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Home , Landslide, Permafrost

, Phillips, Springman & Arenson (eds) © 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7

Geochemical properties of plant--permafrost systems on slopes, Yamal, Russia

N.G. Ukraintseva, I.D. Streletskaya, K.A. Ermokhina & S.Yu. Yermakov Lomonosov Moskov State University, Vorobyevy Gory, Moscow, Russia

ABSTRACT: Cryogenic on saline marine are widely distributed in a typical subzone of the . Interrelation between the height and productivity of willow tundra, and the activation of cryogenic processes is discussed. It is supposed that high willow canopies are the indicators of ancient landslide activity and may be used for mapping landslide areas. Various procedures are proposed to evaluate the relative age of the landslides. They include study of the cover succession, of the ash content in each vegetation group, and of the ground and chemistry on the landslide-affected slopes. It is shown that the landslide process causes the desalinization of the marine sediments and enriches the with salts. This is the important peculiarity of the cryogenic landslides in the region with saline permafrost distribution.

1 INTRODUCTION

Superficial cryogenic landslides are widely distributed in a typical tundra subzone of the Yamal Peninsula. They actively change the primary surface of ancient marine plains and terraces. The landslide-affected slopes cover up to 70% of the territory. The cryogenic landslides develop on surfaces consisting of fine- grained marine sediments with a high salinity. The permafrost table serves as a landslide shearing plane, or slide-surface. Outcropping of the frozen salty marine sediments took place due to seasonal sliding of the thawed water-saturated ground over the permafrost table. This process leads to sediment desalinization and enrichment of the active layer with salts. In addition to the mechanical dislocation of the deposits by a landslide, lateral redistribution of elements within the active layer is observed (Dubikov 2002, Lewkowicz – Study site (station “Vaskiny Dachi” ) 1990, Leibman 1995, Romanovskii et al. 1996). – Sites of the observed landslide – Southern boundary of the frozen saline marine deposits (after Dubikov 2002, and Brushkov 1998). 2 STUDY AREA AND METHODS Figure 1. Study area in West . The research is based on data obtained from the “Vaskiny Dachi” since 1988. This station is located on Phytomass was selected according to the layers: the Yamal Peninsula (from 70°15N, 68°51E to shrubs from a site of 5 5 m size, and herb and moss 70°20N, 68°56E) within a typical tundra landscape layers from sites of 0.5 0.5 m size. Weight of the (Fig. 1). The monitoring of the landslide includes samples in air-dry state was expressed as g/m2. In the study of the a) vegetation cover succession, b) ash laboratory, semi-quantitative spectral and X-ray–fluo- content of each vegetation group, c) ground water rescent analyses of air-dried and homogenized plants extraction chemistry, d) element composition in and soils were carried out with the help of XRF spec- and sediments using water extraction. The field sam- trometers ORTEC-TEFA. The main ions in filtered ples of the vegetation, soil, permafrost, and ground soil water extraction were determined by standard water were obtained at selected points of the cross- chemical methods of soil analysis. Ground water sections traversed landslide-affected slopes (80 samples were collected at selected points to character- points). Detailed leveling of the relief, thawing depth ize water chemical composition. measurement with a dip-stick, and description of the Three large landslide-affected slopes have been vegetation cover were carried out on the cross-section. studied since 1996: I. the “Lake” site, is oriented to

