Tien Giang 6,650 3.0 4,988 75.0

Location

Total area

Grade 1 (very suitable)

Grade 2 (suitable)

Grade 3 (apparent limitations)

Area (ha)

% Area (ha)

% Area (ha)

% Area (ha)

%

Mekong Delta

334,568 100 1,673 0.5 157,247 47 175,648 52.5

Kien Giang 109,069 32.6 56,061 51.4 53,008 48.6 Minh Hai 81,735 24.4 1,673 1.0 39,931 48.9 40,132 49.1 Long An 31,784 9.5 15,129 47.6 16,655 52.4 Dong Thap 30,278 9.0 7,569 35.0 22,709 75.0 Can Tho 24,129 7.2 7,552 31.3 16,577 68.8 An Giang 22,756 6.8 6,474 26.7 16,277 73.3 Vinh Long 12,111 3.6 7,569 62.5 4,542 37.5 Soc Trang 9,033 2.7 6,025 66.7 3,008 33.3 Tien Giang 6,056 1.8 4,542 75.0 1,514 25.0 Tra Vinh 3,011 0.9 3,011 100 Ben Tre 3,011 0.9 3,011 100

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Table 54- Consolidated statement on land evaluation in the Mekong Delta.

4.3/ Use of Mangrrove Zones In The Mekong Delta. 4.3.1/ The case of mangro saline soil and its zone. For better use of the land with mangrove saline soils, the first thing to do is to restore as quickly as possible the natural forest and water resources there. It is necessary to protect the zone biodiversity in terms of its flore and fauna, its specific ecosystems and the structure of these systems which have been developing there for ages to counter sea water and wind erosions for better farm crop protection and for the process of land building and coast extension to go on over time; all of which can provide very good conditions not only for agriculture and forestry to develop, but also for scientific research and not the least for tourism development. · Efforts should be made: + To protect and establish tidal mangroves for:

- The stabilization of foreshore at estuaries through the planting and maintenance of Avicennia alba (vernacular Mam trang);

- That of sea-shore through the establishment of mangroves (Rhizophora spp) which, because of their prop roots, can reduce tidal currents and cause extension deposition of mud and silt.

+ To protect and establish protective belts of mangroves along canals and watercourses to prevent sea-shores and river banks from being gullied or eroded. For instance the planting of Avicennia officinalis (vernacular Mam den) in combination with Nipa (Dua nuoc) can create two stories of trees in the stands established, with the first story being occupied with Avicennia and the second are with Nipa, thus creating atends of mangroves that can help mud and silt get deposited and then not be eroded away. The lay-out of these protective belts should be made to suit the local physical conditions of the area under protection; in some cases they can extend up to 200 m wide for adequate protection. Along canals and watercourses shelter belts of mangroves can be of 50 m wide. + To protect and establish extensive plantations of Rhizophora spp. In the Mekong Delta, over extensive areas of tidal and intertidal mangroves, the planting of Rhizophora apiculata (vernacular Duoc) can be carried out with success, using appropriate technical procedures as required by specific site conditions, which may cause some problems to occur. Stereotyped management in the region has caused the scarcity and then the loss of a number of interesting tree species such as Bruguicra (vernacular Vet) ..... (vernacular Dziu), Lumnitzera (vernacular Coc), and .... (vernacular Dung)....

· Protection should also cover a wide range of tree/plant species, which in the Mekong Delta can thrive only under restricted conditions of sunlight, soil and tidal regime, in particular:

Avicannia alba (vernacular Mam Trang) can grow well only on ....... Loose muddy sea-shore; Avicennia officinalis (vernacular Mam den) can grow best only on ....... Deposited muddy soil along canals and watercourses. Rhizophore spp (vernacular Duoc) thrive well on ....... soft clayey soil; Brugniera spp grow well on ....... Clayey soil; and Ceriops (vernacular Gia) ..on ...... Compact clayey soil. · As the mangroves and their soils can change very much from sites to sites within limited tracts of land, the

stands to be established should be made to vary with the site conditions: therefore we can establish: - Pure plantations of mangroves; - Mixed plantations of mangroves, either:

+in rows; or + in strips; and

- Multi -storied mixed plantations of mangroves; and

Location Total area Grade 1 (very suitable)

Grade 2 (suitable)

Grade 3 (apparent limitaions)

Provinces Area (ha) % Area (ha) % Area (ha) % Area (ha) % Region 556,241 100 20,581 3.7 26,830 482 267,830 48.2

1-Minh Hai 241,297 43.38 20,581 8.5 144,054 59.7 76,662 31.8 2-Kien Giang 125.377 22.54 59,554 47.5 65,823 52.5 3-Long An 32,929 5.92 15,674 47.6 16,255 52.4 4. Dong Thap 31,372 5.64 7,843 25.0 23,529 75.0 5-Can Tho 25,086 4.51 7,824 31.2 17,259 68.8 6- An Giang 23,529 4.23 6,287 26.7 12,247 73.3 7- Ben Tre 21,916 3.94 3,134 14.3 18,782 85.7 8-Soc Trang 17,243 3.10 6,276 36.4 10,968 63.6 9-Tra Vinh 12,515 2.25 2,129 25.0 10,386 75.0 10-Vinh Long 12,515 2.25 7,822 62.5 4,693 77.5 11-Tien Giang 12,515 2.25 6,257 50.0 6,257 50.0

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- Plantation of mangroves in combination with shrimp culture. One of the most lucrative farming systems in mangrove areas along the coasts-in particular of South Vietnam- is to carry out fish and/or shrimp farming under mangroves. The practice can help restore the vegetation type which has naturally occurred in the zone in case of good management aiming forward at social forestry, for which both fishery and forestry can be combined for the benefits of local people living in the area, when the following farming principles are adopted:

· In mangrove areas endowed with loose and muddy foreshores being affected by diurnal tides more than 25 days a month and under deep water,

· In mangrove areas endowed with muddy soil being affected by diurnal tides from 21 to 25 days a month and under deep water,

· In mangrove areas endowed with soft clay or clay soil now being affected by diurnal tides from 10 to 20 days a month,

· Regular shrimp farming can be practised with standing mangroves maintained for protections.

