Plant cover of sandy deflation scars in reindeer-grazed tundra

The upper parts of the sandy hills in the East of the Malozemelskaya Tundra are characterized by sandy deflation scars (areas 200 3000 m 2 ; depths 0 1.5 m) in lichen-dwarf shrub tundra. The kettles are most common close to reindeer herders' camps and settlements. The vegetation cover in sandy areas of the tundra zone has been studied by Andreev and Sambuk in the 1930s and by Pristyazhnyuk & Telyatnikov (1995); Khitun & Rebristaya (1997) and Magomedova & Morozova (1997). The purpose of my study was to ascertain the state of vegetation cover of such ecotopes and their response to the effect of anthropogenic factors, one of which is reindeer grazing. As part of the study we have tried to find out if there exist connections between reindeer graz¬ ing and the occurrence of kettles.


Study area and method
The upper parts of the sandy hills in the East of the Malozemelskaya Tundra are characterized by sandy deflation scars (areas 200 -3000 m 2 ; depths 0 -1.5 m) in lichen-dwarf shrub tundra.The kettles are most common close to reindeer herders' camps and settlements.The vegetation cover in sandy areas of the tundra zone has been studied by Andreev and Sambuk in the 1930s and by Pristyazhnyuk & Telyatnikov (1995); Khitun & Rebristaya (1997) and Magomedova & Morozova (1997).The purpose of my study was to ascertain the state of vegetation cover of such ecotopes and their response to the effect of anthropogenic factors, one of which is reindeer grazing.As part of the study we have tried to find out if there exist connections between reindeer graz¬ ing and the occurrence of kettles.
In the field season of 1998, we made 58 descrip¬ tions of plant cover of sandy deflations on sampling plots of5mx5m (Kucherov & Payanskaya-Gvozdeva, 1995) that allowed us to describe a rela¬ tively homogenous plant cover.The following parameters were used: species composition, cover percentage, abundance of cryptogamic and vascular plants, plant height, and features of soil.

Results and discussion
The plant cover of the sandy deflation scars was het¬ erogeneous.Four types of plant communities were found in these ecotopes.Type 1 -communities were dominated by Empetrum hermaphroditum + Arctous alpina and situated on hillocks, at the periphery and Rangifer, Special Issue No. 13,2002 sometimes in the center of sandy deflation kettles, which presented fragments of destructed tundra.The species composition and diversity of life forms in these communities is similar to those of the bor¬ dering moss -lichen -dwarf shrub tundra.Type 2communities of Racomitrium canescens -Empetrum hermaphroditum occurred on gently sloping hillocks sit¬ uated closer to the centre of the soil-blowing kettles.The communities of type 3 (Stereocaulon rivulorum -Polytrichum piliferum) occurred on the less steep sur¬ faces of the deflation scars, in which spore plants predominated.Primitive plant aggregations in the communities of type 4 (cryptogramic crusts -Polytrichum piliferum) were at the central part of deflation scars, where pebbles and stones predomi¬ nated.Species composition was variable in such groups.This type belonged to a last stage of degra¬ dation of native plant cover and becomes the starting stage for further colonization and overgrowth of sands.
The comparative analysis of these communities of sandy scars revealed the following: species diversity decreased from the first to the fourth type; total plant cover decreased from type 1 (86%) to type 4 (3%), consequently the proportion of open substrate increased.There was an accompanying change in coverering of different plant groups.The frequency of plant species also decreased from type 1 to type 4. The cover of mosses and lichens increased, while cover of dwarf shrubs and shrubs decreased.The ori¬ gin of such changes in plant cover of scars may be owing to reduced competition by vascular plants.Increased number of xerophytic species of vascular plants, mosses and lichens of community type 4 con¬ firms deterioration of growing conditions in this type of communities.Variability of species composi¬ tion was the highest in open communities, owing to increased instability of plant growing conditions.
The described changes in plant cover of sandy hills are most probably caused by anthropogenic impact.Reindeer numbered 2340 in the investigated area (Zolotoy, 1999) and grazing in the lichen and dwarf shrub-lichen tundra on sands may be the most important factor in stopping natural development of vegetation cover and causing changes or even total destruction of it.This situation is connected with the deterioration of plant life conditions caused by increased wind erosion.The latter disturbs the mois¬ ture regime of the soil.Pebbles on the soil surface also hinder regrowth of plants.Such open areas can persist over the long term, a conclusion proved by registered mapping in 1969 and air photographs in 1984.