Высотная дифференциация лесных формаций на западном склоне Южного Урала (район широколиственно-темнохвойных лесов)

Abstract

Altitudinal differentiation of forest vegetation is observed in different regions. Studies conducted on the western slope of the Southern Urals in the area of broadleaf and dark coniferous forests revealed the patterns of altitudinal differentiation of zonal formations of dark coniferous and broad-leaved forests. There is a correlation of each of these formations to certain elements of the relief and altitude levels. The research was carried out in the territory of the South Ural State Nature Reserve. As a result of stationary studies, indicators of phytocenotic activity of broadleaf and dark coniferous tree species and their ecotopic areals have been determined. According to the phytocenotic activity of broad-leaved species, four groups of ecotopesclimatopoids-are distinguished: mesothermal, microthermal, nano-thermal and cryotermal. Microclimatic parameters of ecotopes are determined by instrumental studies. It is established that mesothermal climatopia occupied by associations of unmoral broad-leaved forests are characterized by maximum heat supply for the given region, the greatest duration of the growing season. Nanothermal and cryothermal climatopoies occupied by associations of boreal dark coniferous forests are characterized by lower heat supply and shorter vegetation periods. Based on the results of the research, conclusions were drawn about the causes of high-altitude differentiation of zonal forest formations and the factors responsible for it. It is assumed that the altitudinal differentiation of formations of dark coniferous and broadleaf forests is due to two main causes. The first of these determines the overall spatial differentiation of formations. It is expressed in the manifestation of stenotopic broadleaf species of trees. Due to the increased requirements of broadleaf species for thermal resources, they dominate in the warmest ecotopes. The second cause, which directly determines the high-altitude differentiation of formations, is related to the altitudinal differentiation of microclimatic parameters in the conditions of mountain relief and is caused by a vertical temperature gradient. Due to temperature inversions, the temperature gradient to a certain height is negative, above which it acquires a normal character. At a certain altitude, a so-called «warm belt» is formed, with which habitats of broad-leaved forests are associated. The full height spectrum of formations, which is expressed on the slopes of high mountains, has 5 levels, a truncated spectrum characteristic of low mountains – 3 levels.