ИСТИНА

In the beginning of the XXI century in tundra growth of plant productivity and vegetative index (NDVI) was revealed (Walker, et. al. 2012; Bhatt, et. al. 2013; Belonovskaya et al., 2016; Tishkov et al., 2016). Comparing of the results of remote sensing and terrestrial investigation in the beginning of the century (2000) and our time (2015) in Russian Arctic shows progressive expansion of the forest vegetation at the northern limit. According to the analysis of satellite images the trend of growth of productivity (more than 25-30%) and increasing of herbaceous plants’ share in the tundra communities were observed. Over the past decade the average value of the NDVI index increased, which reflected the degree of "greening" of the territory, due to an increase in the number and length of the growing period. The main cause of this process is synergism of climatic (permafrost melting, changes in rainfall and snow accumulation) and anthropogenic impact changes. Growing season’s increasing, active temperature sum’s raising and soil melting depth’s deepening result the artic vegetation communities’ structure and life forms spectrum transformation. First of all, the trend of scrub vegetation invasion was recognized for various treeless biomes. This process concerns the increasing of biomass, abundance and cover of tundra shrubs: Betula, Salix, Dusсhekia, Pinus, Juniperus, etc. genera spreading in Russian tundra (Kola Peninsula, Lower Pechora-river, Yakutia). Also the reducing of lichens and mosses, and increasing of grasses coverage were recorded there. The so called "greening" of tundra was also associated with fires and overgrazing of domestic reindeer. Identified current trends in artic vegetation coincided with the changes of distribution and abundance of indicators in terrestrial fauna of Russian Arctic (geese, sandpipers, reindeer, lemmings, polar fox), which could be interpreted as the effects of tundra habitat’s “greening”: for example, the increasing in the abundance and changes in migration routes for geese, stopping 3-4 years oscillates of the lemmings’ population in some regions, the transformation of continuous distribution of reindeer. The obtained results are important for the Artic biodiversity conservation.