Soil water content, carbon, and nitrogen determine the abundances of methanogens, methanotrophs, and methane emission in the Zoige alpine wetland
Purpose Alpine wetland ecosystems can contribute large amounts of methane (CH 4 ) to the atmosphere; however, their emissions vary with environmental conditions. Microbial activity is known to drive CH 4 emissions, but how environmental conditions determine microbial activity is still uncertain. Here, we seek to quantify the variability of the CH 4 flux, to detect the effects of CH 4 -related microbes on CH 4 emissions, and to study the dependency of these effects on environmental conditions. Materials and methods We measured the CH 4 flux, environmental conditions, and CH 4 -related microbial communities ( mcrA and pmoA gene abundances for methanogens and methanotrophs, respectively) under three hydrological conditions (submerged, soil–water interface, and emerged) from seven sampling sites in the Zoige alpine wetland, China. Results and discussion The CH 4 flux varied greatly from 0 to 41 mg m −2 h −1 in the Zoige alpine wetland. The methanogenic and methanotrophic abundances both showed positive correlations with CH 4 flux, while CH 4 flux increased linearly with the increase of soil water content (SWC) when SWC was above 60%. CH 4 flux and methanogenic and methanotrophic abundances maintained the high levels when soil C:N ratio was in the range of 11–24 and decreased exponentially with the increase of soil DOC:TN ratio in Zoige alpine wetland, which might result from its influence on nutrient supply for microbial decomposition process. Conclusion The results provided new insight into the effects of CH 4 -related microbes on CH 4 emission and its response to different environmental conditions and helped us to comprehend the risks of high CH 4 emissions from alpine wetlands under climatic change and anthropogenic disturbance.
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