Warming and grazing effects on soil C and N cycling and microbial communities in alpine grasslands of the Tibet Plateau
Uncertainty about the effects of warming and grazing on soil C, N, and P dynamics, microbial communities species composition, and aboveground net primary production limits our ability to predict how global carbon sequestration will vary under future warming with grazing in alpine regions. Through a controlled asymmetrical warming (1.2/1.7°C during daytime/nighttime) with a grazing experiment in an alpine meadow on the Tibet Plateau, I investigated how combined warming and grazing affected soil C, N, and P pools, microbial abundance, net N mineralization. Findings suggest that soil N availability does not determine ANPP under simulated warming and that heavy grazing rather than warming causes degradation of the alpine meadows.
Soil organic matter turnover and microbial activity in dryland agricultural systems in Western Australia
Spatial and temporal patterns of water availability are the fundamental drivers of biological processes in arid and semi-arid ecosystems. Microorganisms determine if fresh C input is converted into stable soil organic matter or lost as CO2. I investigated the response of microbial biomass and respiration to organic matter amendments and how wetting patterns (frequency and intensity) and nutrient additions altered microbial biomass and CO2-C loss from a semi-arid soil. Findings suggest increasing plant residues are not able to build microbial biomass while smaller more frequent summer rainfall may decrease CO2 emissions compared to infrequent larger events; and enhance microbial C use efficiency where sufficient background SOM and nutrients are available.