Leaf functional traits and ecological strategies are important for the formation of subalpine fens and tall-herb plant communities

Plant functional traits are important for the formation of plant communities and for plants’ ability to dominate there. The comparison of mean trait values of organisms within community with that for the random samples of the local biota allows estimating the importance of the trait for the formation of the community composition. The comparison of mean and community weighted mean values allow estimating their role for the dominance in any given community. We studied leaf functional traits (leaf area, mass, specific leaf area — SLA, leaf dry matter content — LDMC), as well as the contribution of Grime’s CSR strategies scores (competitors — stress-tolerators — ruderals) in two subalpine communities at the Teberda National Reserve (the North-Western Caucasus, Russia). Many leaf functional traits and plant strategies differ significantly in the fens and tall-herb communities from the random set of the species belonging to the local high mountain flora. The tall-herb community species have larger size (area and mass) of leaves, higher SLA and lower LDMC, as well as higher contribution of C and lower contribution of S and R strategies. The dominants of this community differ from the subordinate species by even larger leave size, lower SLA, higher LDMC higher C and lower R strategy scores. The plants of subalpine fens, in compare with random set of species, have smaller leaf size, lower SLA and higher LDMC, higher contribution of stress-tolerancy (S) and lower contribution of C and R strategies scores. In compare with subordinate species, the dominants of subalpine fens have even lower SLA and higher LDMC, higher S and lower R strategy scores. Thus, under the same climate conditions in depressions of mesorelief, but under the different hydrological conditions, in the subalpine belt of mountains there are plant communities with the contrasting functional structure. This underpins the important role of moisture conditions for the establishment of the spatial pattern of high mountain communities.