· Some kind of forestry and fishery can be combined with each other to create a “shrimp-mangrove system” to

be run on a regular basis. · Management of mangrove stands will be carried out as the main farming system in which shrimp culture can

be practised as a side-activity following the formular: mangroves first next come shrimps. 4.3.2. The case of sulphate soil and its zone. The management and use of forest land affected by acid sulphate soils is summarized in Table 55.

Table 55- Summing up sound practices for the use of sites affected by acid sulphate soils in the Mekong Delta.

Grade Area (%) Types of acid sulphate soil Main principles for use Grade 1

(very suitable) 1,673 (0.5%)

Shallow active acid sulphate soil, waterlogged with less than 60,000 under waterready supply of fresh water, and surrounded by an adequate network of canals for water drainage.

- Easy flushing down of sulphates, therefore the site can support the cultivation of swamp rice and many other crops, including fruit crops, the established plantation of Melalauca leucademdron thrives well.

- Can be subdivided into two subtypes with different farming systems · Under 0-30cm of water: swamp

rice +Melaleuca; · Under 30-60cm of water: fresh

water fish+swamp rice+ Melaleuca. Grade 2 (suitable)

157,247 (47%)

- Shallow active acid sulphate soil, waterlogged under 60-100cm of water.

- Peat acid sulphate soils with sulphates capable of being flushed down following the construction of canal network.

- Melaleuca stands perform well if floods can flush down sulphates and enough silt and mud can get deposited on sites.

- Melaleuca stands perform moderately well in flats causing deposition of sulphates.

- Possibility of carrying integrated fishery forestry farming systems with: swamp rice+Melaleuca+fresh-water fish farming+ Bee keeping.

Grade 3 (Apparent limitations)

175,648 (52.2%)

- Shallow active acid sulphate soil, waterlogged under 100-200cm of water;

- Peat+acid sulphate soil, waterlogged under 100-200cm of water.

- Saline shallow active acid sulphate soil.

- Facilities for sulphate flushing down inexisting, for want of fresh water and

- Waterlogged under 100-200 cm of water and more.

- Accumulation of sulphates + difficult conditions for sulphat flushing down.

Active acid sulphate soil (because of the presence of sulphate layer next to soil surface)+no conditions for sulphated flushing + waterlogged with less than 30cm under water: Melaleuca growth will be very poor and under the threat of being destroyed by wild fire. Raised bed is necessary for

Page 5 of 6

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canals for water drainage plantation of Eucalyptus cameldulensis and/or E.tereticornis (swimp rice and fish culture cannot growth here). - Melaleuca stand+swamp rice+fish

culture giving low yields (in the case of the site being 100-200cm under water).

- Melalueca +fish culture on sites with >200 cm under water: yields remain poor.

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Chapter 5

Assessment of site suitability for the cultivation of tree crops

Dr. Hoang Xuan Ty when carrying out a national research project during 1986-1990, has pointed out in quite concise way the site suitability for the cultivation of some important tree species such as: Pinus merkusiis, P. massoniana, P. khasiya, Anacardium occidentale, Eucalyptus tereticornis, E. camaldulensis, Acacia auriculifomris... In his work, Dr. Hoang Xuan Ty has made a nation-wide assessment and used methodologies well-known the world over to sort out levels of suitability, using appropriate application on computer. Our methods do not differ much from his. We only add some more criteria for levels/classes identification and our assessment is made following a region approach (economic regions), some of which have not had any forest plantations so far. We also take this opportunity to lay emphasis on the criteria used for determination and to give some general observations. Our concepts on the levels/degrees of suitability S1, S2, S3 and N have been presented elsewhere in this paper, in which S1 means very suitable (=optimal conditions), S2 suitable, S3 of medium suitability and N or S4 not suitable or marginal to the tree crop under study. 5.1/ Criteria for site suitability evaluation

5.1.1/ Criteria for the determination of the levels of site suitability for the cultivation of Eucalyptus camaldulensis and E. tereticornis.

A/ Climatic conditions (Table 56)

B/ Edaphic conditions (Table 57)

Notes: A: Grey soils, yellowish brown on old alluvia; alluvial soils B: Acid sulphate soils, feralit Fk, Fs, Fa, Fq C: Sandy soils, feralit on limestone Fv, semi-acid brown soils D: Saline soils, sand dune, black soils, humic soils on mountain, eroded soils

Levels of suitability

Climatic factors

S1 S2 S3 S4 or N

Annual mean

temperature (oC)

24-27

22-24

20-22

<20

Lowest mean

temperature (oC)

> 18

14-18

12-14

12

Highest mean

temperature (oC)

34

32-34

30-32

30

Annual rainfall

>1,800

1,400-1,800

800-1,400

<800

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea level (m)

< 100

100-300

300-500

Ø 500

Soil depths (cm) > 100 50-100 < 50 Slope (oC) < 15o 15-25o 15-25o > 35o

Page 1 of 7

5.1.2/ Criteria for the determination of the levels of site suitability for the cultivation of Acacia auriculiformis A/ Climatic conditions (Table 58)

B/ Edaphic conditions (Table 59)

Notes: A: Grey soils: yellowish brown on old alluvia; alluvial soils; reddish brown on basalts, schists; B: Acid sulphate soils; reddish brown on limestone; yellowish red on acid magma and sandstone; black soil; brown soil; C: Coastal sand: red sand; eroded soils, reddish yellow humic in soil D: Saline soils; humic soil on high mountain peaty gley; rocky mountain. 5.1.3/ Criteria for the determination of the levels of site suitability for the cultivation of Acacia mangium A- Climatic conditions (Table 60)

