Soil N and P nutrient metabolism affected by fungal community in larch plantation

Introduction The time-response mechanism of soil nitrogen (N) and phosphorus (P) nutrients across different stand ages remains intricate and inadequately quantified, particularly unclear is the effects of rhizosphere soil microbial communities, which serve as crucial drivers on soil N and P nutrients. This study delved into the effects of soil fungal community on the shifts of soil physicochemical properties and their correlations between N-P distribution within rhizosphere of Larix kaempferi (Japanese larch) with different tree stands. Methods This study investigated the responses of soil nitrogen (N) and phosphorus (P) along a stand age gradient (young: <20 years; mid-aged: 20–30 years; near-mature: 30–40 years; mature: >40 years) in Larix kaempferi forests, with a focus on the associations between rhizosphere microbial communities and soil nutrient dynamics. By covering key developmental stages of forest succession, we examined age-related changes in rhizosphere soil N and P concentrations, soil physicochemical properties, and fungal community structure. Results The results showed that fungal community structure gradually diversified from young to near-mature forests and became more stable in the mature forest stage. Differences in forest age were associated with changes in the availability and distribution of soil N and P nutrients, accompanied by shifts in the relative abundance of microbial functional genes related to N and P cycling. In particular, the abundance of P cycling–related functional genes showed patterns consistent with soil N and P variations, while N fixation–related functional genes exhibited the highest abundance in the middle-aged forest stage. Discussion Overall, variations in stand development along the forest age gradient were closely linked to changes in soil nutrient distribution and rhizosphere microbial biomass, highlighting the potential role of rhizosphere microbial communities in soil N and P cycling in larch plantation ecosystems.