ИСТИНА

Interrelation between the height and productivity of willow tundra, and activation of cryogenic landsliding is discussed. Cryogenic landslides on saline marine sediments in Typical tundra subzone of the Yamal Peninsula show specific features. Landslide process causes desalinization of marine sediments and enriches the active layer with salts. Landforms of the landslide-affected slopes can serve as indicators of permafrost table change, heterogeneity of saline composition of near-surface sediments. It is suggested that high willow canopies are indicators of ancient landslide activity. Landslide- affected slopes significantly differ by structure of phytomass from stable surfaces (background): on landslide slopes willow proportion in phytomass reaches 50-80%, while background surfaces are dominated by moss (60-70%). The total aboveground phytomass on ancient landslides (an average of about 1,600 g/m2) is much higher than on stable surfaces (an average of about 1200 g/m2). Most informative landslide age indicators are: salinity of sediments and ground water, macro- and trace-element concentration, ash content in willow leaves and grasses. Concentration of chemical elements can either increase with age, or decline. This is obviously due to the mobility of an element migrating in the active layer.