Variety of grass-shrub layer of birch forests of Teberdinsky reserve and natural park "Upper Gunib"

Communities dominated by Betula litwinowii Doluch have been studied in Teberdinsky Reserve (Karachay-Cherkessia) and the Natural Park "Upper Gunib" (Dagestan). The assessment of the grass-shrub layer for 5 groups of communities of high-altitude birch forests was carried out using the indices of Menhinik, Margalef, Shannon, Simpson, Shannon-Weaver equalization index and dominance index, reflecting different aspects of biodiversity. The comparison of the obtained indicators of equalization of the grass-shrub layer of mountain birch forests of the studied regions of the North Caucasus with the literature data was carried out. It is shown that values of indices of Margalef and Menhinick exhibit greater scatter of the average values. With high species richness, Simpson and Shannon indices have medium-high values. Indices are determined, which enable to estimate the level of biodiversity in mountain birch communities most objectively, and allow to comparing syntaxons of these communities.