Effect of Reforestation on Microbiological Activity of Postagrogenic Soils in European Russia

We have studied the microbiological activity of postagrogenic soddy–podzolic, gray, and dark gray forest soils representing succession stages of natural reforestation on former agricultural lands in various forest zones. The chosen succession chronoseries of postagrogenic soils are uniform and include arable soil, abandoned lands of various ages, and forest cenoses. The content of organic carbon (C_org) and total nitrogen (N), pH, water holding capacity (WHC), basal respiration (V_basal), microbial biomass carbon (C_mic), and ecophysiological parameters of the status of microbial communities (metabolic coefficient qCO₂; the C_mic: C_org ratio, and specific rate of basal respiration calculated as the V_basal: C_org ratio) are determined in mixed soil samples taken from 0–10 and 10–20 cm layers. It has been revealed that the transformation of arable soils into abandoned lands constantly occupied by meadow or forest vegetation usually results in the progressive accumulation of organic carbon in the 0–10-cm layer. This causes more active soil respiration and a significant increase in the pool of microbial carbon. Parallel to this, the processes of podzol formation upon the development of forest vegetation result in a pronounced increase in acidity in the 10–20 cm layer, which causes a decrease in V_basal and C_mic in soils of forest cenosis. For all the studied chronoseries of postagrogenic soils, the correlation between microbiological parameters (V_basal and C_mic) and the general soil properties (C_org, N, and WHC) is the closest. The following factors (in decreasing order) exert effect on the dynamics of all the studied properties at postagrogenic evolution: forest zone/soil type > age of abandoned land ˜ depth in the arable layer.