Stability of the Orostachys steppe to pasture load in the conditions of Altai Mountains

УДК 582.715(252.5)633.2.033(571.151)

Abstract

In 2016-2018 and 2020-2021 the condition of vegetation and the features of the formation of aboveground phytomass of the petrophytic steppe with the dominance of Orostachys spinosa, located in the southeast of the Altai Republic and used as pasture mainly in the spring, late summer and autumn periods, are considered. Orostachys spinosa is one of the most cold-tolerant plants with CAM photosynthesis. The steppe with Orostachys spinosa is quite resistant to grazing, but over the years of research, signs of increasing pasture digression of the herbage, a decrease in the weight participation of steppe grasses and Artemisia frigida, and an increase in the presence of grazing-resistant Carex duriuscula and Ephedra gerardiana are noted. On the pasture, Orostachys spinosa is primarily exposed to trampling, which leads to the formation of very small rosettes of pale green color and a decrease in the number of generative shoots, while its share in the living aboveground phytomass of the community varied in different years from 20 to 71 %. During dry summer periods, an increase in the mass and projective cover of this species was observed, and the most severe suppression of Orostachys spinosa is facilitated by a combination of intensive grazing and wet weather conditions during the growing season.