Hydrology drives spatiotemporal patterns of methane microbial communities and methane emissions in a sub-alpine peatland, Central China

Methanogens and methanotrophs are important in regulating the peatland carbon cycle. The influence of hydrology on microbiota in different peatlands has been globally documented; however, the hydrological impact on methane-related microbial communities and methane (CH4) emission remains underexplored in sub-alpine peatlands. Here, seasonal methanogenic and methanotrophic communities, as well as CH4 emission, were determined at two sites with different water table levels from the Dajiuhu peatland, the largest intact sub-alpine peatland. Methane-related microbial communities varied with water table. A higher methanogenic and lower methanotrophic α-diversity were unveiled in samples with low water table (LWT), a reverse pattern was observed in high water table (HWT). Hydrogenotrophic methanogens dominated in samples with LWT, whereas hydrogenotrophic and aceticlastic methanogens dominated with HWT. Type II methanotrophs were predominant at both sites. Samples with HWT had higher gene copy numbers of methanogens (mcrA) and methanotrophs (pmoA) than those with LWT. Along the peat profile, methanogens and type II methanotrophs were enriched in samples at the depth of 10 - 15 cm and their abundances decreased toward deeper layers. Both type Ia and Ib methanotrophs were abundant in surface samples (0 - 5 cm). The HWT co-occurrence networks of methanogen and methanotroph were more stable and complex in contrast to those in LWT. Soil temperature was an important driver of seasonal variations in CH4 emission at the LWT sites (0.03 - 1.61 mg m−2 h−1 for bare peat and 0.06 - 4.08 mg m−2 h−1 for peat covered with Sphagnum palustre) and HWT sites (0.25 - 0.78 mg m−2 h−1 for bare peat and 0.42 - 9.60 mg m−2 h−1 for peat covered S. palustre). The water table and vegetation affected the pattern of seasonal CH4 emission. These results provide new insights in understanding the effect of hydrology on microbial functional groups and CH4 emission within sub-alpine peatlands.