Levels of suitability

Climatic factors

S1 S2 S3 S4 or N

Annual mean

temperature (oC)

> 25

23-25

20-23

<20 Hottest month mean

temperature (oC)

> 32

30-32

28-30

<28 Coldest month mean

temperature (oC)

>18

14-18

12-14

<12 Average annual rainfall

>2,000

1,500-2,000

1000-1,500

<1,000

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea level (m)

300

300-600

600-800

Ø 800

Slope (oC) < 15o 15-25o 20-35o > 35o Soil depths (cm) > 100 50-100 < 50 Not elevant

Levels of suitability

Climatic factors

S1

S2

S3

S4 or N

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B/ Edapthic conditions (Table 61)

Notes: A: Grey soils: yellowish brown on old alluvia; feralit soils on alkaline, metamorphic and alluvial parent materials; B: Acid sulphate soils; on sandstone; red sand; feralit on limestone; C: Coastal sand: brown soil in semi-arid areas; eroded soils, D: Saline soils; humic soil on high mountain (H); reddish yellow humic soil (FH) 5.1.4/ Criteria for the determination of the levels of site suitability for the cultivation of Teak (Tectona grandis) A/ Climatic conditions (Table 62)

B/ Edaphic conditions (Table 63)

Annual mean

temperature (oC)

20-23

23-26

26-28

>28 Highest mean

temperature (oC)

30- 32

32-34

34-35

>35 Lowest mean

temperature (oC)

12-16

16-20

20-22

<12 Annual Rainfall

>2,000

1,500-2,000

1000-1,500

<1,000

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea level (m)

300

300-600

600-800

> 800

Slope (oC) < 15o 15-25o 20-35o > 35o Soil depths (cm) > 100 50-100 < 50 Not elevant

Levels of suitability

Climatic factors

S1 S2 S3 S4 or N

Annual mean

temperature (oC)

>25

23-25

21-23

<21 Hottest month mean

temperature (oC)

32- 34

30-32

30-27

<27 Coldest month mean

temperature (oC)

>17

12-17

12-10

<10 Average annual Rainfall

>1,800

1,600-1,800

1,200-1,600

<1,200

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea

Page 3 of 7

Notes: A: Alluvial soil: black soil; “feralit” soils on alkaline, basaltic, calcareous parent materials; B: Grey soils: yellowish brown soil on old alluvia; “feralit” soils on schists and metamorphic rocks;

C: “Feralit” soils on acid magma and sandstone; humic “feralit” soil on mountains D: Sandy soils, saline soil; acid sulphate soil; peaty gley; eroded soil; humic soil on high mountain. 5.1.5/ Criteria for the determination of the levels of site suitability for the cultivation of Pinus kesiya A/ Climatic conditions (Table 64)

B/ Edaphic conditions (Table 65)

Notes: A: Reddish yellow humic soil (FH); yellowish red soil on acid magma, dacite; yellowish brown soil on basalt; B: Reddish brown soil on basalt; yellowish red soil on schists;

C: Grey and yellowish brown soils on old alluvia, degraded soils on basalts; reddish brown on limestones; D: Sandy , saline soils; Acid sulphate soils, black soils, peaty soils; brown soil in semi-arid areas; eroded saline soils 5.1.6/ Criteria for the determination of the levels of site suitability for the cultivation of Pinus merkusii A/ Climatic conditions (Table 66)

level (m) 300 300-600 600-900 > 900 Slope (oC) < 15o 15-25o 20-35o > 35o Soil depths (cm) > 100 50-100 < 50 Not elevant

Levels of suitability

Climatic factors

S1 S2 S3 S4 or N

Annual mean temperature

(oC)

18-20

20-21

21-22

> 22 & < 18 Hottest month mean

temperature (oC)

<26

26-29

29-31

>31 Coldest month mean

temperature (oC)

10-11

9-10

8-9

<11 & < 8 Average annual Rainfall

1,800-2000

2,000-2,300

2,300-2,500

>2,500

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea level (m)

1,000-1,800

800-1,000

600-800

<600 & > 1,800

Slope (oC) < 15o 15-25o 20-35o > 35o Soil depths (cm) > 100 50-100 < 50 Not elevant

Levels of suitability

S1 S2 S3 S4 or N

Page 4 of 7

B/ Edaphic conditions (Table 67)

Notes: A: Yellowish red soil on acid magma, sandstone; yellowish brown old alluvia; reddish yellow humic soils; B: Yellowish red soils on alkaline magma, metamorphic and clayed material; grey soils;

C: Yellowish brown soils on basalt; red soil on limestone; eroded soils; D: Saline soils acid sulphate soils; coastal sands; black soils; humic soil on high mountains; peat 5.2/ Some early results From the criteria mentioned above and after logging the necessary date into computers, a map can be produced with region showing their suitability for the cultivation of tree crop under survey in term of their climatic and edaphic

conditions. Thus a first assessment of S1, S1, S1, S4 for the cultivation of each crop can be made for each region. The results, however, are only indicative or approximations for further studies. From the map thus produced, the following can be pointed out: -In term of climatic conditions and their relations with tree crops, one can have the chance of selecting sites of S1 (very suitable), S2 (suitable) and S3 (fairly suitable)/ suitability for the crops under consideration. -However, with regard to edaphic conditions, the same cannot be said, as there are limitations in land use in forestry, for which only are open lands and denuded hill and mountain-sides available. Under these conditions, there are few cases of using of S1, some cases of using sites of S2 and a number of cases of using sites of S3, thus hindering optimal growth of tree crops. -Therefore the main point in this exercise in a lot of cases is to centre round the selection of edaphic conditions, for which, however, the best option is to obtain sites of S3 for the tree crop under consideration. This is the reason why most plantations in this country are of very poor growth under extensive management and will probably be of poor growth even when intensive management is applied. This said, let us go on searching for sites of fair suitability for the cultivation of some forest tree crops 5.2.1/ Regions/areas suitable for the cultivation of Eucalyptus camaldulensis and E. tereticornis The results on computers show the following: going southward along the coasts of Vietnam, the climatic conditions appear to become more and more suitable (S2 to S1 conditions) for the growing of E. camaldulensis and E. tereticornis, in the particular in the East South Vietnam; S2 climatic conditions occur over 95% of its total area. S1 edaphic conditions occur in the Coastal South Vietnam region and in the East South Vietnam, in particular in Tay Ninh province. In brief, E. camaldulensis and E. tereticornis can be grown successfully (S2 conditions) in the former 4th zone (or the North Central Vietnam) and in the East South Vietnam, in particular in the provinces of Dong Nai, Tay Ninh and Song Be.

