Changes in the ratio of plants with different mycorrhizal status in the course of pasture digression in the Southern Ural steppes

Trends in the proportions of plants differently interacting with mycorrhizal fungi in the course of pasture digression have been analyzed in the steppe zone of the Southern Urals. Estimates of species richness and abundance of plant groups with different mycorrhizal status have been obtained by comparing original data on the structure of phytocenoses with published data on the ability of plant species to form mycorrhizae. It has been shown that the proportions and abundance of obligate mycorrhizal species decrease significantly in the course of digression, with consequent increase in those of species less dependent on or independent of symbiosis with fungi, i.e., facultative mycorrhizal or obligate nonmycorrhizal plants.