Ghana Journal of Forestry Vol. 3 1996

REQUIREMENTS FOR AND FACTORS AFFECTING BIODIVERSITY:A WEST AFRICAN PERSPECTIVE

A. B. OGUNTALA

FORESTRY RESEARCH INSTITUTE OF NIGERIA, JERICHO, IBADAN. NIGERIA

ABSTRACT

In West Africa, due to over-exploitation of natural resources there is threat of loss of biodiversity. Biodiversity is

a matter of survival as it is the source offood, fuel, medicines, housing materials and economic security.

Ecological principles necessary for the management of biodiversity must be clearly understood before they canbe applied. Critical species, habitats and ecosystems exist throughout the West African landscape ranging from

parks, pasture lands, forest reserves to fallow fields. Much of West Africa's biodiversity exists outside theprotected area system and they require urgent protection. Improvement in resource management needs to beapplied across the full spectrum of eco:"ystems and habitats within each country.

A multi-disciplinary approach is needed in the development and implementation of strategirs for themanagement, conservation and utilization of biodiversity resources on a sustainable basis. More research is

however needed and very urgently too in the taxonomy, ecology and utilization of West Africa's biologicalresources, before they become extinct.

Key words: Biodiversity, exploitation, conservation,utilization research.

INTRODUCTION

Biological diversity must be treated seriously asa global resource, be indexed, used and aboveall preserved. Three circumstances make itimperative for this to be given an unprecedentedurgency, particularly in West Africa. Firstly,exploding human populations are degrading theenvironment at an accelerating rate in the sub­region. Secondly, science is discovering newuses for biological diversity in ways that relieveboth human suffering and environmentaldestruction. Thirdly, much of the diversity isbeing irreversibly lost through extinction causedby the destruction of natural habitats, which isoccurring more in Mrica than elsewhere(Wilson, 1988).

Biodiversity is a vital resource because it is thegateway to better and faster supplies of matterand energy to humans (Lal, 1991).Unfortunately plant biodiversity survey, docu­mentation and conservation activities are not

keeping pace with this rate of forest exploitationand destruction in West Africa. The pressure on

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land as well as the impact of the land-usepatterns have led to the destruction and erosionof many valuable plant germplasms that are ofcurrent and future potential importance.

Most urgent attention is however needed on thetropical moist forest ecosystems because, of ailthe major habitats, they are richest in speciesand are in greatest danger of destruction(Wilson, 1988). The fundamental problem ofloss of biodiversity in West Africa may haveless to do with the amount of land under

protection than with the forms of land-usetaking place on the remaining portions of thelandscape which in most cases represent farlarger areas than those classified as protected.

In Africa., about two-thirds of the land that couldsupport habitats for wild plants and animals isnow used for other purposes (Mackinnon andMackinnon, 1986). Nevertheless, Africa stillcontains a wealth of biodiversity. Whereas incertain parts of the world it may be too late to

Ghana Journal of Forestry Vol. 3 1996

stem the loss of much of the biodiversity thatformerly existed, in most of Africa (West Africainclusive) the opportunity still exists forproactive intervention (Biodiversity SupportProgramme, 1993).

Efforts to protect the natural environment musthave a holistic approach in West Africa andelsewhere. New strategies for conservingbiodiversity in West Africa are urgently neededthat:

- respect and incorporate African values,knowledge, systems and priorities;

- involve the local people in the managementand use of biological resources;

- can control or reverse the loss of biodiversityin every country in the region; and

- treat biodiversity conservation and economicdevelopment as integral aspects of the sameprocess of sustainable development.

In this paper, an attempt is made to focus on therequirements for the conservation, managementand utilization of biodiversity resources in WestAfrica on a sustainable basis.

Requirements for Biodiversity

The ecological principles relating to biodiversityhave to be understood before they can beapplied effectively particularly in the manage­ment of forest resources. The fundamental

principles related to biodiversity according toLal (1991) are:

• ll1e greater the diversity of an ecosystem, themore stable it is in terms of resilience to the

human impact. The West African forestrypractices which in the past gave preferredtreatment to some selected so-called

economic species at the expense of othersreduced the stability of the forest ecosystemsleading to their complete conversion tomonoculture plantations, which are lessstable.

