A phylogenetic analysis of plant communities of the Teberda State Biosphere Reserve

Abstract

A phylogenetic analysis of communities was conducted based on a comparison of the distances on a phylogenetic tree between species of the studied community and the distances in random samples taken from local flora. This made it possible to determine the extent to which community composition is formed by more closely related species or, on the contrary, it is more even and includes species that are less closely related to each other. The first case is usually interpreted as a result of a strong influence caused by abiotic factors, due to which species with a similar ecology (which are a priori more closely related) would remain. In the second case, biotic factors such as competition may lead to community formation among distant clades due to the divergence of their ecological niches. The goal of the study is to explore the phylogenetic structure in communities of the Northwestern Caucasus at two spatial scales, the scale of an area from 4 to 100 m2 and a smaller scale within a community. The list of local flora of the alpine belt has been composed with a database of relevees carried out in Teberda State Biosphere Reserve at altitudes exceeding 1800 m. It includes 585 species of flowering plants belonging to 57 families. Basal groups of flowering plants are not represented in the list. At the scale of communities, three classes, namely Thlaspietea rotundifolii-communities formed on pebbles, Calluno-Ulicetea alpine meadows, and Mulgedio-Aconitetea subalpine meadows, have not demonstrated significant distinction of phylogenetic structure from random model. At the intracommunity level, a larger proportion of closely related species (clustered community) was detected for alpine meadows. Communities developing on rocks (class Asplenietea trichomanis) and the alpine community (class Juncetea trifidi) are closely clustered. At the same time, even alpine lichen heaths proved to have a phylogenetic structure at a small scale. Alpine snowbeds (class Salicetea herbaceae) that develop under the conditions of winter snow accumulation were more even at both scales, i.e., they contained more diverse and distantly related plant species compared with random samples. Scheuchzerio-Caricetea fuscae fen communities in cold springs (Montio-Cardaminetea), sedge springs (Carici rupestris-Kobresietea bellardii), and communities in which shrubs predominate (Juniperus and Rhododendron elfins, class Loiseleurio-Vaccinietea) have been studied only at the larger scale and showed significant uniformity of species composition, i.e., they were phylogenetically more diverse as compared with random samples.