Climatic factors Annual mean

temperature (oC)

21-23

23-25

25-26

> 26 & < 21 Coldest month mean

temperature (oC)

13-14

14-16

16-17

<12 & < 20 Average annual Rainfall

>2,300

2,000-2,300

1,600-2,000

<1,600

Levels of suitability

Edaphic factors

S1 S2 S3 S4 or N

Soil types/groups A B C D Evaluations above sea level (m)

< 300 > 100

300-600

600-900

> 900

Slope (oC) < 15o 15-25o 20-35o > 35o Soil depths (cm) > 100 50-100 < 50 Not elevant

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5.2.2/ Regions/areas suitable for the cultivation of Acacia auriculiformis The same pattern as with eucalyptus can be described for Acacia auriculiformis. It suitability (S2) increases as one is going southward along the coasts of South Central Vietnam down to the East South Vietnam. Soil of S1 and S2

quality can be found in some provinces of Central Vietnam, in the former 4th zone and again in the East South Vietnam. Summing up, climatic and edaphic conditions in the East South Vietnam are fairly suitable (of S2 level)

for the cultivation of this timber species over 70% of its area; in the former 4th zone, in particular in Thanh Hoa, Quang Binh one can also find opportunity to grow Acacia auriculiformis on a commercial basis. 5.2.3/ Regions/areas suitable for the cultivation of Acacia mangium Unlike A. auriculiformis, Acacia mangium appears to encounter optimal climatic conditions (S1) in the former 4th zone and in some provinces along the coasts of South Central Vietnam such as Quang Nam and Da Nang. Further

north, it grows well (S2 condition) under the climatic conditions of Vinh Phu, Yen Bai and in the former 4th zone; but in the East South Vietnam S2 conditions prevails in smaller areas while S1 soil quality seems to have the upper hand there. In short, A. mangium seems to be suitable in some provinces of North Vietnam. Central Vietnam , in the former 4th zone the Coastal South Central Vietnam and the East South Vietnam. 5.2.4/ Site suitability for the cultivation of Pinus merkusii In term of climatic conditions, Pinus merkusii seems to encounter very suitable (S1) and suitable (S2) conditions in

Quang Ninh (of the North East), in some provinces of the former 4th zone (such as Ha Tinh, Quang Binh, Thua Thien Hue) and in some other provinces along the coast of South Central Vietnam such as Quang Nam and Da nang. On (Tay Nguyen) High Plateau P. merkusii thrives in particular in Kon Tum and Lam Dong. For edaphic conditions, the only indication of soil depth available on maps is below 50 cm, which makes detailed study of P. merkusii on the matter on computer impossible; therefore the determination of levels of site suitability in terms of soil conditions, and the consolidation of results (combining both edaphic and climatic conditions) for the species are only approximations for reference. 5.2.5/ Regions/areas suitable for the cultivation of Teak In terms of its climatic requirements, Teak can grow best (S2 level only) in the East South Vietnam, then next best on Tay Nguyen and in some provinces along the Coastal South Vietnam. However with regard to soil conditions, the areas there endowed with S2 and S3 soil quality are not extensive, covering only 12-17% of the total. As a consequence of the above, the region/areas most suitable (of S2 and S3 quality after consolidation) are found mainly in the East South Vietnam, and some other provinces of Tay Nguyen. 5.2.6/ Some useful growth data Information on the growth in a number of regions/areas of the main tree species, such as Eucalyptus camaldulensis, E. tereticornis, Acacia auriculifomrmis , A. mangium, Tectona grandis, Pinus kesiya, P. merkusii, P. massoniana, P. caribaea has been collected . Based on their height/diameter growth and their height/diameter ratio tentative classification of growth performance into good, fair and poor growth classes is made. Below are some growth data taken from sites capable of yielding good/very good crop performances. + Eucalyptus camaldulensis and E. tereticornis; at the age of 5-7 can yield annual increments of 2.2 cm and 2.5-3.0 m in terms of diameter and height growth respectively on the average. In some very good sites, their increment in diameter can reach a record of 3.16 cm per year. + Acacia auriculiformis at the age 6-7, can yield annual increments of 1.7-2.0 cm and 2-2.4 m in terms of diameter and height growth respectively on the average under good conditions. + A. mangium, At the age 4-5 can yield annual increments of 2.8-3 cm and 2-2.5 m in term of diameter and height growth respectively. + Teak (Tectona grandis), at the age of 10 gets a mean diameter increment of 1.8 cm and a mean height increment of 1.0-1.3 m per year; at the age of 13, its annual increments in terms of diameter and height growth are 1.2 cm and 1.3 m respectively; and at the age of 16, they are 1.0 cm and 1.3 m in the order mentioned. + Pinus merkusii at the age of 14 in Ha Bac gets a mean diameter increment of 1.78 cm and a mean height increment of 0,78 m per year; at the age of 17-18 it yields a mean annual diameter increment of 1.17-1.39 cm (but in Quang Ninh the same can reach 1.54 cm) and a mean annual height increment of 0,82-0.95 m. + Pinus massoniana, at the age 17 gets a mean annual diameter increment of 1.7-1.9 cm and a mean annual height increment of 1.1 m showing better growth then P. merkusii. + Pinus caribaea, a grown in Quang Tri and Thua Thien Hue, at the age of 11-15, experiences mean annual

