Functional Traits in Plants and Diversity of Subalpine Bromus variegatus Grasslands in the Northwestern Caucasus

The study assesses the role of leaf functional traits (area, mass, specific leaf area, and water content) and plant height, as well as Grime’s CSR strategies, in plant community formation and dominance on the subalpine Bromus variegatus grasslands (BVG) of the Northwestern Caucasus. BVGs evolve in the conditions of snowless winter and deep soil freezing and are unique pastures for high-altitude ungulates. We tested the hypothesis that plant community combines features of stress-tolerants (S) and ruderals (R) and that plant traits and strategies on BVG differ from the previously studied highland communities of the Caucasus. The mean of aboveground biomass is 349 ± 15 g/m2. Comparison of the mean species trait values with a random sample of a local flora revealed the importance of all studied traits for species selection into community, for instance, leaf size characteristics in grasslands are 10 times lower than in the model community. Comparison of mean and weighted mean shows that dominants of community have smaller dry and stiff leaves at higher functional height of the individual. The mean values of C : S : R contribution are 26 : 45 : 29%. The high contribution of stress tolerant strategy is important both species selection into grasslands and dominance in them. High richness (FR) was recorded for the leaf water content. Divergence (FD) was high only for leaf size traits.