Zbigniew KLIMOWICZ Stanisław UZIAK Department of Soil Science Institute of Earth Sciences Maria Curie-Skłodowska University Akademicka 19 20-033 Lublin, POLAND

Wyprawy Geograficzne na Spitsbergen UMCS, Lublin, 1994

PRELIMINARY EVALUATION OF EXPOSURE EFFECT ON THE SOIL COVER STUDIED ON THE SLOPES IN DYRSTAD AND TJ0RN VALLEYS (WEST SPITSBERGEN) AS THE EXAMPLE

INTRODUCTION

Relief is one of the most important factors influencing the soil cover. It has been widely discussed, particulary, with regard to the well developed con-figuration of the terrain by Polish and foreign authors. Configuration can accelerate or delay the action of climatic factors. It not only modifies climatic effects but can be a predominant factor in some cases e.g. in the mountains. As for Arctic soils E. A. FitzPatrick believes that there is an evident relationship between the slope character and surface forms of soils found on this slope.

There are few detailed reports in literature about the effect of exposure as an element of relief on soil cover character. Some general remarks, among others, in books mainly refer to different conditions on the slopes of northern and southern exposures. For example, the soils on the slopes of southern exposure undergo stronger insolation and as a result quicker and stronger drying up which can affect the course of soil processes.

The aim of this paper is to study the effect of exposure on soil character in the Arctic tundra zone.

STUDY AREA A N D METHODS

Character of valleys including their slopes was studied both in Bellsund and Isfjord regions - the two biggest fiords in the western part of Spitsbergen. Different soil-vegetation conditions were easily noticeable in this area. Some slopes were almost devoid of vegetation and soil while others were densely covered with vegetation eg. in Gronfjord (the branch of Isfjord).

The slopes of Bellsund southern border, from Lognedalen in the west to

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Chamberlindalen in the east were subjected to detailed studies. In this area two representative slopes of contrasting exposures: WSW-ENE were chosen. The slope of WSW exposure borders Dyrstaddalen in the east but the slope on the opposite side is a part of Tjorn Valley. It should be emphasized that the mentioned exposure of slopes is predominant in the study area as the mountain ridges have a position close to a meridional one. Two levelling soil sections, one up to the largest decline of the slope and the other transverse to it at the foot of the slope were made on the slope and at its foot in Dyrstad Valley (Fig. 1). It enabled better spatial evaluation of soil and vegetation cover distribution. One levelling - soil section running across the slope and its foot was made in Tjorn Valley.

In several dozen sites soil morphology was studied and character of vegetation cover was determined specifying the predominant species. Soil samples for laboratory analyses were taken up from some profiles. Granulometric com-position and basic chemical properties were determined to make general evaluation of the studied soils possible.

RESULTS

Occurrence of a soil-vegetation cover in the area of Bellsund southern border is clearly asymmetric which referes particularly to the large valleys: Lognedalen, Dyrstaddalen, Tjorndalen and Chamberlindalen. In these valleys the slopes of western exposure are privileged with respect to soil. They are accompanied by a dense vegetation cover sometimes reaching 100%. On the contrary, the slopes of eastern exposure are often devoid of soil being sometimes bare and severe in their look.

The above mentioned regularities are not so distinct in the case of short but wide Blomlidalen and Bohlinryggen slopes, the ridge pushed between the two glaciers: Scott and Renard.

The slope of WSW exposure (Section I) is covered with vegetation up to half the distance from the glaciers in the Dyrstad Valley. The density of the vegetation cover can be estimated as about 15 to 80 and even 100%. It reaches the peaks of the ridge. Only very few scree taluses occuring here are without vegetation. The surface studied on this slope (Fig. 2). has a 100% soil-vegetation cover. Shallow and very shallow mineral-organic soils developed on the light and medium silty loam (Tab. 1). However, thickness of organic horizon is large taking into account arctic conditions. The degree of organic matter decomposition is low and its content oscilates from about 20 to 72%. It should be added that in the case of biomass - its slow increment and decomposition under the arctic climate conditions were discussed in the papers prepared in the Department of Soil Science, Maria Curie-Skłodowska University, Lublin. According to Z. Fischer

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(1990) a low level of organic matter decomposition under the polar climate conditions can be explained not only by thermal conditons but also by their joint action with unfavourable water conditions. The soils in the study area have neutral and alkaline reactions. According to FAO classification they possess the features of both regosols and histosols. In the upper part of the slope they can transform into lithosols but in the valley bottom into gley soils and in the case of lighter formations into brown soils (according to FAO - Cambisols).

