Dependence of the composition of the spectra of life forms of vascular plants from environmental factors in the Middle Volga region

In the article, the authors analyze the patterns of spatial variability of species richness, as well as the relative species richness of the life forms of vascular plants in the Middle Volga region. It is revealed that the shares of life forms in their spectra follow a geometric progression with the ratio d, characterizing the dominance of various life forms. Since the spectra of life forms depend on environmental conditions, the index d also depends on environmental factors. The equation of multiple regressions is calculated, showing the dependence of d on terrain features, climatic characteristics and soil types. Analysis of the obtained equation showed that the index d depends on the moisture supply of the region, average winter precipitation and temperatures. We have shown that the shares of the dominant life forms of vascular plants in the Middle Volga region - hemicryptophytes and annual grasses (therophytes) -are associated with the light level of the slopes. The authors note that the species richness as well as the indicator d does not depend on the light intensity.