Soil Indicators of Pasture Digression in Different Types of Subalpine Meadows in the Central Caucasus

The article presents a comparative analysis of soil parameters in steppe, mesophytic and wet subalpine meadows at various digression stages (DS) in the Central Caucasus (within the Kabardino-Balkar Republic). Despite the genetic proximity, soils of different meadow types reacted differently to grazing. Consequently, soil indicators of pasture digression varied for each grassland type. Soils of steppe subalpine meadowswere the most dynamic, displaying negative changes even under moderate grazing load at DS2 compared to the least disturbed meadowsat DS1(0). In the upper soil horizons (0–20 cm) at the DS2 the bulk density increased by 25%, total soil carbon content C_org decreased by 36%, and the carbon content of microbial biomass C_mic decreased by 39% (t > 2.3; p < 0.03). At DS3 (severe degradation stage), all studied soil parameters of steppe meadows changed significantly (t > 2.9; p < 0.006), including basal respiration rate BR of soil microorganisms. It was established that the soil parameters did not change significantly. Under moderate controlled grazing (DS2) in mesophytic and wet subalpine meadows and the soil system remained stable. The most sustainable indicators of the severe grazing load (DS3) for mesophytic grasslands were C_mic with a 28% decrease (t > 2.4; p < 0.02), and the C_mic/C_org ratio. BR, C_mic and C_org, C_mic/C_org ratio were significantly reduced (t > 2.4; p < 0.03) at DS3 of wet subalpine meadows.