Fang Zhao, Yu Hailong, Li Chunhuan, Wang Bin, Jiao Feng, Huang Juying
Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in northwestern China, Yinchuan 750021, China; Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in northwestern China of Ministry of Education, Yinchuan 750021, China; School of Ecology and Environment, Ningxia University, Yinchuan 750021, China; Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China.
School of Geography and Planning, Ningxia University, Yinchuan 750021, China.
Sci Total Environ. 2023 Jun 25;879:163033. doi: 10.1016/j.scitotenv.2023.163033. Epub 2023 Mar 24.
Under ongoing global change, whether grassland ecosystems can maintain their functions and services depends largely on their stability. However, how ecosystem stability responds to increasing phosphorus (P) inputs under nitrogen (N) loading remains unclear. We conducted a 7-year field experiment to examine the influence of elevated P inputs (ranging from 0 to 16 g P m yr) on the temporal stability of aboveground net primary productivity (ANPP) under N addition of 5 g N·m·yr in a desert steppe. We found that under N loading, P addition altered plant community composition but did not significantly affect ecosystem stability. Specifically, with the increase in the P addition rate, declines in the relative ANPP of legume could be compensated for by an increase in the relative ANPP of grass and forb species, yet community ANPP and diversity remained unchanged. Notably, the stability and asynchrony of dominant species tended to decrease with increasing P addition, and a significant decrease in legume stability was observed at high P rates (>8 g P m yr). Moreover, P addition indirectly affected ecosystem stability by multiple pathways (e.g., species diversity, species asynchrony, dominant species asynchrony, and dominant species stability), as revealed by structural equation modeling results. Our results suggest that multiple mechanisms work concurrently in stabilizing the ecosystem stability of desert steppes and that increasing P inputs may not alter desert steppe ecosystem stability under future N-enriched scenarios. Our results will help improve the accuracy of vegetation dynamics assessments in arid ecosystems under future global change.
在持续的全球变化背景下，草原生态系统能否维持其功能和服务在很大程度上取决于其稳定性。然而，在氮（N）负荷下，生态系统稳定性如何响应增加的磷（P）输入仍不清楚。我们进行了一项为期7年的田间试验，以研究在荒漠草原中添加5 g N·m·yr氮的情况下，增加磷输入（范围从0到16 g P m yr）对地上净初级生产力（ANPP）时间稳定性的影响。我们发现，在氮负荷下，添加磷改变了植物群落组成，但对生态系统稳定性没有显著影响。具体而言，随着磷添加速率的增加，豆科植物相对ANPP的下降可被禾本科和杂类草物种相对ANPP的增加所补偿，但群落ANPP和多样性保持不变。值得注意的是，优势种的稳定性和异步性倾向于随着磷添加量的增加而降低，并且在高磷水平（>8 g P m yr）下观察到豆科植物稳定性显著下降。此外，结构方程模型结果表明，添加磷通过多种途径（如物种多样性、物种异步性、优势种异步性和优势种稳定性）间接影响生态系统稳定性。我们的结果表明，多种机制共同作用以稳定荒漠草原的生态系统稳定性，并且在未来氮富集的情景下增加磷输入可能不会改变荒漠草原生态系统稳定性。我们的结果将有助于提高未来全球变化下干旱生态系统中植被动态评估的准确性。
