Foliar nitrogen (N) or phosphorus (P) status and their stoichiometric homeostasis are integral parts of the plant nutrient economy that determines the success of plant species in environments where N or P limits plant growth. Despite growing evidence for higher predictability of stoichiometric homeostasis of N (H_N) than that of P (H_P) on plant species abundance in temperate grasslands, no previous studies explicitly examined how foliar N and P status modulate the relationships between stoichiometric homeostasis and species distribution (regional species abundance) of woody plants, especially in P-limited (sub)-tropical ecosystems. We hypothesized that species with a conservative foliar nutrient status but a higher H_P (but not H_N) would be regional abundant in P-limited forest.

We measured foliar N (LNC) and P (LPC) contents of 54 woody species, community composition and soil N and P contents across 94 forest plots in Chinese subtropical forests. Then we evaluated the species’ levels of N and P stoichiometric homeostasis and their regional abundance to test our hypotheses.

H_N and H_P significantly increased with decreasing LNC and LPC. Foliar nutrient status positively correlated with the minimum values of both soil N and P contents, but only negatively associated with the maximum value of soil P content, indicating that conservative species can occupy a wider range of soil P- than N-based nutrient niche. Meanwhile, species abundance negatively correlated with LNC and LPC, and positively correlated with H_N and H_P. However, the structure equation model analysis showed that species abundance increased with decline of LNC but not yet with increased HN. In contrast, species abundance enhanced with increased H_P and decreased LPC via H_N, rather than directly with a decline of LPC.

Synthesis. This study provides empirical evidence that species with conservative foliar nutrient status are more stable in terms of N and P stoichiometric homeostasis, and foliar N and P economy modulate species abundance distribution in different ways. Our results suggest that maintaining strong stoichiometric homeostasis of leaf P, while maintaining conservative economy of N, is a key physiochemical mechanism for shaping species abundance distribution in P-limited forests.

The dataset includes the measured data of foliar N (LNC) and P (LPC) contents of 54 woody species and soil N and P contents that the species distributed in Chinese subtropical forests. Besides we estimated the N homeostasis  (H_N) for 45 and P homeostasis  (H_P) for 36 of these species and their regional species abundance for testing how foliar N and P status and their stoichiometric homeostasis of woody plants affect regional species abundance distribution.

For additional information, please email Hang Ci or Enrong Yan (cihangcaf@163.com, eryan@des.ecnu.edu.cn).