Soil Microbial Biomass and Functional Diversity of Microbial Communities in Native and Arable Soils of the Belogor'e Reserve

Microbial biomass and functional diversity of soil microbial communities in forest soils of the Belogor'e Nature Reserve and in arable soils formed under similar geomorphologic and lithological conditions were determined. We have analyzed the content of carbon of total microbial biomass (C-TMB), of the biomass of living microorganisms by the content of soil phospholipids (C-PL.), and of biomass of microbial cells capable of glucose assimilation (C-SIR). The respiratory response of the soil microbial community to the introduction of different groups of organic compounds-inductors (amino acids and carboxylic acids) was assessed by the method of multisubstrate testing (MST). It is shown that anthropogenic transformation of natural ecosystems results in a decrease in the total microbial biomass, biomass of living cells, and cells that give a respiratory response to glucose. The functional diversity of microbial communities in soils in natural and transformed ecosystems significantly differs. Soil plowing has resulted in a significant decrease in the ability of the soil microbial community to assimilate low-molecular organic compounds. This is most typical for amino acids: arginine, alanine, and glycine (a 2.7-, 5.4-, and 7.1-time decrease, respectively, as compared to native soils). Among carboxylic acids, the decrease in the respiratory response to the introduction of succinic acid is the most pronounced (8.7 times). It has been revealed that the geomorphologic position in natural ecosystems does not affect the biomass of the microbial community and its functional diversity, while the arable soils are characterized by a clear tendency to an increase in these parameters on the lower part of the slope.