Relationship between Phytocenotic Diversity of the Northeastern Transbaikal Orobiome and Bioclimatic Parameters

Abstract

The most important spatial patterns of plant cover of the Northern Transbaikalia, its regional features being represented by the structure of altitudinal zonality of the Northeastern Transbaikal orobiome, have been determined in relationship with the climatic factor. The regional climate assessment of the altitudinal belt structure of the plant cover of the orobiome has been performed for typological subdivisions of the highest hierarchic level (phratries of the classes of plant formations) using the BioClim global climate model. Principal component analysis, discriminant and cluster analysis were used to demonstrate that the summer ombrothermic index, continentality and climate moisture indices and the mean annual rainfall of many years are the most significant bioclimatic parameters determining the spatial structure of plant cover in the mountain taiga, subgoletz, mountain tundra and goletz belts. The background communities of orobiome belts develop under the conditions of continental climate (continentality index from 36 to 50). Heat supply parameters, first of all, in the vegetation period, are crucial for the spatial differentiation of altitudinal subelts, characterizing the change of light forest and dwarf pine communities in the subgoletz belt, larch, larch-pine and dark-coniferous forests in the mountain taiga belt. Moisture supply is related to the regional differences in the typological diversity of the belts, which are manifested in the development of more moisture-demanding fir-spruce forests in the low parts of the Patom Highland (rainfall amount more than 450 mm per year) and pine forests in the intermountain basins of the Stanovoy Highlands, existing under the conditions with the maximum annual temperature amplitude and low rainfall levels (up to 400 mm per year).