Elevated microbial network complexity and enriched methanogens contribute to higher methanogenic potential in hollows than in hummocks in alpine meadows

BACKGROUND: Glacier foreland meadows are hotspots of methane emissions, with hollows emitting more methane than adjacent hummocks. While previous work has attributed these differences mainly to variations in nutrients and physicochemical conditions, the microbial mechanisms remain unclear. To address this gap, we compared microbial community compositions and interactions in hollows and hummocks from the foreland alpine meadows of Longxiazailongba Glacier (LXZ) and Dongkemadi Glacier (DKMD) on the central Tibetan Plateau during the melting season, using amplicon sequencing and co-occurrence network analysis. RESULTS: Our results revealed significant differences in microbial community compositions across microtopography, with soil pH being the primary influencing factor, explaining up to 10.7% of the variation in microbial communities. Furthermore, methanogens were fourfold more abundant in hollows than in hummocks, whereas methanotrophs were 1.74-fold more abundant in hummocks, indicating greater methanogenesis potential in hollows and enhanced methane oxidation in hummocks. Network analysis further revealed more nodes and edges related to methanogenesis in hollows (85 nodes and 161 edges) than in hummocks (65 nodes and 152 edges), reflecting more complex methanogenesis-related microbial association in hollows. CONCLUSIONS: Together, these findings revealed distinct microbial compositions, interactions, and methane-cycling dynamics between hollows and hummocks, providing novel insights into the biogeochemical processes in glacier foreland meadows.