In the upper part of the section moses are predominant and the vascular plants such as: Sal ix polaris, Saxifraga hir cuius, Saxifraga caespitosa are frequently found. In the lower part close to the slope bend, exuberant and beautiful mosses appear. With the decrease of slope decline, more or less in the half of section more grasses as well as Cardamine nymani - a plant of characteristic small, round leaves rarely found at least in the central part of Bellsund southern border are observed. This plant is sometimes accompanied by Saxifraga cernua.

The conditions on the slope of ENE exposure in the Tjorndalen are quite different i. e. they are more severe (Section II). Fragmentary vegetation is found mainly close to the valley mouth. There is no vegetation and soil close to the glacier.

The above mentioned section (Fig. 3). was made at the same height a. s. 1. as section I. In the upper part of section sharp decline of the slope can be seen. Material consisting of stones and bloks is here strong pushed into a rock matrix of silty clay composition. Patches of initial soil cover a small area. The vegetation: mosses, Saxifraga oppositifolia, Stereocaulon species, Saxifraga caespitosa, Salix polaris, Cerastium arcticum, grasses is rare here. There is no soil and vegetation in the distance of 10-40 m. Mostly bloks and stones pulled down from the steeper part of the slope are found here. Then to about 70 m the soil of clayay silt granulometric composition is situated in patches among boulders. It has an initial character. The plants such as mosses, Salix polaris, Saxifraga oppositiofolia, Equisetum variegalum are rare. The final part of the section shows very slight inclination of the ground which is saturated with water. The soil on which a shallow organic-mineral level formed is of clayay silt composition and occupies about 80% of the area. The most frequently found plants are: mosses, Salix polaris, Saxifraga oppositifolia, Polygonum viviparum, and grasses in large tufts in some places.

The soil in section II compared with those on the slope of Dyrstad valley (section I), possess higher pH and CaC0 3 content (tab. 1). However, the greatest differences come from organic horizon thickness and organic substance content as shown in Fig. 4. As stated before the species of plants on both slopes are also different.

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CONCLUSION

The slopes in the area of Bellsund southern border of western exposure are characterized by better climatic-vegetation conditions limiting soil cover for-mation compared with the slopes of opposite exposure. Different, better climatic conditions on the western slopes are confirmed by receded glaciers as shown in Fig. 1. Some climatic and resulting from it soil-vegetation "privilege" in the western part of Spitsbergen is undoubtedly due to the northern arm of the warm Gulf Stream which reaches Spitsbergen from the west.

REFERENCES

Gnu Dianxiang, Wei Zhengfeng and Ma Yijun, 1993: The Freezing and Frost Heave Regularities of Base Soil for Arbitrary Slope Direction and Gradient. Permafrost. VI International Conference, vol. 2, 1108-1112.

Fischer Z., 1990: The influence of humidity and temperature upon the rate of soil metabolism in the area of Hornsund (Spitsbergen). Polish Polar Research, vol. 11, 1-2, 17-24.

FitzPalrick E. A., 1980: Soils, the formation, classification and distribution. Longman. London and New York.

Klimowicz Z., Melke J., 1991: The influence of lithology and terrain relief on the soil of Calypsoslranda. Wyprawy Geograficzne na Spitsbergen, UMCS, Lublin, 135-143.

Klimowicz Z., Melke J., Uziak S., 1993: The influence of relief and lithology on soil formation in West Spitsbergen. Permafrost. VI International Conference, vol. 1, 350-355.

Melke J., Chodorowski J., Uziak S., 1990: Soil formation and soil properties in the areas of Lyellstranda, Dyrstad, and Logne in the region of Bellsund (West Spitsbergen). Polish J. Soil Sci., 22, 2, 213-222.

Pirożnikow E., Górniak A., 1992: Changes in the characteristics of the soil and vegetation during the primary succession in the marginal zone of the Werenskiold glacier, Spitsbergen. Polish Polar Research, vol. 13, 1, 19-29.

