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

Abstract

Abstract 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.