Heavy grazing intensifies antagonistic effects of nitrogen and phosphorus addition on the water use efficiency of grasslands in Inner Mongolia

文献类型： 外文期刊

第一作者： Xu, Xuebao

作者： Xu, Xuebao;Lv, Guangyi;Gao, Cuiping;Wang, Xinya;Zhang, Lei;Wang, Chengjie;Xu, Xuebao;Lv, Guangyi;Gao, Cuiping;Wang, Xinya;Zhang, Lei;Wang, Chengjie;Tang, Shiming;Zhang, Tongrui;Zhang, Bin;Sun, Zhaokai;Wang, Xinning;Sun, Chongzhi;Li, Yanlong;Liu, Zhenpeng;Yuan, Fengqin;Yao, Hongyun

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关键词： Water use efficiency; Stable carbon isotope; Grazing; N addition; P addition

期刊名称：ECOLOGICAL PROCESSES （ 影响因子：3.9； 五年影响因子：5.4 ）

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年卷期： 2025 年 14 卷 1 期

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收录情况： SCI

摘要： BackgroundPlant water use efficiency (WUE) is a key indicator of coupling between the carbon and water cycles in grassland ecosystems and is influenced by both grazing and nutrient availability. However, the regulatory effects of grazing intensity on plant WUE under nitrogen (N) and phosphorus (P) addition remain unclear.MethodsThis study employed stable carbon isotope techniques in a typical steppe ecosystem in Inner Mongolia, China, to investigate the effects of grazing, N and P addition, and their interactions on the foliar delta 13C values of four dominant plant species. This research aims to assess the dynamics and underlying mechanisms of grassland WUE under grazing management in the context of global change.ResultsGrazing intensity and nutrient addition significantly affected the delta 13Cleaf values. Heavy grazing increased the delta 13Cleaf values of Cleistogenes squarrosa and Carex korshinskyi but decreased those of Leymus chinensis and Stipa grandis. N addition increased delta 13Cleaf across all species, whereas P addition significantly increased delta 13Cleaf in Cleistogenes squarrosa but decreased it in the other species. A significant antagonistic interaction between N and P addition was observed, where P inhibited the positive effects of N. This antagonistic effect was amplified under heavy grazing, leading to reduced plant WUE. Structural equation modeling analysis further identified soil temperature and leaf total N as the dominant factors governing plant WUE dynamics, with both factors contributing to an increase in plant WUE.ConclusionsThis study highlights that grazing can modulate the effects of N and P addition on WUE in grasslands. Specifically, heavy grazing exacerbated the antagonistic effects of N and P addition on plant WUE, suggesting that overgrazed grasslands under N and P enrichment could face increased water limitation. In light of concurrent environmental changes, future grassland management should consider the interactive effects between grazing intensity and nutrient dynamics on plant water relations, growth and plant community composition.

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