• The diversity of an ecosystem increases as a

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function of time during succession from aninitial state where it had a minimum value toone where it has maximUl11, when the

ecosystem is called a climax community. Inthe Nigerian or West African context itshould be kept in mind that most of thenatural forests are not climax, but seralcommunities which have been continuouslydisturbed by hUl11an activities. Climaxforests are now rare in West Mrica. If human

interference in these ecosystems is stoppedor controlled, the ecosystems will evolvetowards more species diversity, while in theprocess their immediate economic value willdecrease because conservation activities

reduce economic gains in the short run.

• The biomass/productivity ratio of anecosystem is proportional to its biodiversity.Man-made forests or disturbed natural

forests though poor in species are moreproductive than undisturbed natural forests.Productivity of environment, nevertheless, isas in1portant as its stability. Monoculturesare however fragile and susceptible toenvironmental disturbances. It is therefore

necessary that natural forests with highbiodiversity values should serve as geneticpools after careful studies. DestructivehUl11anintervention should be excluded from

such forests ego Strict Nature Reserves orWorld Biosphere Reserves.

• Species diversity is dependent on thestability of the environment. Communitieswhich evolve in stable environmentalconditions or which have suffered only

regular or foreseeable fluctuations show themaximum species diversities because of theinfluence of the nearby undisturbed forests.

• Ecosystems rich in diversity exploitecosystems poor in diversity. In other words,mature, climax communities remove matterand energy from in1mature communities. Forexample, mature forests attract epiphyteslike orchids, wildlife and other rare species.They also store water and nutrients removedfrom more disturbed areas.

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Maintaining Structural and FunctionalDiversity

Preserving biodiversity in West Africancountries and in other countries requires themaintenance of all successional stages. Sinceearly successional stages are typically wellrepresented, a major concern is preserving or re­creating the mature forest. Such mature foreststypically contrast with early successional stagesin composition, structure and function.

Due to human pressure, most West Mricanforests are disturbed forests that have developedafter logging or silvicultural treatments; thecomposition and structure of these forests havechanged in comparison with the original forests.The mahogany dominated forests of SapobaForest Reserve, for instance, in Edo State ofNigeria have changed to other speciespreviously regarded as uneconomic.

FW1ctional differences between mature and

young forests are often qualitative rather thanquantitative. That is, forests at all stages fix andcycle energy or carbon, regulate hydrologicflows and conserve nutrients. Mature forests

present a very large crown surface and occupyan extensive volume of space, because dominanttrees in West Mrica are commonly taller than50m. Such forests are particularly effective atgleaning moisture from clouds and fog, whichcan substantially increase precipitation (Harr,1982). In addition, the mature forests provideseveral important sites for nitrogen fixation (eg.epiphytic lichens) and decomposing wood,which are more limited or absent in earlier

stages of succession. Mature forests and theorganisms and processes that they represent arean essential aspect of global biodiversity at risk.Thus preserving or re-creating mature forestsshould be a key objective of any conservationprogrme. Such efforts would be timely inWest Africa since there are still opportunities toretain some mature forest ecosystems and toallow younger forests includrng man-madeplantations to develop into mature naturalforests.

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Rate of Change in Tropical Forest Areas

The rate of change in tropical forests of all kindshas been discussed in depth by Lanly (1982)who made an effort to document the rate ofincrease in the area of secondary forests (byreforestation, afforestation and naturalregeneration) as well as of the rate of forestsloss. Other attempts usually emphasizeconversion or modification of mature forests

with little or no analysis of recovery (Myers,1980). Lanly (1982) showed that of the 11.3million ha of mature tropical forest landdeforested annually, 5.1 million ha are convertedto secondary forest fallow. He estimated that thetotal area of this forest type is 409 million haand almost one million hectares of secondaryforest is created annually on unforested landthrough natural regeneration or humanintervention (Lugo, 1988). Such large forestareas cannot be dismissed as irrelevant to the

conservation of species diversity because theysupport extensive biota and because undercertain conditions they are capable of supportingmore complex biota than the mature system theyreplace (Ewel, 1983). Lanly (1982) also showedthat deforestation rates are higher in closed thanin open forests. Within closed forests a largefraction of the conversion involves loggedforests that have previously been modified byhuman activity. Moreover, recovering secondaryforests are potential foster ecosystems forendangered species and their role in speciesconservation must be considered.

