Chemical Composition of Plant Leaves as a Functional Trait of the Formation of Alpine Plant Communities

Abstract

Contents of C, N, and P and N : P and C : N ratios in plant leaves have been studied in four alpine phytocenoses of the northwestern Caucasus to find out whether the species encountered in these areas differ in chemical composition from random samples from the local flora or not and determine the significance of the values of these traits for dominance, as well as their phylogenetic conservation. The content of nitrogen is lower in the leaves of plants from alpine heaths and Festuca varia grasslands and higher in the leaves of species of Geranium–Hedysarum meadows and alpine snowbeds than in a random sample. Dominants of productive Geranium–Hedysarum meadows contain more nitrogen than nondominant species, while the opposite dependence has been recorded for the other communities. The leaves of the components of all communities except alpine snowbeds contain less phosphorus than a random sample. Dominants of alpine heaths have less phosphorus and Geranium–Hedysarum meadows have more phosphorus in the leaves than nondominant species. The C : N ratio in the leaves is higher than the random value in species of alpine heaths and Festuca varia grasslands and lower in other communities. The dominant species have higher C : N ratios than the other species in all communities except Geranium–Hedysarum meadows. The N : P ratio is higher than the random value in species of all communities except Festuca varia grasslands. All the traits except the C : N ratio have a significant phylogenetic signal.