Assessment of Changes in the Biological Activity of Mountain Meadow-Steppe Soils of Pastures of Different Stages of Digression in the Central Caucasus

Abstract

The indicators of biological activity (humus content and reserves, microbial biomass carbon content and reserves, activity of hydrolase and oxidoreductase class enzymes) in the upper horizons (0–10 cm) of mountain meadow-steppe soils of the Central Caucasus (Kabardino-Balkaria) were determined at different stages of pasture digression (D1, D2, D3). It was found that the values of controlled soil parameters in conditions of weakly (D1) and moderately disturbed (D2) meadow phytocenoses did not significantly differ (t 1.97; P 0.05). Statistically significant decreases (t 2.95; P 0.05) in biological parameters were revealed in soils of severely disturbed meadow steppes (D3) compared with less damaged meadows (D1 and D2). Based on the totality of the studied indicators of biological activity, an integral indicator of the ecological and biological state of soils (IIEBSS) is calculated, reflecting the overall level of biological activity of the studied soils at different stages of digression of meadow-steppe communities. There was a decrease in the IIEBSS of moderately grazed (D2) and overgrazed (D3) meadows relative to the values of the conditional standard (D1) by 11and 45%, respectively. The obtained results of the biological state of mountain meadow-steppe soils are used for monitoring studies aimed at assessing the degree of change in the soil and vegetation cover of mountain pasture ecosystems.