Understanding the processes that underpin the community assembly of bacteria is a key challenge in microbial ecology. We studied soil bacterial communities across a large-scale successional gradient of managed and abandoned grasslands paired with mature forest sites to disentangle drivers of community turnover and assembly. Diversity partitioning and phylogenetic null-modelling showed that bacterial communities in grasslands remain compositionally stable following abandonment and secondary succession but they differ markedly from fully afforested sites. Zeta diversity analyses revealed the persistence of core microbial taxa that both reflected and differed from whole-scale community turnover patterns. Differences in soil pH and C:N were the main drivers of community turnover between paired grassland and forest sites and the variability of pH within successional stages was a key factor related to the relative dominance of deterministic assembly processes. Our results indicate that grassland microbiomes could be compositionally resilient to abandonment and secondary succession and that the major changes in microbial communities between grasslands and forests occur fairly late in the succession when trees have established as the dominant vegetation. We also show that core taxa may show contrasting responses to management and abandonment in grasslands.

中文翻译：

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核心类群支撑次生演替过程中土壤微生物群落的更替

了解细菌群落组装的过程是微生物生态学的一个关键挑战。我们研究了管理和废弃草地与成熟森林地点的大规模演替梯度中的土壤细菌群落，以理清群落更替和聚集的驱动因素。多样性划分和系统发育零模型表明，草原中的细菌群落在废弃和次生演替后仍保持组成稳定，但与完全绿化的地区明显不同。Zeta 多样性分析揭示了核心微生物类群的持久性，它既反映又不同于整个群落的周转模式。土壤 pH 值和 C:N 的差异是配对草地和森林之间群落更替的主要驱动因素，演替阶段 pH 值的变化是与确定性组装过程的相对优势相关的关键因素。我们的研究结果表明，草原微生物群落在组成上可能对废弃和次生演替具有抵抗力，并且草原和森林之间微生物群落的主要变化发生在演替的相当后期，此时树木已成为主要植被。我们还表明，核心类群可能对草原的管理和废弃表现出截然不同的反应。