Ectomycorrhizal trees rely on nitrogen resorption less than arbuscular mycorrhizal trees globally

Nitrogen (N) resorption is an important pathway of N conservation, contributing to a proportion of plant N requirement. However, whether the ratio of N resorption to N requirement would be affected by environmental factors, mycorrhizal types or atmospheric CO2 concentration remains unclear. Here, we conducted a meta-analysis on the impacts of environmental factors and mycorrhizal types on this ratio. We found this ratio in ectomycorrhizal (EM) trees decreased with mean annual precipitation (MAP), mean annual temperature (MAT), soil total N content (TN) and atmospheric CO2 concentration and was significantly lower than that in arbuscular mycorrhizal (AM) trees. An in situ 15N tracing experiment further confirmed this stronger reliance on N resorption for AM trees than EM trees. Our study suggests that AM and EM trees potentially have different strategies for alleviation of progressive N limitation, highlighting the necessity of incorporating plant mycorrhizal types into Earth System Models.