Functional activity of soil microbial communities in post-fire pine stands of Tolyatti, Samara oblast

The state of microbial communities in gray-humus soils (Eutric Fluvic Arenosols (Ochric)) of pine stands in the city of Tolyatti after forest fires of 2010 is analyzed. It is shown that fires exert negative effects on the structure and metabolic activity of microbial communities in the postpyrogenic soils. The content of the carbon of microbial biomass and the intensity of microbial respiration in the upper organic horizons of the post-fire plots decrease by 6.5 and 3.4 times, respectively, in comparison with those in the soils of background plots. However, the fire has not affected the studied microbiological parameters of the soils at the depths of more than 10 cm. The maximum content of the carbon of microbial biomass carbon and the maximum intensity of microbial respiration have been found in the subsurface AY2 and АС horizons two–three years the fire. An increase in the microbial metabolic quotient (the ratio of soil respiration to microbial biomass) attests to the disturbance of the ecophysiological state of soil microbial communities after the pyrogenic impact.