Mycorrhizal Symbiosis Alleviates Nitrogen‐Induced Phosphorus Limitation in Terrestrial Ecosystems

Abstract Anthropogenic nitrogen (N) deposition is increasing globally and has been documented to enhance soil carbon (C) storage; however, its concurrent effects on ecosystem phosphorus (P) limitation remain unclear. By conducting a meta‐analysis of 360 observations from 63 field N addition experiments in forest, grassland, and cropland ecosystems, we systematically assessed the consequence of terrestrial ecosystem P limitation under increasing N deposition. Our results demonstrate that N deposition significantly increased soil N:P, plant C:P and N:P ratios by 12%–29%, suggesting intensified P limitation across terrestrial ecosystems. Critically, N deposition induced differential responses between plants and soil microorganisms, with plants experiencing more severe P limitation. Notably, ectomycorrhizal (ECM) symbiosis is useful for alleviating P limitation in plants, whereas arbuscular mycorrhizal (AM) symbiosis is more useful for microorganisms in this context than for plants. Furthermore, the magnitude of N‐induced P limitation varied substantially across ecosystems, with particularly strong effects observed in croplands compared with forests and grasslands. This discrepancy may be attributed to the higher dependence of cultivated crops on P for achieving rapid growth under intensive breeding conditions. The response of C:P and N:P ratios in soils and plants negatively correlated with soil pH changes but was significant only in AM‐dominated ecosystems. This suggests that the former is more sensitive to N‐induced pH shifts than ECM‐associated ecosystems. Our findings demonstrate that mycorrhizal types mediate the ecosystem trajectory of N‐induced P limitation, highlighting the critical role of plant‐microbial interactions in mitigating the impacts of increasing N deposition and climate change.