https://doi.org/10.1016/j.soilbio.2025.110038

Atmospheric methane (CH4) uptake by arctic soils is widespread in dry tundra ecosystems. However, the environmental controls regulating CH4 uptake are poorly understood, particularly such as soil nutrient availability or microbial community composition. Here, we analyzed the relative abundance and community structure of functional gene markers associated with CH4 and mineral nitrogen (N) cycling in two contrasting tundra types in the Western Canadian Arctic using a targeted metagenomics approach. Microbial data were compared to soil properties, macro- and micronutrient concentrations, and CH4 fluxes during an entire growing season (May–August). We find that soil pH was the most important control on gene distribution between the studied microsites. Methanotrophs associated with the upland soil cluster α (USCα) dominated in polygonal tundra (low pH), while USCγ dominated in upland tundra (high pH). Methane uptake rates ranged from −15 to −27 μg CH4–C m−2 h−1 (growing season mean) and increased with higher relative abundances of USCα and USCγ. Although CH4 uptake rates were similar between microsites, our microbial data indicate different mechanisms to cope with N limitation in these nutrient-limited tundra environments: upland tundra was characterized by genes involved in denitrification and N retention, while polygonal tundra contained genes associated with biological N fixation. Our study highlights the need for an integrated view on interactions between CH4 oxidation and N availability for methanotrophs in arctic tundra soils.

https://doi.org/10.1016/j.soilbio.2025.110038
https://www.sciencedirect.com/science/article/pii/S0038071725003323