Wood taxonomic division and nutrient type jointly influence wood decomposition responses to nutrient additions in a subtropical forest

Background Wood decomposition is a critical process in forest ecosystems, influencing vegetation productivity, species composition and carbon (C) storage. Wood decomposition rates are strongly controlled by high contents of recalcitrant components (e.g., lignin) and low nutrient concentrations (e.g., nitrogen [N] and phosphorus [P]), which vary systematically between major taxonomic divisions (i.e., angiosperms and gymnosperms). Under climate change, external nutrient inputs may increase wood nutrient availability and decomposition rate. However, the interactive mechanisms by which wood taxonomic division and nutrient addition affect wood decomposition remain poorly understood. Methods We examined the responses of wood decomposition rates to N and P additions between angiosperms and gymnosperms in a subtropical forest. Results Nutrient additions significantly accelerated decomposition by elevating wood N and P concentrations and decreasing the activities of N- and P-acquiring enzymes. The magnitude of this acceleration varied with types of nutrient addition and wood taxonomic division. Specifically, P addition stimulated decomposition (+100%) more than N addition (+43%), suggesting stronger microbial P limitation during wood decomposition. Further, gymnosperms (+138%) were more responsive to nutrient addition than angiosperms (+46%). This indicated that the lower initial substrate quality and higher C concentration in gymnosperm wood may result in a higher nutrient sensitivity of wood decomposition. Conclusion Our findings highlight that nutrient type and wood taxonomic division jointly influence wood decomposition responses to nutrient additions. Givern that the range of gymnosperms tree species are expanding under forest management practices, this expansion will accelerate dead wood decomposition and reshape C cycling in subtropical forests.