N limitation increases along a temperate forest succession: evidences from leaf stoichiometry and nutrient resorption

Abstract

AbstractForest productivity and carbon (C) sequestration largely depend on soil N and P availability. To date, however, the temporal variation of nutrient limitation along forest succession is still under debate. Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth. Here, we measured nitrogen (N) and phosphorus (P) concentrations in green leaves and leaf litter for all woody species at four stages of temperate forest succession, and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession. At the individual scale, leaf N and P concentrations had a significant increase at the end of the succession, while no change in leaf N:P ratio was detected. Nitrogen resorption efficiency (NRE) increased significantly with succession, but P resorption efficiency (PRE) first increased and then decreased. Significant increases in NRE:PRE ratios only occurred at the end of the succession. Moreover, plant N cycling was less responsive to soil nutrient than P cycling. At the community scale, we found that leaf N and P concentrations first decreased and then increased along forest succession, which were mainly affected by Shannon–Wiener index and species richness. Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height (DBH). NRE increased and was significantly influenced by species richness and DBH, while PRE was relatively stable along forest succession. Thus, the NRE:PRE ratios significantly increased, indicating that N limitation is exacerbated with the temperate forest succession. These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community. In conclusion, our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China’s temperate and boreal forests.