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increments of 1.4 cm and 0.90-1.1 m in terms of diameter and height growth respectively; at the age of 19 in Ha Tinh it can get a mean annual diameter increment of 1.14 cm and a mean annual height increment of 0.80 m. + Pinus kesiya at the age of 17 can have an annual diameter increment of 0.93 cm and an annual height increment of 0.8-0.9 m; at the age of 20- 23, its mean annual increments are 1.1-1.55 cm and 0.8-0.9 m in terms of diameter and height growth respectively. Some other timber species of interest in Vietnam such as Hopea odorata and Dipterocarpus alatus also perform very well in plantations on the right sites, with Hopea odorata at the age of 5-6 giving mean annual increments of 1.4-1.6 cm and 0.60-1.30 m in terms of diameter and height growth respectively; and Dipterocarpus alatus givng mean annual increments, at the age of 11, of 1.3-1.6 cm and 0.9-1.1 m in terms of diameter and height growth respectively. Back to contents Next>>

Page 7 of 7

Chapter 6

Development of shemes for site mapping and classification

6.1/ Introduction A site is understood as a set of specific features/factors defining the habitat of forest tree crop (s). The component factors of a site then contribute to the formation of a natural or man-made forest type and affect its production. In all cases, it is possible to find out ways and factors most appropriate to define a site. The main factors usually chosen are: climatic, topographic, parent material and soil factors. In the former Soviet Union, because of its very diverse natural conditions, there are different ways of selecting the component factors for a site. However, in practice, based on experiences encountered in plantation, stand improvement, and natural forest management, there are only two outstanding schools: that of Ukraine and that of St Petersburg. The school of Ukraine develops its site classification system to meet the needs of making investigations and doing research for forest plantation establishment and management. The two main component factors they have selected are soil fertility and soil moisture, using plants as indicators to help them assess site quality. The soil fertility/productivity is further divided into four classes, each class being related to the growth and development of a specific forest type (of pine, birch or beech...) represented by symbols such as A, B, C, D...; Soil moisture, on the other hand, is divided into six (6) classes from dry to marshy conditions and represented by digits 0, 1, 2, 3, 4, 5. Under the same climatic conditions, classes of soil fertility/productivity are matched to those of soil moisture to create site types. The school of St Petersburg develops its concepts based on studies in taiga forests. Scientists within this group select three criteria for site identification and classification; they are: soil drainage, topography and the nature of underlying parent materials, and humus type. In Vietnam, site studies have been made since 1960, using the approaches, introduced by German scientists to carry out surveys for the plantation and management of Pinus merkusii stands in Quang Ninh. Sites were classified into six (6) levels: plant life regions, plant life zones, plant life sub-zones, plant mosaics, group of site forms and site forms. More recently, Nguyen Khanh, working in the Forest Inventory and Planning Institute, has made a review of the methodologies used and tried to work out five site levels: zones, sub-zones, areas, land forms, site forms. Although there are differences in the classification systems used, the lowest level units are the same (site forms or site types). Site forms/types seem to be appropriate for use in surveys at the forest enterprise level, or in small units of production (such as a commune, a state-owned or private-owned forest enterprise) for the production of site maps of scale of 1/10,000 or 1/5,000 for the purposes of establishment of plantations or management of forests. This is also the objectives of this research activity dealing with the development of methodologies for site survey at production unit. An early technical procedure for site study and mapping was issued by the Forest Inventory and Planning Institute (FIPI) in 1984, but by now it needs some adjustments of both man-made and natural forests. The most important thing is to support technical and economic investments, using efficient and effective measures based on reliable information on sites and the species to be selected. Site studies made in Vietnam as introduced in Vietnam by German scientists are based on six (6) key factors: soil type (1), parent material (2), lie of the land (3), slope (4), soil depth (5), soil moisture (6). Thus a site form (type) is a piece of land being homogeneous (=uniform) in term of the six factors mentioned. Soil type and parent material can be found on previous works dealing with soil classification and mapping. The lie of the land described is by using the following

technical terms:hillfoot, hillside, hilltop. Slopes are divided into classes of <8o, 8-15o, 16-25o, 25-45o, >45o and soil depths into 3 classes of: >120cm, 60-120cm, and <60cm. Soil moisture is divided into 3 classes: dry, moist and wet. A site form (type) can be represented by symbols showing

the conditions of the site factors under consideration, for instance: SpFa43 means that the site is on uniform hillside (Sp) of “feralit soil (F) developed on acid magma (a), of slope class 4, dry (3), and deep (-). Under the present setting when forestry is only its way to more intensive management, such as a sophisticated site mapping procedure with six factors being involved appears to be impracticable. Much more labor should be employed on a site unit for its mappings while forest land farming still remains simple. On the other hand, the same factors being systematically applied to all areas/zones without paying attention to any key factors seems to have restricted the methodologies from being used on larger scale. 6.2/ Concepts and Methodologies. Practical field work in a number of regions and research on similar problems lead us to the following observations: the country although not very big is endowed with diverse physical/natural conditions and with soils of all kinds. Therefore, in our work of finding factors for site form identification, it is necessary:

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1. To select the factors most appropriate for the job as required by the natural/physical conditions. A uniform approach, using a fixed number of criteria for site identification and classification everywhere will not work. For instance, uniform site mapping and classification in hilly areas, on sand dunes, on sulphated soils, and in open forests of Dipterccarps dipterocrops... cannot do well, using the same criteria.

