VARIABILITY OF THE COMPOSITION AND RATIO OF VASCULAR PLANT LIFE FORMS IN ECOTONE COMMUNITIES OF THE UPPER BORDER OF WOODY VEGETATION IN THE POLAR URALS

Abstract

For phytoindication of ecotopic conditions according to the degree of moisture and heat supply, full floristic composition was used in a number of communities and ecotopes within them. Different hydrothermal regimes of ecotopes underlie the distribution of life forms of vascular plants. The spatial heterogeneity of floristic diversity is largely due to a set of species of grassy life forms. Woody life forms are not numerous, but play a significant role in the structure of the vegetation cover. The species richness of communities naturally decreases during the transition from larch forests and woodlands to mountain tundras with single trees. At the same time, communities are largely similar in species composition, and the set of life forms is preserved, but the composition and ratio of different types of life forms change. The transition from smooth variability in the composition and ratio of life forms to markedly increased variability as a result of natural environmental factors is clearly visible, which is correspondingly reflected in a decrease in indicators of species similarity of communities.