DYNAMICS OF <i>THERMOPSIS MONGOLICA</i> (FABACEAE) COENOPOPULATIONS IN THE STEPPES OF THE ALTAI REPUBLIC

Abstract

Studies of Thermopsis mongolica, a poisonous perennial herbaceous plant with a long rhizome, which spreads rapidly in grazing meadow and steppe phytocenoses of the Altai Republic, were conducted. In permanently grazed pastures, the thermopsis is not eaten by cattle and, with reduced competition from other species, quickly spreads and invades the territory due to a large number of growing rhizomes. Due to vegetative propagation, the main maximum in T. mongolica cenopopulations is represented by virginal ramets, the second one y middle-aged or old generative ramets. With increasing anthropogenic pressure, the share of virginal ramets and the cenopopulation density increase. In the communities disturbed by cattle grazing with the stage III of pasture digression, thermopsis co-dominates and makes an aspect in the herbaceous layer. In such cenopopulations, the thermopsis density increases from 24.8 to 131.2 ramets per m2. Generative shoots in this case reach the maximum morphometric parameters, power and productivity. Continuous grazing until complete failure (stage IV) leads to rapid aging of T. mongolica plants and accumulation of old ramets. In the ontogenetic spectra, the second maximum is shifted to the ramets of the postgenerative period. Due to constant trampling and soil compaction, the density of T. mongolica decreases to 6.5–4.6 ramets per m2. Thus, the anthropogenic load, if not destructive, leads to weakening of interspecific competition, which enables T. mongolica to increase rapidly the organismal and population indices and to realize its reactive properties.