The succession of arbuscular mycorrhizal fungi (AMF) communities during ecosystem development has received widespread attention, but the ecological mechanism that drives the succession of AMF communities during the restoration process in alpine meadow ecosystems remains unclear. Here, we treated ‘Black Beach’ (severely degraded alpine meadow) as the baseline for restoration (0 year), and selected the revegetated grassland of Elymus nutans with different planting times (3, 7, 10, and 14 years) to analyze the species composition of the AMF community in mixed roots (at the whole-plant-community scale) and in E. nutans roots (at the single-plant-species scale). A total of 46 AMF phylotypes (mixed roots: 44; E. nutans roots: 46) were identified in both root systems, predominantly belonging to Glomeraceae. AMF species richness showed a single-peak curve change across the restoration time and reached its peak at 3 years in both root systems. In mixed roots, the soil available nitrogen not only directly changed the AMF species composition but also indirectly changed the AMF species composition through plant richness. In the E. nutans roots, only the soil available nitrogen drove changes in AMF species composition through changes in plant richness. Our results indicate that E. nutans, a key species in the restoration process of revegetated grassland, can enhance its regulation to assemble the AMF community through soil available nitrogen at the two research scales, suggesting that the scientific management of soil nitrogen availability during restoration succession could strengthen the mutual symbiosis of ‘plant-AMF,’ thereby retarding the occurrence of secondary degradation of revegetated grassland.

中文翻译：

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Elymus nutans对青藏高原植被恢复演替中土壤速效氮促进丛枝菌根真菌群落组合的影响

丛枝菌根真菌（AMF）群落在生态系统发育过程中的演替受到广泛关注，但高寒草甸生态系统恢复过程中驱动AMF群落演替的生态机制尚不清楚。在这里，我们以“黑滩”（严重退化的高寒草甸）作为恢复基线（0年），并选择不同种植时间（3、7、10和14年）的Elymus nutans重新植被草地来分析混合根（全植物群落规模）和E. nutans根（单植物物种规模）中 AMF 群落的物种组成。共有 46 个 AMF 系统型（混合根：44；E. nutans根：46）在两个根系中都被鉴定出来，主要属于肾小球科。AMF 物种丰富度在恢复时间内呈现出单峰曲线变化，并在两个根系中均在 3 年时达到峰值。在混合根中，土壤有效氮不仅直接改变了AMF物种组成，而且通过植物丰富度间接改变了AMF物种组成。在E. nutans根中，只有土壤有效氮通过植物丰富度的变化来驱动 AMF 物种组成的变化。我们的结果表明E. nutans, 是植被恢复过程中的关键物种, 可以在两个研究尺度上通过土壤有效氮加强其调控以聚集 AMF 群落, 表明恢复演替过程中土壤氮有效性的科学管理可以加强 ' 的相互共生。植物-AMF，从而延缓了植被草地二次退化的发生。