Phosphorus addition diminishes the negative effect of nitrogen addition on methane sink in subtropical forest soils

Increased global nitrogen (N) and phosphorus (P) inputs caused by human activities can significantly impact methane (CH₄) uptake in terrestrial ecosystems. Forest soils, as the largest CH₄ sink among terrestrial ecosystems, play a crucial role in mitigating global warming. However, the effects of long-term N and P additions on CH₄ sink and the associated microbial mechanisms in subtropical forest soils remain unclear. To address this knowledge gap, we conducted a one-year in-situ field observations of soil CH₄ fluxes in a long-term N and P addition experimental platform in subtropical forest, focusing on community structure and abundance of methanotrophs. Our findings revealed that long-term N addition significantly reduced the forest CH₄ sink, which was attributed mostly to a decrease in the CH₄ oxidation potential and the abundance of methanotrophs. Conversely, long-term P addition significantly enhanced the forest CH₄ sink due to an increase in the CH₄ oxidation potential and abundance of methanotrophs. Furthermore, we found a significant interactive effect of long-term N and P additions on forest CH₄ sink, with P mitigating the inhibitory effects of N addition on soil CH₄ sink. Overall, our results underscore the importance of understanding the interactive effects of long-term N and P additions on CH₄ sink in forests. This knowledge will enhance the accuracy of model predictions regarding atmospheric CH₄ dynamics amidst future global changes in N and P inputs.