2. To choose key factors having a strong impact on tree growth to map and classify forest sites. For example in the open forest dipterocrops, on areas with acid sulphate soils, in-land sand dunes, the key factors can be soil drainage conditions, soils being flooded and/or waterlogged in the rainy season...

3. To pay much more attention to the factors most relevant to and having strong impacts on land farming and intensive management... so to simplify the problem as much as possible.

4. To use criteria easily recognizable during field surveys (either through direct observations or otherwise), not excepting indicator plants.

6.3/ factors and criteria for site form division and classification. As presented earlier, the climatic factors are not under consideration, because most surveys are to be made in small areas in which climatic conditions do not differ. Based on the surveys made, three groups of key factors are proposed for the division and classification of site forms; they are: group of edaphic conditions, group of topographic conditions, group of soil drainage and waterlogging conditions. (Table 68).

Table 68- Groups of key factors for site form division and classification.

In our study, the factor of moisture is neglected because in small area it is very difficult to detect differences in soil moisture. On the other hand as a complex factor, soil moisture is depending on a lot of other factors and it is always changing round the year. Besides, with enough information on the local climate, the lie of the land, the properties of soil, its texture, the cover vegetation, soil moisture in a site can be easily inferred. However, soil moisture will be a useful criterion when site quality is being assessed. We also add a third factor, soil texture, to the process, because the soil group/type and the underlying parent materials can only give an overall idea of the site; parent materials are very dificult to identify under field conditions while soil texture is not so in field surveys, in particular on open lands and denuded hill sides; different textural composition can be found on the same type of soil developed from the same parent materials; soil texture experiences drastic changes when the soil are severely eroded and under serious reaching of clay particles. On the other hand, soil texture has a strong impact on soil productivity, plant growth and soil cultivation. Soil drainage, and water-logging conditions, on the other hand, have a significant ecological influence in more than one area/region, in particular on acid sulfate soil, in the open forest of Dipterocarps, in the East South Vietnam, along the coasts, on in-land sand dunes... This is not to say that we have to use these factors all together everywhere for site study as shown below.

6.3.1/ Factors for site form mapping in evergreen broad-leaved natural forests.

1. Topography and lie of the land They are considered as key factors because natural forests usually occur in the mountain area, on high slopes. Attention should be given to, and mention made of: - Location: hill-foot, hillsides, hill-top. - Slopes: 4 classes: <15o, 15-25o, 25-35o, >35o. 2. Soil types and parent materials. 3. Soil depth: 3 classes: <50cm; 50-100cm; >100cm. Mention should be made of outcrops, stoniness etc. when describing soil depths-soil texture here is neglected; assessment will be made based on soil types and parent materials and of course on the key factors of topography and lie of the land.

6.3.2/ Factors for site mapping in the open forests of Dipterocarps.

Edaphic conditions Topographic condition Soil drainage and water-logging

Groups/Type of soils

Soil texture Soil depth Location Slope

Soil drainage

Water-logging

Information from soil map

and field surveys

4 classes: - Loose sand -Loamy sand -Loam -Clay

Division into classes:

depending on the objectives in hand and

field conditions

Hillfoot Hillside Hilltop

Division into classes:

depending on objectives in

hand and field

conditions

Division into:

- Good drainage -Medium drainage

-Poor drainage

-Very poor drainage

Division into classes:

Depending on objectives in

hand and field conditions

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1. Soil drainage conditions: They are key factors because waterlogging usually occurs in the open forests of dipterocarps. Division into 4 classes: - Good drainage. - Medium drainage. - Poor drainage. - Very poor drainage. 2. Topography, lie the land. Most open forests of dipterocarps on Tay Nguyen (High Plateau) are found on flat terrain conditions or easy hillsides, of low slopes. · Three topography types can be noticed in Tay Nguyen: hills and low mountains; peneplains; valleys... · Slopes: 4 classes:<8o; 8-15o; 15-25o; >25

o 3. Soil types and parent materials (rocks). When parent materials are difficult to identify, study of textural composition can be made instead, with soil texture being inventoried into three (3) classes: loamy sand, loam, clay. 4.Soil depth (not excluding the description of outcrops, concretions...) Division into 4 classes: <30cm; 30-35cm; 50-100cm; >100cm. Under field conditions there are few areas with soils of more than 100 cm deep. 6.3.3/ Factors for site mapping and classification in acid sulphate soil area 1. Water logging regime: regarded as a key factor · Depth of water logging: divided into three classes - Less than 60 cm under water - 60-100 cm under water - More than 100 cm under water · Duration under water: divided into tree classes: - Less than 1 month - 3-4 months - More than 4 months. 2. Soil types: based on soil maps available. 3. Depth of sulfate-generating layer: divided into 3 classes: - <50 cm - 50-100cm - >100cm 6.3.4. Factors for mapping sites of commercial forest plantation Commercial plantations are established on large areas and good sites of moderate slopes using intensive management methods (appropriate tree crops, improved seeds, mechanized soil preparation, stand fertilization...). Therefore site mapping for that purpose must be carefully made based on the following factors. 1. Topography and lie of the land - Location: + Hilltop (hilltop forms). + Hillside (hillside form). + Hillfoot (hillfoot form). - Slope: divided into four classes:

+ <8o

+ 8-15o

+15-25o

+ >25o

2. Soil type and parent materials: Based on existing soil maps and documents 3. Soil depth: divided into four classes - < 30 cm - 30-50 cm

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- 50-100 cm - >100cm. (Parallel with description of stoniness, outcrops hindering soil cultivation) 4. Soil texture: divided into four classes. · Sand and loamy sand (or sandy soil). · Loam · Loamy · Clay 5. Indicator plants: Emphasis should be laid upon the use of indicator plants (grasses, shrubs, bamboos etc.) so to map the sites for the purpose on mountain and hillsides, land with acid sulphate soils. Under field conditions, the approach proves to be very effective. Back to contents Next>>

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Assessment of productivity of forest land in Vietnam.

