Methanotrophic functional traits are associated with soil methane uptake across a tree species richness gradient in subtropical forests

The rapid loss of plant diversity poses a serious threat to forest ecosystem functions, including soil methane (CH 4 ) uptake. However, the mechanisms involved in the effect of plant diversity on CH 4 oxidation capacity remain poorly understood. To clarify the pathways through which plant diversity regulates soil CH 4 oxidation capacity, we compiled published CH 4 oxidation potentials and pmoA gene abundances (a functional biomarker for methanotrophs) from various afforestation sites. Our results show that increased plant diversity significantly enhances both soil CH 4 oxidation potentials and pmoA gene abundance in forest soils. To further investigate the underlying mechanisms, we characterized methanotrophic community composition in a large-scale forest biodiversity-ecosystem functioning (BEF) experiment conducted in subtropical China. Consistent with the global meta-analysis, the BEF experiment demonstrated that higher tree diversity increased soil CH 4 uptake and oxidation potential, accompanied by more diverse and complex methanotrophic communities. CH 4 uptake was more strongly associated with methanotrophic functional traits (i.e. diversity and complexity of the methanotrophic community) than with measured soil physicochemical properties. Our findings highlight associations between methanotrophic functional traits and forest soil CH 4 uptake under changing plant diversity, suggesting that incorporating these functional traits into soil CH 4 process models would improve the predictive accuracy of global terrestrial CH 4 uptake, especially in the context of biodiversity loss.