Ongoing climate change, as well as long-term overgrazing, is threatening biodiversity and ecosystem functioning in grasslands worldwide. Climate change and grazing could directly alter ecosystem functioning and stability, or indirectly by changing species diversity, composition and plant functional traits. By synthesizing results from publications of the most recent 30-years, we found that effects of climate change and grazing on biodiversity and ecosystem functioning varied from positive to negative, depending on different scenarios. Generally, aboveground net primary production (ANPP), belowground net primary production (BNPP), and species richness showed strong negative responses to 4°C warming, 50% precipitation decrease, and high grazing intensity. Responses of ANPP, BNPP and species richness to precipitation increase were mostly positive, whereas their responses to 2°C warming and low-to-moderate grazing intensity varied from positive to negative. Negative effects of 2°C warming on ANPP were substantially greater in grasslands that had been grazed than those that had not been grazed, and larger in arid and semi-arid grasslands than those in sub-humid and humid grasslands. Under 50% precipitation increase, ANPP responses were larger in grazed than ungrazed grasslands, and bigger in arid and semi-arid than sub-humid and humid grasslands. High levels of grazing intensity had greater effects on productivity and species richness than did warming and precipitation decrease. Currently, although there are increasing number of experiments which have included both climate change and grazing factors, more studies are needed to test the joint effects of climate change (e.g. warming, changes in precipitation patterns) and grazing (grazing intensity and livestock type) on biodiversity and multiple ecosystem functions. Multi-factor experiments would provide a more comprehensive understanding for sustainable grassland management in future.

持续的气候变化以及长期的过度放牧，正威胁着世界范围内草原的生物多样性和生态系统的功能。气候变化和放牧可直接改变生态系统的功能和稳定性，或通过改变物种多样性，组成和植物功能性状间接改变。通过综合最近30年的出版物的结果，我们发现气候变化和放牧对生物多样性和生态系统功能的影响从积极到消极，取决于不同的情况。通常，地上净初级生产力（ANPP），地上净初级生产力（BNPP）和物种丰富度对4°C变暖，降水减少50％和高放牧强度表现出强烈的负响应。ANPP，BNPP和物种丰富度对降水增加的响应大部分为正，而它们对2°C变暖和中低度放牧强度的响应从正到负变化。放牧的草原上2​​°C变暖对ANPP的负面影响要比未放牧的草原大得多，在干旱和半干旱的草原上要比在半湿润和湿润的草原上大。在降水增加50％以下的情况下，放牧的草地的ANPP响应要大于未耕种的草地，而干旱和半干旱的草地的ANPP响应要比半湿润和湿润的草地更大。高放牧强度比变暖和降水减少对生产力和物种丰富度的影响更大。目前，尽管越来越多的实验同时包括气候变化和放牧因素，但仍需要进行更多研究以测试气候变化的共同影响（例如变暖，生物多样性和多种生态系统功能的放牧方式的变化）和放牧（放牧强度和牲畜类型）。多因素实验将为将来的可持续草地管理提供更全面的理解。