Abstract. In this book the methodologies and research results on forest land capability and suitability evaluation for the whole country of Vietnam are mentioned. Research works are carried out in 8 forestry economic zones (Northwestern, North Center, North Eastern, North Coastal, South Coastal, High plateaux, South Eastern, Mekong Delta) wid 4 different forest land groups: Land on feralit soils (Ferralsols) on hilly and mountainous area. Land on coastal sandy soils (Arenosols). Land on Mangrove Saline soils (Gleyi Salic fluvisols). Land on Acid Sulphate soils (Thionic Fluvisols). Each group has different Criteria and norms for evaluation. Four Criteria for forest land capability evaluation on hill and mountain are chosen: land slope, soil depth, soil texture and content of organic matter on soil surface. Other criteria such as soil types, land forms, wide drainage soil, distance to the sea... are identified for coastal sandy land capability evaluation. Concerning evaluation of land on mangrove saline soils and acid sulphate soils the main chosen criteria are as follows: soil types, soil texture, content of organic matter, the duration and the depth of water submergence.... Land suitability evaluation based on climatic (Annual mean temperature, lowest mean temperature, highest mean temperature, Annual rainfall..) and edaphic factors (soil types or groups, elevation, slope, soil depth) for maintree species: E. Camaldulensis, Pirus Mekusii, P. Caribeae, Acacia Manjium, A. Auriculiformis, Tectona Grandis was studied. Research results on forest land evaluation and direction of land use are presented in details in this publication. Back to contents Next>>

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Conclusion and Today Forest Land Use Problems

in Each Region. 1. An Overall Assessment of Forest Land Productivity.` Considering that forest land of grades land 2 are of very good/good productivity with no and minor limitations to forest land use, nation-wide the chain of down going forest land productivity, in which each region is given with its own forest land area of grades land 2 (in percent), can be pictured as follows (Table 69): The North Central Region (1) > The Eastern South Vietnam (2) > 82.5%) (67%) Tay Nguyen (3) > The Coastal North Central Vietnam (4) > (42%) (39.2%) The Coastal South Central Vietnam (5) > The North West (6) > (31.4%) (19.5%) The North East (7) (15.5%) * On the other hand, taking into account that forest land of grade 4 is of poor productivity and presenting a number of limitations more or less difficult to overcome, another picture showing out difficulties to be encountered can be described as follows: -There are three regions in which the area of forest land of grade 4 is of some importance; they are: the Coastal South Central Vietnam, where it amounts to 430;0, then come the North West and the North East where it extends over almost the same percentage of 1 7% of their own total forest land area. -Other regions have a smaller area of forest land of grade 4, in particular Tay Nguyen High Plateaux, the Eastern South Vietnam and the North Central Region. * Forested areas on land of grade 1 and 2 are distributed as follows: 59% in the Eastern South Vietnam, 43% in the North Central Region, 34% in Tay Nguyen High Plateaux, and 22% in the Coastal North Central Vietnam. In other remaining regions, forested areas on land of this quality account for a lower percentage. * Non-forested ~reas are found on forest land of grades 3 and 4, mainly grade 3. For Instance non-forested areas on forest land of grade 3 are distributed with a percentage of 52% of forest land total in the North West; in other regions: the North East, the Coastal North Central Vietnam, Tay Nguyen High Plateaux, they amount to smaller percentages. Non-forested areas on forest land of grade 4 can be found in the Coastal South Central Vietnam where it .extends over 19.3%, then in the North West where it covers over 14% of the regional forest land area there. Non-forested areas on forest land of grade 2 can be found only in restricted areas, but in the North Central Region they occur on almost 40% of the total. As a recapitulation on a regional basis, the following can be said: * Out of the region under study, the three regions of: North Central, Eastern South Vietnam, and Tay Nguyen High Plateaux are ranking in the first group because: -The North Central region has the highest percentage of its forest land of grades 1 and 2 in the country; the soils there are deep, well provided with organic matter and mainly of loamy texture, and non-forested areas on land of grade 2 cover extensive areas; limitations mainly (~ome from high slopes but not exceeding those found in many other areas where forestry has been developed for ages. -The Eastern South Vietnam, on the other hand, is well known for its low slopes, its soil depths within reasonable range, half of its forested areas on land of grade 2, its extensive area of grey soils, and its high water table from which enough water can be taken up for tree crop cultivation and management. -Tay Nguyen is famous with its "fertile" soils, but when taking into consideration all the four factors used for assessment as mentioned earlier, it only ranks third after the North Central Region and the Eastern South Vietnam. Forested areas on Tay Nguyen High Plateaux are found on land of grades 2 and 3 with almost the same percentage, 33 and 39% respectively. Non-forested areas there are on land of grade 3 (18.4%). With its specific climatic conditions, its fertile basaltic soils, Tay Nguyen is endowed with evergreen broad- leaved forests of high productivity (reaching a standing stock volume of 500 cu.m/ha), with big- sized timber trees (most of them above 60 cm Dbh at maturity), with extensive forests of Pinus kesiya. (vernacular Thong ba la) providing high yield of about 10-12 cu.m /ha/a, all of which pointing to the high productivity of its forest land. But it is also worth mentioning here that the open forests of Dipterocarps, although occurring in very flat areas, are not so ecLsy in successful management. Relating to degraded basaltic soils, the plantation of fast-growing tree species is not something easy to achieve. * Coastal North Central Vietnam (commonly known as the Former 4th zone) when compared to Tay

