Grazing intensity significantly changes the C : N : P stoichiometry in grassland ecosystems
Grazing intensity significantly changes the C : N : P stoichiometry in grassland ecosystems
复制标题
放牧强度显着改变草地生态系统中的C:N:P化学计量
DOI：
10.1111/geb.13028
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发表时间：
2019-11-19
影响因子：
6.4
通讯作者：
Zhou, Xuhui
中科院分区：
文献类型：
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作者：
He, Miao;Zhou, Guiyao;Zhou, Xuhui
放牧可以改变草地的碳(C)、氮(N)和磷(P)循环，从而影响草地的C：N：P化学计量比。本研究旨在研究放牧对草地生态系统C：N：P化学计量学影响的机制，重点是地下过程及其与地上植被特性的联系。全球时间段1900-2018草地生态系统研究的主要分类群。方法在129篇文献的基础上进行荟萃分析，综合放牧对草地生态系统叶、茎、凋落物、根、微生物生物量和土壤的C：N：P化学计量学的影响。结果放牧显著影响草原生态系统的C、N、P库，进而影响草原生态系统的C：N：P化学计量学。放牧对C：N：P化学计量比的影响随放牧强度的不同而变化较大。具体来说，重度放牧降低了除凋落物N：P和根系C：N以外的所有C：N：P化学计量比，而轻度和中度放牧产生的负面或正面影响较小。轻、中度放牧条件下，放牧对凋落物C/N比的影响与放牧对土壤C/N比的影响呈负相关，而在重度放牧条件下，两者呈正相关。而在轻、中度放牧条件下，放牧对根系C：P和土壤C：P的影响呈正相关，而在重度放牧条件下，二者呈负相关。重要的是，放牧显著降低了土壤N库10.0%，增加了土壤P库3.6%，说明放牧对草地N、P循环的影响机制不同。主要结论放牧强度通过影响植物养分利用效率和土壤物理化学过程来调节草地生态系统中C、N、P的生物地球化学循环。因此，将放牧强度纳入地球系统模型可能会改善对人类世气候-草原反馈的预测。
AimLivestock grazing can alter carbon (C), nitrogen (N) and phosphorus (P) cycles, thereby affecting the C : N : P stoichiometry in grasslands. In this study, we aimed to examine mechanisms underlying the impacts of grazing on grassland C : N : P stoichiometry, focusing on belowground processes and their linkages with aboveground vegetation properties.LocationGlobal.Time period1900–2018.Major taxa studiedGrassland ecosystems.MethodsWe conducted a meta‐analysis based on 129 published studies to synthesize the effects of grazing on the C : N : P stoichiometry of leaves, stems, litter, roots, microbial biomass, and soil in grassland ecosystems.ResultsGrazing significantly affected the C, N and P pools, and then the C : N : P stoichiometry in grassland ecosystems. Grazing effects on C : N : P stoichiometry varied strongly with grazing intensity. Specifically, heavy grazing decreased all C : N : P stoichiometry except litter N : P and root C : N ratios, while light and moderate grazing caused less negative or positive effects. Grazing effects on litter C : N ratio were negatively correlated with grazing effects on soil C : N ratios under light and moderate grazing, but this relationship was positive under heavy grazing. In contrast, grazing effects on root C : P and soil C : P were positively correlated under light and moderate grazing but negatively correlated under heavy grazing. Importantly, grazing significantly decreased the soil N pool by 10.0% but increased the soil P pool by 3.6%, indicating differential mechanisms for grazing impact on N and P cycles in grasslands.Main conclusionsOur results strongly suggest that grazing intensity regulates the biogeochemical cycles of C, N and P in grassland ecosystems by affecting plant nutrient use efficiency and soil physicochemical processes. Therefore, incorporating grazing intensity into Earth system models may improve predictions of climate–grassland feedbacks in the Anthropocene.