Effects of grazing on soil nitrogen spatial heterogeneity depend on herbivore assemblage and pre-grazing plant diversity
Effects of grazing on soil nitrogen spatial heterogeneity depend on herbivore assemblage and pre-grazing plant diversity
复制标题
放牧对土壤氮空间异质性的影响取决于草食动物组合和放牧前植物多样性
DOI：
10.1111/1365-2664.12537
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发表时间：
2016
影响因子：
5.7
通讯作者：
Lin Haijiao
中科院分区：
文献类型：
--
作者：
Liu Chen;Song Xuxin;Wang Ling;Wang Deli;Zhou Xiaomei;Liu Jun;Zhao Xuan;Li Jing;Lin Haijiao
限制土壤资源的空间异质性是决定生态系统过程和功能的重要因素。大型草食动物对土壤氮素的变化和空间分布格局具有重要影响。然而，目前尚不清楚大型草食动物如何影响土壤空间异质性，以及这种影响是否依赖于植物群落多样性。和牛羊混合放牧]在欧亚大陆东部草原上，放牧前植物多样性高和低的草地土壤氮的空间异质性。我们发现，草食动物放牧产生并维持了空间异质性，土壤养分的模式，取决于草食动物组合和放牧前植物多样性的水平。放牧增加了羊草草原草甸土壤速效N的空间异质性，这种空间异质性与放牧前植物多样性无关。然而，SG和MG的效应强烈依赖于草地植物多样性，在高多样性草地中增加了土壤速效N的空间异质性，而在低多样性草地中则没有。我们得出的结论是，在羊草占主导地位的欧亚大陆东部草原，养牛可以被认为是一个最佳的放牧管理协议，以改善土壤空间异质性，因为放牧（CG）持续增加土壤的空间异质性，在低和高植物多样性的背景下。然而，土壤空间异质性可以改善任何草食动物放牧制度[CG和/或绵羊放牧（SG）]时，保持高植物多样性。这些发现凸显了保护植物多样性对维持草原结构和生态系统功能的重要性。在植物多样性较高的草地系统中，草食动物放牧和植物多样性共同改善土壤空间异质性，从而反馈维持较高的植物多样性。因此，在放牧草地系统中，高植物多样性可以产生一个正反馈的食草动物-植物-土壤相互作用回路。我们的研究结果表明，草食动物组合在维持低多样性和高多样性草地系统的空间异质性的重要性。
The spatial heterogeneity of limiting soil resources is an essential factor determining ecosystem processes and function. It has been reported that large herbivores can strongly impact the variation and spatial distribution pattern of soil nitrogen (N). However, it remains unclear how large herbivores affect soil spatial heterogeneity and whether this influence is dependent on plant community diversity.Here we examined effects of different herbivore assemblages [no grazing; cattle grazing (CG); sheep grazing (SG); and mixed grazing (MG) of cattle and sheep] on soil N spatial heterogeneity in grasslands with high and low pre‐grazing plant diversity in an eastern Eurasian steppe.We found that herbivore grazing generated and maintained spatial patterns of soil nutrients, depending on herbivore assemblage and the level of pre‐grazing plant diversity. CG increased the spatial heterogeneity of soil available N inLeymus chinensis‐dominated steppe meadows, which were independent of pre‐grazing plant diversity. However, the effects of SG and MG strongly depended on grassland plant diversity, with an increased spatial heterogeneity of soil available N in the high‐diversity grassland, but not in the low‐diversity grassland.Synthesis and applications. We concluded that in aL. chinensis‐dominated eastern Eurasian steppe, cattle ranching could be considered as an optimal grazing management protocol to improve soil spatial heterogeneity because cattle grazing (CG) consistently increased soil spatial heterogeneity in the context of both low and high plant diversity. Nevertheless, soil spatial heterogeneity could be improved by any herbivore grazing regime [CG and/or sheep grazing (SG)] when high plant diversity is maintained. These findings highlight the importance of conserving plant diversity to maintain grassland structure and ecosystem function. In grassland systems with high plant diversity, herbivore grazing and plant diversity would jointly improve soil spatial heterogeneity, thus feeding back to maintain higher plant diversity. Therefore, high plant diversity could generate a positive feedback loop of herbivore–plant–soil interactions in grazed grassland systems. Our findings indicate the importance of herbivore assemblages in maintaining spatial heterogeneity in low‐ and high‐diversity grassland systems.