1149 the south, about 1000 m long, and between 22 to 47 m acutiflorum, Ranunculus borealis etc.) with active a.s.l.; II. the “Triangular” site, is oriented to the north, willow restoration, as observed on old shearing planes 350 m long, and between 43 to 53 m a.s.l.; and III. the (B2, see Table 1). The next stage is colonization by the “Cirque” site, is oriented to the north, 700 m long, and high willow/meadow parkland communities (B3). between 23 to 48 m a.s.l. Five or more landslides are On young landslide bodies (C1) low shrubs (willow, noticed on each slope. Some landslides are newly dwarf-birch) are dominating, moss cover degrades, formed and rarely covered with pioneer . The pioneer vegetation (Calamagrostis sp., Poa alpigena others are covered by light-green meadow vegetation. subsp. alpigena, Equisetum arvense subsp. boreale, The oldest landslides are overgrown with shrub vege- Polemonium acutiflorum, Ranunculus borealis and tation (Salix glauca dominating). These observations cotton-grass) is restoring. On C2 high willow/meadow suggest that cryogenic landslides are cyclic in time in communities with mosses replace them. Dense willow various parts of the landslide-affected slope. As a canopies covering moss/herbaceous communities domi- result of the process, the slopes represent a landslide nate on ancient landslide bodies (C3). system of various ages with a specific set of morpho- The different stages of landslide vegetation provide logical elements: (A) tops of the hills and convex stable the criteria to estimate the relative age of landslides. slopes (not affected by landslides), or a “background”; Thus, background surfaces, not disturbed by landslides (B) concave cirque-shaped (shearing (A3), young shearing planes (B1) and young landslide planes), or denudation zone; and (C) hummocky scarp bodies (C1) can be clearly distinguished by the herba- and terraces (landslide bodies), or accumulation zone. ceous community. Old and ancient landslides are simi- The landslides of three generations are studied: (1) lar in vegetation cover, but differ in height and density the young, formed 10 to 30 years ago; (2) the old, of the shrub layer (Table 1). High willow communities formed up to 300 years ago; and (3) the ancient, (50 cm) occupy the most ancient landslide slopes. formed 300 to more than 2,000 years ago. According to the structure of their phytomass, land- The age of some landslides is estimated using slide-affected slopes differ distinctly from background radiocarbon dating of buried organic matter (Leibman surfaces. On background surfaces mosses cover 100%, et al. 2000). In other cases, the serial changes of veg- and willow cover less than 10–15% of the area. On the etation or other methods are used as an indicator of landslide-affected slopes the willow quota increases up landslide age (Table 1). to 50–80%, and less than 40–80% is covered by mosses (Ukraintseva et al. 2000). The above-surface phytomass of ancient landslides is higher than that of the back- 3 RESULTS AND DISCUSSION ground – on average about 1400 g/m2 compared to 850 g/m2 of the background (Fig. 2). Thus, high willow 3.1 Change of vegetation on the canopies are the indicators of an ancient landslide activ- landslide-affected slopes ity and may be base of the landslide areas mapping.

Willow shrubs are usually considered as the early 3.2 Desalinization of the marine sediments due to stage of serial changes of vegetation, which colonize landsliding bare surfaces formed due to natural or/and anthro- pogenic processes (McKendrick 1987, Jumponen et al. In study area marine sediments are preva- 1998, Matsuda et al. 1988 and Andreev 1970). The lent. The amount of water-soluble salts in the changes predominance of high willow canopies (Salix glauca) on landslide-affected slopes is noticed by Rebristaya et al. (1995), Ukraintseva (1997), Ukraintseva et al. (2000). The dominating communities on hilltops and stable slopes (A3) in the study region are the under- shrub/grass/moss and moss/lichen tundra (Table 1). They are the background for a subzone of typical tun- dra. After 10 to 15 years since the landslide event, bare spots alternate with pioneer herbages, such as Puccinellia sibirica, Poa alpigena subsp. alpigena, Deshampsia sp., Phippsia concinna etc. and forbs Tripleurospermum Hookerii on young surfaces (B1, Herbaceous Moss Mortmasse Table 1). The second stage is colonization by meadow Willow Dwarf-birch sedge/grass communities (Calamagrostis sp., Poa alpigena subsp. colpodea, Carex concolor, Nardosmia Figure 2. Above-surface phytomass of vegetation cover at frigida, Equisetum arvense subsp. boreale, Polemonium landslide-affected slopes and “background” surfaces.