The Extent of Deforestation in Africa

Out of the total land area of Africa constituting

2,236 million ha only 568 million ha wascovered with forest in 1980. In 1990 only 527million ha of forests were left, representing anannual change within ten years of 4.1 million haor - 0.7 percent annual rate of change.Comparative annual rate of change (ie.deforestation) in Latin America was - 7.4 andAsia - 3.9 million ha (FAO, 1993).

The tropical rainforest of Africa occupies 118.5million ha., compared with Asia 306 and LatinAmerica 522.6 million ha. Deforestation is also

continuing in the dry and very dry zones.

Ghana Journal of Forestry Vol. 3 1996

According to the FAO (1993), the total landarea of this zone is 823.1 million ha, with aforest cover of 151.2 million ha or 18% of thezone. Annual deforestation rate in the zone is1.1 million ha or 0.7%.

The total amount of operable productive forestsin Mrica (FAO, 1993) was 169.2 million ha,unfortunately only 2.0% of these forests wereput under an organised management system.The remaining forests have no working orexploitation plans. Uncontrolled exploitationboth legally and illegally have reduced theforests to derelict forests. Studies of the growingstock of productive forests in some selectedMrican countries was carried out by FAO in1984. Table 1 shows the estimated, current andprojected values of growing stock in someselected countries including Nigeria. ThreeAfrican countries, Cote d'l voire, Nigeria andSenegal may have nothing left in their closedproductive forests, by the end of the century.Skoup (1986) reported that Nigeria has beenlosing on the average about 23,000 ha ofgazetted forest estate per annum throughGovernment dereservation alone.

Over 350,000 ha of forests and savanna

woodlands are estimated to be destroyed eachyear through clearance for farming, uncontrolledfires, or conversion to some other forms of land

use, (World Resources Institute, 1987). Thecumulative effect of all these is that in Nigeria,which in 1897 had 60 million ha of forests and

woodlands, now has only rougWy 9.6 million haof forest reserves, much of which is degradedand only 2.4 million ha are in the forest zone - aloss of over 50 million ha in less than 100 years.Between 1981 and 1985 closed forests were

being converted at the rate of 5 percent per3lmunl in Nigeria (World Resources Institute,1987).

Causes of Deforestation

There are several agents of deforestation inMrica and Nigeria in particular. The maincauses of deforestation are population growthand the expansion of economic activitiesincluding logging or timber extraction, farming,urbanisation, bush burning, firewood collection,

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Table 1: Estimated growing stock in selectedclosed productive African forest (million m3).

Country 198019902000Variation1980-2000

Angola

270222173(97)

Ghana

198165132(66)

Guinea Bissau

25168(17)

Cote d'lvoire

766990(766)

Liberia

22014570(150)

Nigeria

492440(492)

Senegal

200(2)

Cameroon

4,6454,4344,223(422)

Central Mricar

1,1021,0861,070(32)Republic

Source: Outlook for the Forestry Sector inAfrica, FAO, 1984.

grazing and infrastructural development (NEST,1991; FAO, 1993). During the oil-boom yearsof the 1970s in Nigeria there was a massiveincrease in construction activity whichheightened the demand for timber. Most of thetimber came from the high forest, inside andoutside the forest reserves. There was a

breakdown in the regulation of logging activitiesin these areas. Consequently the country'sstanding crop of valuable species has beenseverely depleted and in some cases havebecome endangered. Outside constituted forestreserves, the main deforestation agent is thefarmer. Over 75% of the total forest area cleared

yearly is by these farmers (NEST, 1993). Thetendency is for farmers to encroach on forestreserves where the soils are relatively morefertile. More recently multinational companieshave also joined the forest clearing bandwagonin the drive to derive raw materials locally andincrease food production.

Bush buming is another notorious agent ofdeforestation in Nigeria and West Africa. Theburning is done by farmers who use it for land

Ghana Journal of Forestry Vol. 3 1996

clearing, herdsmen who use it to regenerategrass, hunters to kill wildlife and some villagersto clear their surroundings (NEST, 1991).

Over-exploitation for firewood as well asovergrazing is a major cause of deforestation inthe savanna. Clearfelling of trees for commercialfirewood without any thought of regeneration isa common practice in many African countries.The rocky hill slopes are not spared.Overgrazing is a serious problem in the Sudano­Sahel where overstocking around wateringpoints often results in serious damage tovegetation.