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Nguyen gets almost the same pattern of forest land distribution in terms of its land of grades 2 and 3, its forested and non-forested areas. But some slightly more favourable ditions can be found on Tay Nguyen, which makes the Coastal North central Vietnam rank after Tay Nguyen, in the second group. * North West because of its high land slopes, its low vegetation cover, strong soil erosion and rather dry conditions is thought of as being unfavourable to forest plantation establishment and management. But, m taking into account of its soil depths, it high contents of surface organic matter, one can find that land productivity in the Region [lot be rated as very low, because among many other things there there some productive soils developed on calcareous alkaline magma materials... and containing high amount of humus. As a result, the North West should be ranked above the Coastal South Central Vietnam and even the North East. * North East as a whole cannot be rated as a region favourable to forestry development, because of its extc3nsive forest land area "with high slopes (80%), its shallow soils of poor organic matter. However, when comparison is made with the Coastal South Central Vietnam, one can find that forest land of grade 4 in the North East accounts for a smaller percentage than the same in the Coastal South Central Vietnam, which because of its lower land productivity and a higher degree of diffculty encountered in land use should be ranked at the bottom of the list. * Mekong Delta with all its particulars has been assessed quite separately, because of its problems with mangrove saline and acid suIphate soils. However, under the present state of technology and forest tree cropping, the information collected points to the fact that half the forest land in the Region is suitable for the cultivation of forest crop, capable of yielding reasonable outputs without serious limitations; the other half may require higher capital investments when used. On the other hand, some combined fishery-forestry models have been established there following careful land evaluation showing that sustainable production of wood and sea products can be secured using integrated land farming systems. 2. Problems :Facing Forest Land Use. The above-mentioned findings help us point out the following recommendations to solve problems facing forest land use. 1. Efforts should be made to enhance the productivity of forest land in all regions where conditions are most favourable, i.e. first of all in the North Central Region, the Eastern South Vietnam, Tay Nguyen High Plateaux, then the Coastal North Central Vietnam (or the Former 4th zone) . 2. For forested areas, mainly endowed with productive forests on land of grades 1 and 2 in the Eastern South Vietnam, the North Central Region and Tay Nguyen, it is vital to design efficient/effective methods and measures for intensive management enhancing the existing timber and other forest product yield and production. 3. Non-forested areas on land of this quality (grades 1 and 2) are found in the North Central Region in extensive areas. It is necessary to develop and carry out intensive management of well established j.ndustrial and commercial plantations. Other non-forested areas on land of grades 3, and in particular those in the Coastal South Central Vietnam on land of grade 4, may require more inputs for improved management. 4. Forest land with high slopes (over 35°) is found mainly in the North West and the North East where it occurs over 73-860/0 of the regional total. The coping strategy is to create systems of protection forests capable of yielding some forest products, because nearly 60% of non-forested areas there still demain denuded. A next step is to develop,the same strategy in the Coastal South Central Vietnam and also in the North Central Region. 5 Once again, the regions endowed with favourable conditions for natural and man-made forest management (low slopes of classes 1 and 2, with only parts of the land under slope class 3, soil depths ranging from 50- 100 cm to above 100 cm; soil organic matter contents of classes 1 and 2) are: the Eastern South Vietnam, the North Central Region, Tay Nguyen and perhaps the Coastal North Central Vietnam (or the Former 4th zone). 6. A new assessment of the land productivity in the North West should prevail. So far such favourable conditions as deep soils, high humus contents of the Region have not been received adequate consideration for forest land use and management there. 7. Sandy soils as a rule are not favourable for forest land use, because of their low natural productivity, but there exist in the Regions they Occur a number of productive models for further study and experimentation. Moreover, problems of in-land sand gley far away from the seashore, of impeded drainage and peaty sand should be studied to remove land use limitations in the areas they occur. 8.For forestry development in the Mekong Delta, the urgent thing to tackle is to take advantage of what is favourable there (i.e. nearly half of its total forest land area can be used to support plantations to restore mangrove forests and the natural vegetation cover on acid sulphate soils). The other half

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will be dealt with step by step through adequate and timely investments. On the other hand, some productive models of integrated forestry-fishery farming have been established there so to encourage to re-establishment of Rhjzophopa spp. forests and the plantation of Melaleuca sp (leuca.dendpon and Cajupyty) on saline and acid sulphate soils. 9. Referring to the "basket" of forest tree crops now in use, one can say that besides the indigenous tree species, attentioI) should be paid to the use of some promising exotics such as Acacja aupjculifopmjs and A.mangium, and their hybrid the success of which in plantations appears to be secured and of some species and provenances of eucalypts such as Eucalyptus UPOPhylla., E. tepetjcopms and others that can be grown at higher elevations in the mountainsn (E. Saliqua, E. mjcpocopjsv.). On the other hand, pjnus capjbaea. seems to get adapted to the conditions of the Coastal regions of Central Vietnam and Tay Nguyen. And the development of Teak plantations seems to be viable in the Eastern South Vietnam and Tay Nguyen. Edaphic factors strongly have impacted on growth of commercial planted forests. These factors in lot of plantation area are low suitable so that yield of planted forests also is not so high. It is time to mention here that pure-stand plantations (or monocultured of e crops) should be avoided as much as possible, because pests and deases appear to have occurred in pure plantations of 10 years of age of timber species not excluding those planted with indigenous species such Hopea. odopata (vernacular Sao) and Diptepocappus alatus (vernacular dau rai) , 10. To enhance the productivity of forest land in all regions under study, it is necessary: -To make adequate and well balanced investments; -To develop strategies for intensive management of natural and man- made forests, to strengthen the forest protection systems and not the least to develop facilities for better plant breeding for the production of improved seeds and seedlings; -To develop technologies for sloping land farming, agroforestry extension with a consistent view to usher in efficient but sustainable land use. -To develop master plans for strengthening the relationships between: Agriculture, Forestry and Fishery for the creation of effective integrated farming systems wherever and whenever they are necessary and urgent for both economic development and environmental conservation. -To create much more facilities for the study of forest product outlets and markets, because there are indications now that production of fruit products and non-wood forest products... in the mountains have come a standstill for want of ready markets. Back to contents Finished>>

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