Plant species distribution, Rock particle size and their structural-functional organization in the rocky habitats of the Western (Svaneti) and Eastern (Kazbegi) regions of the Central Great Caucasus

Author: Tamar Jolokhava
Keywords: rock particle size, soil formation, plant species distribution, primary succession, rocky environments
Annotation:

Subnival habitats of the Central Caucasus represent typical rocky environments with very sparse soil cover and patchy vegetation. We studied how plant species spatial distribution in a subnival habitat (alpine-nival ecotone) depends on the size of rock particles. We described the distribution patterns of plants and rock particles of various sizes, and examined the possible links between these patterns using correlation analysis and multivariate tests. We found that, while large-sized rock particles (6-20cm; 20-60cm) prevailed on the surface, most plants were associated with relatively rare fine-grained substrata and, to a lesser extent, with even rarer soil-covered spots. In addition, there were species that showed a pronounced preference for soils, while still other species prefered mid-sized rock particles. Our results show that the differential preference of species for certain sizes of rock particles observed in our study can conform well to the patchy pattern of vegetation typical for subnival habitats: many species that prefer a fine-grained substratum might clump together at such fine-grained spots and form the patches of associated plants provided there are facilitative interactions among them; the species that prefer coarser-grained substrata might establish as solitary plants outside of the patches.