Chemical composition of plant leaves as a functional sign of the formation of alpine plant communities

The content of C, N, P and the N:P and C:N ratios in plant leaves were studied in four alpine phytocenoses of the northwestern Caucasus to find out 1) how much the species found in them differ in chemical composition from random samples from the local flora; 2) how important the values of these characteristics are for dominance; 3) how phylogenetically conservative they are. The leaves of plants of alpine heaths and variegated fescue meadows contain less, and leaves of geranium-kopec meadows and alpine carpets contain more nitrogen compared to a random sample. Dominants of productive geranium-penny meadows contain more nitrogen than non-dominant species; for other communities, the opposite dependence is noted. Components of all communities, except alpine carpets, contain less phosphorus in their leaves compared to a random sample. The dominant species of alpine heaths contain less, and geranium-penny meadows contain more phosphorus in their leaves compared to non-dominant species. The C:N ratio in leaves is higher than random in species of alpine heaths and variegated fescue meadows and lower in other communities. The dominant species have higher C:N ratios compared to the others in all communities, except for geranium-penny meadows. The N:P ratio was higher than random in species of all communities except variegated fescue meadows. All characters except the C:N ratio have significant phylogenetic signal.