Effect of Temperature on Litter Decomposition, Soil Microbial Community Structure and Biomass in a Mixed-Wood Forest in European Russia

Litter decomposition in terrestrial ecosystems has a major role in the biogeochemical cycling of biogenic elements, but initial stages of this process in temperate forest ecosystems remain poorly understood. Soil organic matter in forest ecosystems is highly sensitive to temperature rise, which makes it the most vulnerable under global warming. This article assesses the influence of aspen leaf and twig litter on the activity and quantitative characteristics of microbial communities of soils in conditions modelling climate warming. The experiments were performed with samples of grey forest soil, one of the most representative soil types of Europian Russia, from forest biocenosis in the Moscow region. Incubation of soil samples, in which crushed leaves and twigs were added at the rate of 0.5% by weight, was carried out at constant temperature of 5°C, 15°C and 25°C for 28 days. CO2 emission, organic carbon and microbial biomass content, and number of ribosomal genes of bacteria, archaea and fungi were evaluated. The optimal temperature for decomposition of the plant litter was found to be 15°C, and both decrease and increase led to a reduction in the intensity of the degradation process. In the temperature range 5°C–15°C, application of plant residues led to significant increase in temperature sensitivity of the soil respiration process, and temperature coefficient Q10 increased from 1.75 to 3.44–3.54. At high temperatures, addition of litter stimulated the decomposition of soil organic matter. No significant changes in microbial biomass, bacteria and fungi numbers were observed. The obtained results contribute to understanding the dynamics of soil carbon and can be used in predictive models of plant litter and soil organic matter dynamics in forest biocenoses of Eurasia under climate change.