1150 – 3 3 3 – 72 40 100 0 0 33 1 2 80 80 1 1 C3 – 55 150 170 170 36.6 35.9 23.6 1 111 121 85 70 55 III I III – 53 1 3 3 2 1 1 2 3 2 2 3 3 2 2 B3 1223 – 53 1 3 1 3 3 1 C2 2 1 – 55 3 23131 311 3 1 11 2 2 2 B2 1 – 10 7 – 83 2133333 1 2 1 1 2 2 1 2 3 3 3 3 3 3 3 3 3 – 88 49.0 27.6 26.4 47.6 23.7 42.0 38.8 50 100 50 30 130 100 115 40 90 30 90 80 65 90 50 3 1 33 223 3 – 50000000 50 80 10 20 75 70 20 20 3 3 3 111 21222 112 111 I II III I II I II I 3 1 3 1 3 3 3 2 2 3 3 1 1 C1 3 3 3 2 40 60 55 80 60 60 55 85 ve age of the landslides. ve – 10 1 – 25 3 – 87 1 12 3 1 1 – 77 1 2 3 3 21 B1 1 1 1 1 1 many (Rabotnov 1978). (Rabotnov – many – 25 average, 3 – average, 1 1 few, 2 1 – few, 20 15 30 0 0 0 50 47.7 52.7 48.8 30.2 49.5 33.8 25.3 95 90 95 1 0 0 50 1 1 3 3 1 60 70 35 15 60 20 5 10 5 0 0 0 5 3 3 3 21 3 1 2 1 1 20 5 10 0 0 0 70 111 1 1 1 A3 I II III I II III 1 1 1 1 1 1 1 3 1 2 1 1 1 0 0 1 2 1 1 minus 2 3 3 boreale alpigena subsp . colpodea subsp. sp. sp. Polytrichum juniperinum Polytrichum cucullata Cetraria Cladonia rangiferina Dicranum elongatum Dicranum Aulacomnium turgidum Aulacomnium Ptilidium siliare Parnassia palustris Parnassia Moss cover, % Lichen cover, % Polygonum viviparum Polygonum alpigena Poa Mnium Hylocomium splendens Carex concolor Carex uncinnatus Drepanocladus Undershrub-herbs cover,Undershrub-herbs % Salix glauca Betula nana acutiflorum Polemonium Ranunculus borealis frigida Nardosmia Shrub cover, % Shrub height, cm subsp . arctica rubra Festuca Equisetum arvense subsp. Poa arctica Poa vitis-idaea subsp. Vaccinium Phippsia concinna alpigena Poa Alopecurus prateum sp. Calamagrostis Holmii Calamagrostis Carex arctisibirica Carex groenlandica Calamagrostis Rubus chamaemorus Puccinellia sibirica Hookerii Tripleurospermum Deshampsia Table 1.Table as an indicator of the morphological elements and the relati The vegetation Morphological elements slopes of the landslide affected of the study site Index m see level, Height above Slope, degree Cladonia sp. *Abundance of species after Braun-Blanquet systems:

1151 from 0.2 up to 1.5%, ions Cl and Na dominates 2000 years) the salinity of soil and sediment is only (Dubikov 2002, Brushkov 1998, and Tsibulsky 1995). 0.04 to 0.08% (Table 2). However, the salt content of Chemical composition of soil and ground water on the ground water is relatively high with 2–10 g/l on the landslide-affected slopes proved, that they were really young shearing planes (10 to 11 years), and 0.3–1.5 g/l generated on the salted marine sediments, which out- on the ancient ones. The salinity values of ground cropped due to landslide event (Figs. 3, 4). of ancient shearing surfaces are widely scat- The salinity of clayey soil (using filtered soil water tered. Values 0.3–0.5 g/l prevails, but on separate local extraction) in the active layer of a young shearing sites salinity makes up to 4–5 g/l. This indicates that the plane (formed 1989 to 1990) was 2% and decreased to areas of salt accumulation and salt removal exist simul- 0.1 to 0.7% in 2000. The active layer is gradually desali- taneously in ground water on the ancient landslides. nated due to and drainage during warm In our opinion, the saline water is accumulated in seasons of the year. On ancient shearing planes (up to local depressions, and forms highly saline lenses of ground water in the active layer. The permafrost table is locally decreased due to heating influence of the saline water. The depressions, formed at the permafrost table, -80 -60 -40 -20 0 20 40 60 80 called “salt traps”, constantly feed the active layer with meq/l salty water. Such “salt trap” is observed at the boundary between the ancient landslide body and its correspon- HCO3 CL SO4 Ca Mg Na K ding shearing plane. Although the depth of the observa- Figure 3. Chemical composition of ground water on an tion shaft was 1.6 m, the permafrost table was not ancient shearing surface. exposed, despite the fact that the thickness of active layer on the slope was less than 0.9 m on the average meq/100g (Table 2). The temperature of sediments, measured 31 Depth -4 -3 -2 -1 0 1 2 3 4 August by a thermal dip-stick in the same shaft, even at cm the 3.4 m depth was 0.3° centigrade. The level of ground waters was established on depth of 0.8 m in the 20 Loam shaft. The total salinity for obtained ground water sam- ple is much high and constitutes 4.68 g/l. 40 Loam The salt content of soil and sediments sampled in same shaft, according to water-extraction data, did not 75 exceed 0.04% (at the depth between 0.0 and 1.0 m) 100 and 0.14 to 0.20% (at the depth interval of 1.0 to 1.6 m). Clay Sediments of the bottom interval can be referred to poorly salted (Dubikov 2002). The domination of Na 140 Clay and Cl ions in chemical composition of ground water 165 and superficial sediments proves marine origin of the native deposits (Figs. 3, 4). HCO3 CL' SO4" Ca" Mg" K' Na' Such the lenses of highly salted ground water were to be found in other key-areas: at Bolshaya Ledyanaya Figure 4. Chemical composition of soils and bedding Gryada (to the north of confluence of Mordy-Yakha sediments (using water extraction) on ancient shearing and Se-Yakha), and on the eastern of Khalev-To plane. Lake as (Dubikov 2002). They are the important