STRESZCZENIE

Na obszarze Bellsundu oraz Isfjord u badano charakter dolin, w tym ich zboczy w aspekcie pokrycia glebowo-roślinnego. Wstępną ocenę wpływu ekspozycji na pokrywę glebową przep-rowadzono na przykładzie stoków w dolinach Dyrstad i Tjorn (południowe obrzeże Bellsundu). W kilkudziesięciu punktach zbadano morfologię gleb a także określono charakter pokrycia roślinnego z podaniem gatunków dominujących. Z niektórych profili pobrano próbki glebowe do analiz laboratoryjnych. Zbocza na obszarze południowego obrzeża Bellsundu o ekspozycji zachodniej (na omawianym terenie dominują zbocza o ekspozycjach wschodniej i zachodniej) cechują się w porównaniu ze zboczami o wystawie wschodniej wyraźnie korzystniejszymi warunkami klimatyczno-roślinnymi, limitującymi tworzenie pokrywy glebowej. Różnicę największą w badanych właściwościach gleb stanowią: miąższość poziomu organicznego i zawartość substancji organicznej. Ponadto skład gatunkowy roślin na obydwu stokach jest nieco odmienny. Do tekstu załączono 4 ryciny i 1 tabelkę.

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Tab. 1. Granulometric composition and some chemical properties of the soil studied (1993)

Pro-file No .

Hori-zon

Depth Colourx/

Grain size content /%/ pH CaC03 Org. mat. / * /

С Pro-file No .

Hori-zon /em/ Colourx/

1-0.1 0.1-0.05

0.05-0.02

0.02-0.005

0.005-0.002 0

< .002 2 0.1-0.02

E

<0.02

/КС1/ /%/ Org. mat. / * / /%/

W ff S, Exposure 3 0 1-7 5 YR 4/6 nd nd nd nd nd nd - - 7.1 0.6 72.0 -

AD 10-20 10 YR 6/3 39 15 22 17 4 3 37 24 7.8 5.8 - 1.54

6 0 2-8 10 YR 5/2 nd nd nd nd nd nd _ _ 6.6 3.2 22.1 _ 0 12-18 10 YR 5/3 nd nd nd nd nd nd - - 6.5 0.7 17.7 -

0 22-28 nd nd nd nd nd nd nd - - nd nd nd nd

9 D 13-18 10 YR 6/3 24 22 18 22 7 7 40 36 7.7 1.1 - 1.11

E E N Exposure 13 AC 1-4 2.5 Y 6/2 0 3 32 49 15 1 35 65 7.6 10.3 - 3.36

21 A 0-4 10 YR 6/2 nd nd nd nd nd nd _ _ 7.4 4.7 11.1 _ AD 10-20 10 YR 7/2 0 9 37 41 12 1 46 54 7.8 10.8 - 2.04

x / after Standard Soil Colour Charts /by M. Ovama, H. Takehara, 1967/

- v i i ©3

Fig. 1. Location of study area in Bellsund region. 1 - mountain ridges, 2-glaciers, 3 - cross-sections 0,11)

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Fig. 2. Dyrstad section I (A-B). 1 - topographic section, 2-geological section, 3 -pedological section; 1-11 - soil pits, a - mineral-organic material, b - light or medium silty loam, с - organic horizon O, d - underlying material D, M O s. - mineral-organic soil, shallow, MO v.s. -mineral-organic soil, very shallow

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Fig.3 .Tj0rn-sect ionII (А-В). 1 - topographicsection,2-geological section,3-pedological section; 12-24 - soil pits, a - mineral-organic material, b - silly clay or clayey silt, с - humus horizon A, d - transitional horizon AC, e - transitional horizon AD, f - parent rock C, g - underlying material D, MO v. s. - mineral-organic soil very shallow, I - Initial soil, L - lack of soil cover

* * * a b < 1

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W S W Depth Ю # of org. of

horizon , org. mat. cm

20

0 I ENE

( lack of

org. hor izon)

s lope foot of a s lope s l o p e toot of a s l o p e

Fig. 4. Influence of slope exposure on thickness of organic horizon and on content of organic matter

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