Data from: Impacts of grazing by different large herbivores in grassland depend on plant species diversity

1. It is well documented that large herbivores have pronounced effects on
plant communities in grassland ecosystems, and the extent and course of
their effects can largely depend on both plant and herbivore
characteristics. Previous studies highlighted the importance of plant
productivity in predicting the impact of herbivores on grasslands. Yet,
there has been little consideration of how different herbivores affect
plant communities that, in turn, differ in plant diversity. 2. In a 2-year
grazing experiment, we tested the effects of large herbivores (cattle or
sheep, or both together) on plant communities under high and low plant
diversity levels in eastern Eurasian steppe. 3. We found that, for high
plant diversity grassland, mixed grazing by cattle and sheep significantly
increases plant diversity, but we found no effect of grazing by cattle or
sheep alone. Grazing by cattle or sheep alone or mixed grazing by cattle
and sheep did not significantly affect plant biomass in the high diversity
grassland. However, for low plant diversity grassland, grazing by cattle
alone and mixed grazing by cattle and sheep significantly increased plant
diversity, but significantly decreased plant biomass. There was no
significant impact on both plant diversity and biomass from sheep grazing.
4. Synthesis and applications. We conclude that the effects of grazing in
grassland strongly depend on herbivore assemblages and pre-grazing plant
diversity. Herbivore grazing might contribute more to the maintenance of
grassland structure and ecosystem functioning under high plant diversity
compared with low plant diversity. Furthermore, our data suggest that
multiple-species mixed grazing regimes in grassland systems with high
plant diversity could represent the optimal protocol for grazing
management. This study emphasizes the importance of maintaining both plant
and herbivore diversity to optimize ecosystem functioning.

1. 已有充分文献表明，大型草食动物对草原生态系统中的植物群落具有显著影响，其影响的程度与过程在很大程度上取决于植物和草食动物双方的特征。以往研究强调了植物生产力在预测草食动物对草原影响方面的重要性。然而，关于不同草食动物如何影响本身植物多样性存在差异的植物群落，相关研究却鲜有涉及。
2. 在一项为期两年的放牧实验中，我们在欧亚大陆东部草原的高、低植物多样性水平下，测试了大型草食动物（牛、羊或两者混养）对植物群落的影响。
3. 结果发现，在高植物多样性草原中，牛和羊混养的放牧方式显著提高了植物多样性，但单独放牧牛或羊则无此效应；无论是单独放牧牛、羊还是两者混养，均未对高多样性草原的植物生物量产生显著影响。然而，在低植物多样性草原中，单独放牧牛和两者混养均显著提高了植物多样性，但显著降低了植物生物量；单独放牧羊则对植物多样性和生物量均无显著影响。
4. 综合与应用。我们得出结论：草原放牧效应强烈依赖于草食动物组合及放牧前的植物多样性水平。相较于低植物多样性的草原，草食动物放牧可能更有助于维持高植物多样性草原的结构与生态系统功能。此外，我们的数据表明，在高植物多样性的草原系统中，多物种混养模式或许是最优的放牧管理方案。本研究强调了维持植物和草食动物多样性对优化生态系统功能的重要性。