Tree functional group mediates the effects of nutrient addition on soil nutrients and fungal communities beneath decomposing wood

Background: Deadwood contains a large reservoir of carbon and nutrients in forest ecosystems, its decomposition has considerable effects on forest soil chemistry and biota. Tree functional group and nutrient inputs both have a significant influence on wood decomposition rates. However, little is known about how these factors interactively influence soil biogeochemistry through wood decomposition. Methods: We examined the effects of nitrogen (N) and phosphorus (P) addition on wood decomposition of different angiosperm and gymnosperm tree species in a three-year period in a subtropical forest. We explored the outcomes for the underlying soil nutrients, microbial biomass, and saprotrophic fungal communities. Result: We found that P addition, rather than N, significantly increased total C, P, as well as microbial biomass C and P concentrations in the soil beneath deadwood. These effects were particularly pronounced in the soil beneath angiosperm wood compared to gymnosperm wood, likely related to the higher decomposition rates of angiosperm wood and its sensitivity to P. Similarly, the presence and abundance of soil saprotrophic fungal communities was strongly associated with P addition, where specific fungal responses were more pronounced under angiosperm wood than gymnosperm wood. Conclusion: Our study underscores the pivotal role of tree functional group in modulating the response of soil nutrient dynamics and fungal community structure beneath decomposing wood in a subtropical forest. These insights are critical for developing predictive models of soil nutrient cycles, which can help manage forest ecosystems more effectively in the face of global environmental changes.