1. The spatial heterogeneity of soil limiting resources is one of the most important factors maintaining biodiversity and ecosystem functions. There is a general concern that herbivore grazing plays a central role in modifying soil resources heterogeneity. However, most studies have examined how large herbivores as a group affect soil heterogeneity. There is limited knowledge about how assemblages of different herbivore species may influence soil heterogeneity, and whether the herbivore assemblage effects might vary with grassland types.
2. Here we conducted a 4‐year grazing experiment to examine the effects of different herbivore assemblages (no grazing; cattle grazing; sheep grazing; and mixed grazing of cattle and sheep) on the spatial heterogeneity of soil N availability across three types of grasslands (meadow steppe, typical steppe and desert steppe) in eastern Eurasian steppe.
3. The results showed that all the herbivore grazing increased the heterogeneity of soil N availability in the three grasslands with different precipitation (only cattle grazing and mixed grazing of cattle and sheep in meadow steppe did not reach a statistically significant level). The consistently increased heterogeneity of soil N availability was primarily due to the effect of animal excreta addition, which weakened in drier grasslands, likely because of the slower excreta decomposition. Moreover, sheep excreta contributed more to soil N heterogeneity than that of other herbivore assemblages, and the effect was statistically significant in meadow steppe and typical steppe with relative high precipitation.
4. Synthesis and applications. Our study indicates that sheep could have larger potential to maintain and enhance grassland heterogeneity than cattle especially in grassland ecosystems with high precipitation. We therefore suggest that managing above‐ground herbivore species is important for conserving and promoting grassland soil heterogeneity, and that the management should also take into account local environmental conditions such as precipitation.

中文翻译：

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草食动物组合对东部欧亚草原土壤氮空间异质性的影响

1. 土壤限制资源的空间异质性是维持生物多样性和生态系统功能的最重要因素之一。人们普遍担心食草动物放牧在改变土壤资源异质性方面起着核心作用。但是，大多数研究都检查了大型草食动物作为一个整体如何影响土壤异质性。关于不同草食动物物种的组合如何影响土壤异质性以及草食动物组合效应是否会随草地类型的变化而知之甚少。
2. 在这里，我们进行了为期4年的放牧实验，以研究不同草食动物组合（不放牧；牛放牧；绵羊放牧；以及牛羊混合放牧）对三种草地（草地）上土壤氮素有效性空间异质性的影响草原，典型的草原和沙漠草原）。
3. 结果表明，所有食草动物放牧增加了三个降水量不同的草原土壤氮素有效性的异质性（仅草原草地的牛放牧和牛羊混合放牧没有达到统计学上的显着水平）。土壤氮素有效性的异质性持续增加主要是由于动物排泄物添加的影响，在较干旱的草原上动物排泄物的添加减弱了，这可能是由于排泄物分解较慢所致。此外，绵羊排泄物对土壤氮异质性的贡献比其他草食动物组合更大，在草甸草原和典型的相对高降水量的草原上，这种作用具有统计学意义。
4. 综合与应用。我们的研究表明，与牛相比，绵羊在保持和增强草原异质性方面具有更大的潜力，特别是在高降水量的草原生态系统中。因此，我们建议管理地上食草动物物种对于保护和促进草原土壤异质性很重要，并且该管理还应考虑当地的环境条件，例如降水。