Table 2. Geochemical features of landslide-affected slopes. Elements of slopes A3 B1 B2 B3 C1 C2 C3 Thickness of active layer, cm 53.3 111.7 69.0 75.0 88.3 88.8 84.5 Salinity of soil water extraction, % 0.02 0.28 0.09 0.04 0.70 0.03 0.03 Salinity of ground water, g/l 0.1 9.88 2.79 1.53 2.89 0.73 0.31 Ash content of: – willow leaves, % 4.05 – 6.81 5.26 7.73 5.90 5.52 – grasses, % 4.65 11.4 7.7 7.1 16.1 9.7 8.26

1152 peculiarity of the cryogenic landslide process in the 4 CONCLUSION region with saline permafrost distribution. Superficial cryogenic landslides are widely distributed in a typical tundra subzone of the Yamal Peninsula. 3.3 Relation between landslide elements, active They actively change the primary surface of ancient layer thickness and element composition of marine plains and terraces. The landslide-affected plants, soils, sediments and ground water slopes cover up to 70% territory. Landslide process influences the vegetation cover The various morphological elements of the landslide- of the study area. Instead of background undershrub/ affected slopes define the dynamics of the permafrost grass/moss and moss/lichen tundra, the landslide slopes table. The stable slopes (A3) are characterized by a have serial changes of vegetation: from primary stable position of the permafrost table (on average herbages up to high willow/meadow parkland com- about 53 cm, Table 2). The shearing planes of all ages munities. The different stages of landslide vegetation (B1, B2, and B3) are characterized by the removal of provide the criteria to estimate the relative age of sediment and soil. The permafrost table follows the landslides. surface morphology leading to thawing of perennial Landslide-affected slopes differ distinctly from the frozen ground (lowering of permafrost table). The background surfaces by structure of their above-surface landslide bodies override each other in the zone of phytomass. The fraction of willow may attain 50–80% accumulation, and buried layers refreeze thus, active on ancient slopes, while the moss cover dominates on layer thickness remains constant (raise of permafrost the stable background surfaces. The phytomass reserve table). The thickness of the refrozen deposits is 5 m and of the ancient landslides is also higher than that of the more (Ukraintseva & Streletskaya 1999). background – on average about 1400 g/m2 compared to Geochemical features of the various morphological 850 g/m2 of the background. Therefore, high-willow- elements of the landslide-affected slopes are shown in canopy areas could be used as the indicator for landslide Table 2. The results of chemical analysis indicate that mapping based on aerial and space photographs. the morphological elements of slopes differ in their The various morphological elements of the land- salinity and ash content of plant. The minimal values of slide-affected slopes define the dynamics of the per- all parameters are peculiar to background stable slopes. mafrost table. The stable slopes (A3) are characterized Depth of thawing corresponds to the zonal features of by a stable position of the permafrost table. The shear- the area, and low soil and sediment salinity of the active ing planes of all ages have low permafrost tables. The layer is connected to the dilution by precipitation, run- landslide bodies override each other in the accumu- off and drainage during the warm seasons of the year. lation zone, and the permafrost table raises and The young shearing planes and landslide bodies (B1, encroaches below the buried landslide layers. C1) are much more saline compared to background Various methodical procedures have been proposed to surfaces because the landslides outcrop the salty marine evaluate the relative age of landslides: 1) studying of the sediments. Then salinity is gradually reduced – from old succession phases of vegetation cover on the landslide- to ancient landslips, but it remains higher than back- affected slopes; 2) analysis of the ground water and sed- ground’s salinity. The same trend is typical for the depth iment salinity, and 3) determination of the ash content of of thawing: the young landslides have 1.5–2 times each vegetation group. The most informative indicators higher thickness of an active layer, than the stable sites for the landslide age are salt content of ground water, (Table 2). and ash content of grasses. The other parameter may Salt content of ground water and ash content of hardly be used for the landslide age determination. grasses seem to be most informative for the relative The enrichment of an active layer with chemical age estimate of landslides. Other parameters are less element takes place in the process of the desaliniza- significant because of low value variability. However, tion of marine sediments on landslides. This is the the salinity of ground water varies not only from year important peculiarity of the cryogenic landslides in to year but depends on weather conditions. For example, the region with saline permafrost distribution. the analyses of samples obtained on a shearing plane of the landslide formed in 1989 has shown that the salinity of ground water in 1997 (rainy and cold year) ACKNOWLEDGMENTS was 7 g/l, whereas that in 2000 (dry and warm period) increased up to 13 g/l. Therefore, to determine the The research was funded by the RFBR financial support relative age difference, water samples must be taken (grant 98-05-65061). Authors express their gratitude to simultaneously, during a short term period to elimi- M.O. Leibman for the fieldwork organization and nate influence of local weather conditions (e.g. evapo- help in data processing, and also to S.E. Sorokin and ration, dilution by precipitation). R.V. Grishina for processing the chemical analyses.

