• Soil type integrates climate-nutrient gradients filter methanotroph at a continental scale. • Stochastic processes dominate methanotroph assembly and increasing with MAT. • Methanotrophs serve as keystone species in networks, reshaped by soil-specific conditions. • Reveal a mechanistic from soil type to microbial ecology to ecosystem function. Microbially mediated methane (CH 4 ) oxidation affects global climate change, with paddy soils representing a major mitigation hotspot. Soil type fundamentally shapes the microbial communities, its continental-scale role in regulating methanotrophic assembly and CH 4 oxidation potential in paddies remains unclear. This study investigated methanotrophs across three major paddy soils (black, yellow, and red soils) along a broad climatic gradient in China. We found that CH 4 oxidation potential and pmoA gene abundance were significantly higher in black soils, which were dominated by Type I methanotrophs ( Methylobacter ), contrasting with Type II dominated ( Methylocystis ) yellow and red soils. This biogeographic pattern was primarily driven by the synergistic effect of climate (mean annual temperature, MAT) and soil nutrients (carbon and nitrogen). A striking finding was that the anaerobic methanotroph Methylomirabilis (NC10) emerged as a keystone specifically in yellow soil. Stochastic processes dominated the assembly of methanotrophs, with stochasticity increasing from black to red soils as the MAT rises. Furthermore, function prediction indicated that the abundance of key functional enzymes for CH 4 oxidation (e.g., pMMO and sMMO) was highest in black soils, consistent with the measured oxidation potentials. Our study demonstrates that soil type integrates climate-nutrient interactions to modulate CH 4 oxidation by filtering methanotroph communities, which subsequently alter assembly processes and network keystone species. Therefore, integrating these soil-specific microbial mechanisms is essential for predicting CH 4 feedbacks.
Yin et al. (Thu,) studied this question.