How do water table drawdown, duration of drainage, and warming influence greenhouse gas emissions from drained peatlands of the Zoige Plateau?
Dan Xue, Huai Chen, Wei Zhan, Xinya Huang, Yixin He, Chuan Zhao, Dan Zhu, Jianliang Liu
Abstract
Abstract Alpine peatlands on the Qinghai‐Tibet Plateau are an important soil carbon pool and are extremely sensitive to global change. Duration of drainage and water table drawdown accelerate peatland degradation because the soil changes from an anaerobic to aerobic environment, and climate warming exacerbates this shift. The objective of the present study was to evaluate the effects of drainage on microbial characteristics and greenhouse gas (GHG) emissions, as well as identify the factors mediating those effects. This study also analyzed whether warming increases the variability of GHG emissions. Watertable drawdown exerted greater influence on microbial communities than duration of drainage did. Watertable drawdown significantly increased the relative abundances of Proteobacteria, Acidobacteria, Actinobacteria, and Basidiomycota, and changes in soil microbiota correlated with differences in GHG emissions across three water‐table treatments. Longer drainage was associated with lower GHG emission; watertable drawdown decreased emissions of CO 2 and CH 4 , but increased emission of N 2 O. In addition, high temperature increased CO 2 emission by 75% and N 2 O emission by 42%, without significantly affecting CH 4 emission. Structural equation modelling showed that microbes, especially prokaryotes ( r = 0.79, p < 0.05 for all), were the primary factor affecting GHG emissions from drained peatlands. Overall, this study indicates that the watertable exerts a greater effect on GHG emissions than duration of drainage, and that warming increases variability of GHG emissions.