Mr Jie Zhou1, Prof. Dr Huadong Zang1
1College of Agronomy and Biotechnology, China Agricultural University, Beijing, China
Microbial activity has been highlighted as one of the main unknown factors controlling the soil carbon (C) cycling in response to global warming. How the responses of microbial parameters (e.g. community structure and function) to increasing temperature are not well understood. Here, the classical physiological approaches based on microbial growth kinetics and affinity to the labile substrate was used to show the shift in functional properties of the soil microbial community under long-term soil warming. Kinetic parameters of substrate-induced growth respiration (SIGR) and the dynamics of enzyme (involved in C, N, and P cycling) kinetics after available substrates input in response to temperature elevation (ambient, ambient +1.6°C, and ambient +3.2°C) were monitored. We find that increasing temperature reduces total microbial biomass C (MBC) but increases growing microbial biomass (GMB) and specific growth rate (μ) of soil microorganisms. These results indicate that warming altered the ecological strategy of the soil microbial community, i.e. a shift towards to the fast-growing r-strategists, which probably due to enhanced substrates and nitrogen availability with warming. And consequently induced a shift in enzymatic systems, as indicated by a increased enzyme kinetic parameters Vmax and Km. Although MBC decreased with temperature, long-term warming increased the specific enzyme activities, indicating the allocation of resources to enzyme production rather maintenance growth. In conclusion, such shift to the r-selected microorganisms indicates acceleration of available C mineralization in soil, supported by the higher extracellular enzyme activities and basal respiration, which counterbalance the additional C input by roots in a future warming environment.
Biography: I am a PhD student, who want to know how mycorrhiza lfungi and warming affect soil organic matter decomposition.