Variation in leaf phosphorus fractions reflects plant adaptations and distribution in low‐phosphorus tropical forests

Abstract Tropical forests are generally characterized by high species diversity and low soil phosphorus (P) availability. Although tropical plants have evolved adaptations to low soil P availability, we know relatively little about the strategies of different groups of species to efficiently use P, or how these strategies might shape their distributions. We compared the performance of 16 co‐occurring species in tropical forests in South China under two soil P regimes. We divided these species into three groups: exotic species, which are not native to South China; eurytopic native species, which occur in both P‐limited and P‐richer habitats; stenotopic native species, which only occur in low‐P habitats. We assessed their growth rates, foliar functional traits and foliar P fractions under experimentally manipulated soil P availability (Control vs. +P). Exotic species exhibited greater plasticity in allocation of leaf P fractions than native species. Compared with native species, exotic species allocated more P to inorganic‐P than to ester‐P and nucleic‐P in P‐enriched soil, while they allocated less P to inorganic‐P and ester‐P in low‐P soil. Eurytopic native species responded inconsistently to P addition, indicating that eurytopic native species may employ various strategies to cope with low P availability, whereas stenotopic native species showed only minor changes in leaf P allocation with P fertilization. We distinguished two strategies for plant adaptation to low soil P availability: (1) a P‐plastic strategy exhibited by exotic species, in which P leaf and leaf P‐fraction allocation patterns changed substantially with soil P enrichment; (2) a P‐conservative strategy exhibited by stenotopic native species, in which P leaf and leaf P‐fraction allocation patterns changed only slightly with soil P enrichment. In conclusion, the distinct strategies exhibited by plants in low‐P habitats may determine their distribution and coexistence in tropical regions. Read the free Plain Language Summary for this article on the Journal blog.