Investigating temporal variation in soil bacterial communities advances our fundamental understanding of the causal processes driving biological variation, and how the composition of these important ecosystem members may change into the future. Despite this, temporal variation in soil bacteria remains understudied, and the effects of spatial heterogeneity in bacterial communities on the detection of temporal changes is largely unknown. Using 16S rRNA gene amplicon sequencing, we evaluated temporal patterns in soil bacterial communities from indigenous forest and human-impacted sites sampled repeatedly over a 5-year period. Temporal variation appeared to be greater when fewer spatial samples per site were analysed, as well as in human-impacted compared to indigenous sites (P < 0.01 for both). The biggest portion of variation in bacterial community richness and composition was explained by soil physicochemical variables (13–24%) rather than spatial distance or sampling time (<1%). These results highlight the importance of adequate spatiotemporal replication when sampling soil communities for environmental monitoring, and the importance of conducting temporal research across a wide variety of land uses. This will ensure we have a true understanding of how bacterial communities change over space and time; the work presented here provides important considerations for how such research should be designed.

中文翻译：

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土壤细菌群落的时间变化可以与空间变化混淆。

调查土壤细菌群落的时间变化，使我们对驱动生物变化的因果过程以及这些重要的生态系统成员的组成如何在未来发生变化的方法有了基本的了解。尽管如此，土壤细菌的时间变化仍然未被充分研究，并且细菌群落中空间异质性对时间变化检测的影响在很大程度上是未知的。使用16S rRNA基因扩增子测序，我们评估了在5年期间重复采样的土著森林和人类影响站点的土壤细菌群落中的时间模式。当分析每个站点的空间样本较少时，以及在受人类影响的情况下，与本地站点相比，时间变化似乎更大（P两者均<0.01）。细菌群落丰富度和组成变化的最大部分是由土壤理化变量（13–24％）而不是空间距离或采样时间（<1％）解释的。这些结果突显了在对土壤群落进行采样以进行环境监测时，进行适当的时空复制的重要性，以及在多种土地用途上进行时间研究的重要性。这将确保我们对细菌群落如何随时间和空间变化有真正的了解。本文介绍的工作为如何设计此类研究提供了重要的考虑因素。