Conservation and Biodiversity Issues

There are a number of common issues which

have bearing on the preparation of anybiodiversity conservation Strategy Plan (ODA,1991):

• There must be a common agreement in whatis valuable. An ethnobotanical survey needsto be carried out in which the views andcultural values of the local inhabitants are

incorporated. It is not the views ofGovernment officials alone that determine

the value of biodiversity.

• It is important to recognise the fact thatbiodiversity objectives will vary according tovarious communities for whom the forests in

their locality have become their heritage. Forinstance, the values placed on the forests inOmo Forest Reserve in Ogun State aredifferent from those of Taylor Creek ForestReserve in Rivers State of Nigeria or fromthose of Ehor Forest Reserve in Edo State.

Deforestation is quite rampant in OmoForest Reserve compared to the other tworeserves, where there are more conservationefforts.

• The objectives of biodiversity conservationmust be precise to be useful. For example,the objective "to maintain as much diversityas possible" is very vague and unhelpful toforest managers. A precise definition ofgoals and measure ofbiodiversity needs to

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be set for the management of each forestreserve. Depending on the speciescomposition and structure of the forests, theemphasis may be on shrubs, climbers orherbs rather than on trees.

The wider objective of any biodiversityprogramme is to maximize the conservation anduse of biodiversity in order to providesustainable, social and economic benefits to thegenerality of the people. For example, the mostdeserving habitat or forest reserve in onecountry might have a very low global priority.The reverse is also true. For instance theconversion of the Strict Nature Reserve in Omo

Forest Reserve, Nigeria, into a World BiosphereReserve has saved the most mature forest in

Ogun State from destruction. Various adjacentplots have been seriously tampered with.

CONCLUSION

Species richness can be partially restored tolands previously used heavily for agriculture.Growing timber need not eliminate all naturalrichness on the site. Tropical lands respond tosensible care through management. Theobstacles are social and rooted in poor trainingand education programmes, lack of commitmentto forestry research and to enforcement ofregulations and the absence of a landconservation ethic, because economicconsiderations far outweigh environmentalissues. A strategy for forest and speciesconservation in tropical regions should focus onthe restoration of forest production on fonnerforest lands where food production is notsustainable. The weak forestry institutions alsoneed strengthening. Sensible use of secondaryforests and tree plantations will reduce pressureon forest lands with mature forests or with

unique ecological characteristics and set us on acourse to meet the needs of the needy whileprotecting species diversity.

Ghana Journal of Forestry Vol. 3 1996

REFERENCES

BSP (1993). African Biodiversity: Foundationfor the future. A framework for integratingbiodiversity conservation and sustainabledevelopment Biodiversity Program Support.Maryland USA p. 149.

Ewel, J.J. (1983). Succession. In F.B.Golley,ed. Tropical Rainforest Ecosystems. Structureand Function ..Elsevier, Amsterdam. p. 217-223

FAO (1984). Outlook of the Forestry Sector inAfrica. FAO, Rome.

FAO (1993). The challenge of sustainableforest management: what future for the world'sforests? FAO, Rome p. 128.

Harr, R.D. (1982). Fog drip in the Bull RunMunicipal Watershed. Oregon Water ResourcesBull. 18(5): 785-789.

Lal, J.B. (1991). Conservation and sustainablemanagement of forest ecosystems as geneticresource. 10th World Forestry Congress. 2:521-529.

Lanly, J.P. (1982). Tropical Forest Resources.

FAO Forestry Paper 30, FAO, Rome. p. 106.

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Lugo, A.E. (1988). Estimating Reductions inthe Biodiversity of Tropical Forest Species In:Biodiversity. E.O. Wilson Ed. p. 58-70.

Mackinnon, J. and Mackinnon, K. (1986).Review of the protected areas system in theAgrotropical realm, IUCN Gland Switzerland.

Myers, N. (1980). Conversion of moist tropicalforests. National Academy of Sciences,Washington D.C. p. 205.

NEST (1991). Nigeria's threatenedenvironment: A National Profile NigerianStudy/Action Team p. 288.

ODA (1991). Biological Diversity andDeveloping Countries: Issues and Options.Overseas Development Administration p. 50.

Skoup (1986). Feasibility Studies for NationalForest Resources Survey. Fed. Dept. ofForestry. Ibadan.

Wilson, E.O. (1988). The Current State ofBiological Diversity. National Academy Press p.521.

World Resources Institute (1987). World'Resources' New York basic Books.