Nitrogen Fertilization Increases Litter Production and Nutrient Resorption Efficiency of Castanopsis eyrei In a Subtropical Forest, China

Abstract:

Anthropogenic activities has enhanced nitrogen (N) deposition globally, decoupling the biogeochemical cycles and exhibiting a profound influences on carbon sequestration across terrestrial ecosystems. The responses of plant productivity and nutrient cycling to nitrogen deposition have been widely reported in forests across Euro-America, but with little evidence from subtropical forest ecosystem across China. Here we conducted a nitrogen fertilization experiment in a nature subtropical forest in southeast China for more than four years, and investigated the induced changes in litter production, leaf N and P concentrations and resorption efficiency of Castanopsis eyrei, as the dominate species in most subtropical evergreen forests in China. Results showed that N fertilization increased litter production, which performed a concurrent seasonal pattern with peak defoliation in spring and autumn. N fertilization significantly increased N and P concentrations in green and senesced leaves, and the leaf N and P resorption efficiencies. In contrast to the predominant results across temperate and tropical ecosystems, our findings reveal a distinguishable pattern of resorption efficiencies in respond to nutrient changes, and highlight that regional characteristic and spatial heterogeneity should be considered when predicting future impacts of N deposition on plant growth and nutrient cycling.