Abstract
In this study, leaf nitrogen (N) and phosphorus (P) stoichiometry were used as indicators of nitrogen saturation and to assess ecosystem nutrient limitations. Schima superba, a representative and widely distributed dominant evergreen broadleaf tree species of the subtropical forests in southern China, was used for this purpose. A nutrient-addition experiment and a field survey were conducted to test the responses of trees from different provenances to N deposition. The relationships between leaf N and P stoichiometry and biomass, nutrient limitation, and soil N:P were analyzed. There was a relationship between leaf N, P, N:P, soil N:P and plant dry biomass. A threshold leaf N:P ratio (16.3) divided the five provenances into different nutrient-limitation classes that were related to the soil N:P ratio or N deposition. The leaf N:P ratio provided an indication of P limitation. A higher soil P level reduced the N deposition effect on plant growth. The leaf N:P ratio of individuals from different provenances can be used as a predictor of nutrient limitation, and this was related to the soil N:P ratio.
Highlights
The nitrogen (N) and phosphorous (P) levels in plant tissues, especially in the leaves, have often been studied, and the N:P ratio is considered an important indicator of nutrient limitation within individual species as well as for the entire ecosystem[1,2,3,4,5,6,7,8]
Based on uniform levels of simulated N deposition in several provenances of this species, we found that the root system was more developed, and P absorption efficiency (PAE) was higher under N deposition, which was related to soil nutrition[24]
We inferred that there would be a relationship between biomass and the leaf N:P ratios and that changes would occur in the leaf N and P stoichiometry patterns in this species under N deposition
Summary
The nitrogen (N) and phosphorous (P) levels in plant tissues, especially in the leaves, have often been studied, and the N:P ratio is considered an important indicator of nutrient limitation within individual species as well as for the entire ecosystem[1,2,3,4,5,6,7,8]. Based on uniform levels of simulated N deposition in several provenances of this species, we found that the root system was more developed, and P absorption efficiency (PAE) was higher under N deposition, which was related to soil nutrition[24] From these results, we inferred that there would be a relationship between biomass and the leaf N:P ratios and that changes would occur in the leaf N and P stoichiometry patterns in this species under N deposition. Our objectives were to (a) compare the seedling growth, leaf N, P, and N:P ratio in S. superba from different provenances in P-limited and P-rich soil under simulated N deposition treatments; (b) determine whether seedlings from different provenances with different N and P availability exhibited the same nutrient limitation; (c) compare the N:P ratio of different forest sites (Table 1, Fig. 1) using results of (a); and (d) determine the www.nature.com/scientificreports/
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