Conjugate occurrence of species in Alpine lichen tundra (northwest Caucasus)

УДК 581.552

Abstract

Natural phytocenoses are characterized by mosaic vegetation cover. Some species coexist well together, some are not observed near each other. In alpine lichen heaths, the height of vegetative plant organs rarely exceeds 3 cm and the overall size is also small. Between 2 and 14 species of vascular plants, not including mosses and lichens, were found in a 5 х 5 cm plot. By analyzing the co-occurrence and conjugate change in species abundance in the 5 х 5 cm quadrats, we had two Spearman’s pleiades of significant positive correlations associated with 7 common species. The smaller pleiad (together with the common species) has no internally significant negative correlations, but is associated negatively with slope steepness. The larger pleiad is associated positively with slope steepness (except for the species in common with the smaller pleiad), and can be divided into 3 groups of species associated with significant negative correlations. In addition, there are two species with significant negative correlations with all three groups. In both pleiades there are species with significant positive, negative or no correlations with soil depth - their common growth compensates for the high stoniness of the slope.