1153 REFERENCES McKendrick, Jay D. 1987. Plant Succession on Disturbed Sites, North Slope, , U.S.A. and Alpine Andreev, V.N. 1970. Some geographical laws in the distri- Research. 19(4): 554–565. bution of above-surface phytomass in tundra zone in Rabothov, T.A. 1978. Phytosociology. Moscow: MSU (In connection with progress to the north of tree-shrubs Russian). vegetation. Biological basis of nature usage in the Rebristaya, O.V. et al. 1995. Dynamics of vegetation on North. Syktyvkar: Komi Publisher (in Russian). cryogenic landslides in the central part of Yamal Brushkov, A.V. 1998. Salt frozen deposits of the Arctic Peninsula. Botanical Journal, 80(4): 31–48 (in coast, their origin and characteristics. Moscow: MSU Russian). (In Russian). Romanovskii, N.N., Gravis, G.F., Melnikov, E.S. & Dubikov, G. I. 2002. Composition and cryogenic structure of Leibman, M.O. 1996. Periglacial processes as geoindi- permafrost in West Siberia. Moscow: GEOS Publisher cators in the cryolithozone. In: A.R. Berger, & (In Russian). W.J. Iams (eds.). Geoindicators. Assessing rapid envi- Jumponen, A., Mattson, K., Trappe, J.M. & Ohtonen, R. ronmental changes in systems: 47–68. Rotterdam: 1998. Effects of Established Willows on Primary Balkema. Succession on Lyman Forefront, North Tsibulsky, V.R., Valeeva, E.I. & Moskovchenko, D.V. et al. Cascade Range, Washington/U.S.A.: Evidence for 1995. Environmental nature of Yamal. In 2 volumes. Simultaneous Canopy Inhibition and Soil Facilitation. V. 2. Tyumen: Inst.of Nortern Development, SB RAS Arctic and Alpine Research 30(1): 31–39. (in Rus.). Leibman, M.O. 1995. Preliminary results of cryogenic Ukraintseva, N.G. 1997. Willows tundra of Yamal as the landslides study on Yamal Peninsula, Russia. Permafrost indicator of salinity of superficial sediments. Results and Periglacial Processes 6: 259–264. of basic research of Earth in Arctic and Leibman, M.O., Archegova, I.B., Gorlanova, L.A. & . Novosibirsk: Nauka Publisher (in Russian). Kizyakov, A.I. 2000. Stages of cryogenic landslides Ukraintseva, N.G. & Streletskaya, I.D. 1999. Landscape on Yugorsky and Yamal Peninsulas. Earth Cryosphere indication of surface soil on West Yamal landslide IV(4): 67–75 (In Russian). slopes. In K.N. Dyakonov, I.I. Mamai (eds.), Lomonosov Lewkowicz, A. 1990. Morphology, frequency and magnitude Moscow State University Landscape School: Traditions, of active-layer detachment slides, Fosheim peninsula Achievements, Future, 120-129. Moscow: RUSAKI Ellesmere Island, N.W.T. Permafrost-. Proc. of (In Russian). the Fifth Canadian Permafr. Conf., Univ. Laval, Ukraintseva, N.G. & Leibman, M.O. & Sreletskaya, I.D. Quebec: Collection Nordicana 54. 2000. Peculiarities of Landslide Process in Saline Matsuda, K., Sasa, K. & Shimizu, O. 1988. Observations of Frozen Deposits of Central Yamal, Russia. In: E. Geomorphic and Vegetational Changes Caused by Bromhead et al. (eds.) Landslides in research, theory Thermal of an Involuted Hill in , and practice. Proceedings of the 8th International N.W.T., Canada. Characteristic of the massive ground Symposium on Landslides, Cardiff UK 26-30 June ice body in the Western Canadian Arctic related to 2000, 3: 1495–1500. London: Thomas Telford. paleoclimatology, 1984–1985. Hokkaido: Inst. Low Temp. Sci., Hokk. Univ.

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