Extraradical hyphae alleviate nitrogen deposition‐induced phosphorus deficiency in ectomycorrhiza‐dominated forests

Abstract

Summary The continuous imbalance between nitrogen (N) and phosphorus (P) deposition is expected to shift many ecosystems from N‐ to P limitation. Extraradical hyphae of ectomycorrhizal (ECM) fungi play important roles in plant nutrient acquisition under nutrient deficiency. However, whether and how ECM hyphae enhance soil P availability to alleviate N‐induced P deficiency remains unclear. We investigated the impacts of ECM hyphae on transformations among different soil P fractions and underlying mechanisms under N deposition in two ECM‐dominated forests. Ectomycorrhizal hyphae enhanced soil P availability under N addition by stimulating mineralization of organic P (Po) and desorption and solubilization of secondary mineral P, as indicated by N‐induced increase in positive hyphal effect on plant‐available P pool and negative hyphal effects on Po and secondary mineral P pools. Moreover, ECM hyphae increased soil phosphatase activity and abundance of microbial genes associated with Po mineralization and inorganic P solubilization, while decreasing concentrations of Fe/Al oxides. Our results suggest that ECM hyphae can alleviate N‐induced P deficiency in ECM‐dominated forests by regulating interactions between microbial and abiotic factors involved in soil P transformations. This advances our understanding of plant acclimation strategies via mediating plant–mycorrhiza interactions to sustain forest production and functional stability under changing environments.