A Comparative Assessment of the Biological Properties of Soils in the Cultural and Native Cenoses of the Central Caucasus (Using the Example of the Terskii Variant of Altitudinal Zonality in Kabardino-Balkaria)

The biological properties of the most widespread automorphic and hydromorphic soils of cultural and native cenoses in the Terskii variant of the altitudinal zonality (Kabardino-Balkaria) are compared. The data on the humus reserves in the 0- to 20-cm soil layer and those on the carbon content in the microbial biomass calculated on the basis of the results of substrate-induced respiration measurements are presented. The share of carbon in the microbial biomass of the total organic carbon in the soils was determined. Long-term (more than 70 years) farming on the studied soils significantly changed their biological properties. The humus content and its reserves became lower by 25-40%. The physiological activity of the microbial biomass in the cultural soils decreased by more than 60%. Presently, the soils of the cultural cenoses function as an entire natural system, but at a lower level of fertility; the loss of more than 30% of the bioorganic potential (the critical threshold of soil system stability) indicates the disturbance of soil ecological functions, their stability, and the capability of self-restoration.