Plastic responses of below-ground foraging traits to soil phosphorus-rich patches across 17 coexisting AM tree species in a subtropical forest

Below-ground plastic responses to soil nutrient 'hot-spots' form a key nutrient foraging strategy of plants coexisting in natural ecosystems. However, it is unclear how plant species differ in these below-ground plastic responses and how they covary.Plastic responses to soil phosphorus (P)-rich patches of absorptive root, mycorrhizal, and exudation traits of 17 coexisting arbuscular mycorrhizal (AM) tree species in a subtropical evergreen broad-leaved forest were investigated using a root bag method.There was considerable variation and heterogeneity in species-specific responses to P-rich patches. Negative log response ratios usually occurred for high-cost traits and positive log response ratios for low-cost traits. There were trade-offs in the plastic responses between root acid phosphatase activity and extraradical hyphal length, which were unaffected by phylogeny, and between root acid phosphatase activity and specific root length. Thicker-rooted species responded to P-rich patches more through root exudation plasticity than mycorrhizal plasticity. Thinner-rooted species relied more on mycorrhizal plasticity.Synthesis. Our results revealed diverse P foraging strategies comprising different combinations of plastic adjustments in absorptive root, mycorrhizal, and exudation traits among coexisting AM tree species, which suggest the potential for complementary exploitation of different soil P sources.