| 摘 要： |
Both climate warming and increasing nitrogen deposition promote the availability of nitrogen (N) and phosphorus (P) to plants in soil, which may affect ecosystem structure and function. However, studies on the effects of nutrient enrichment on ecosystems have mostly focused on N rather than P, especially in high-altitude areas where N limits plant growth, which hinders the prediction of ecosystem changes under future climate conditions. Using a 5-year experiment at an alpine meadow, we quantified the aboveground net primary production (ANPP) stability under three N levels and four P levels, including the interaction of different N and P levels. We also tested possible drivers of the ANPP stability, including plant species richness, asynchrony, dominance, and plant functional group stability. Finally, we used structural equation models to explore how different drivers affect ANPP stability. Results showed: (a) Plant growth in the alpine meadow was limited by soil available-N but not -P, and N enrichment induced P limitation on plant growth. (b) P enrichment promoted species richness, asynchrony and dominant species stability, and consequently increased the ANPP stability. (c) Species asynchrony and dominant species stability were the key mechanisms driving the variation of ANPP stability. These findings highlight the importance of understanding the balance of N and P effects on ecosystem structure and function in order to better predict the impacts of global change on ecosystem stability. |
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