Dulwich College Beijing, Beijing, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
PeerJ. 2022 Feb 10;10:e12868. doi: 10.7717/peerj.12868. eCollection 2022.
Soil microbes are an essential component of terrestrial ecosystems and drive many biogeochemical processes throughout the soil profile. Prior field studies mainly focused on the vertical patterns of soil microbial communities, meaning their temporal dynamics have been largely neglected. In the present study, we investigated the vertical and temporal patterns of soil bacterial and archaeal communities in a wheat-soybean rotation agroecosystem at a depth of millions of sequences per sample. Our results revealed different vertical bacterial and archaeal richness patterns: bacterial richness was lowest in the deep soil layer and peaked in the surface or middle soil layer. In contrast, archaeal richness did not differ among soil layers. PERMANOVA analysis indicated that both bacterial and archaeal community compositions were significantly impacted by soil depth but unaffected by sampling time. Notably, the proportion of rare bacteria gradually decreased along with the soil profile. The rare bacterial community composition was the most important indicator for soil nutrient fertility index, as determined by random forest analysis. The soil prokaryotic co-occurrence networks of the surface and middle soil layers are more connected and harbored fewer negative links than that of the deep soil layer. Overall, our results highlighted soil depth as a more important determinant than temporal variation in shaping the soil prokaryotic community and interspecific interactions and revealed a potential role of rare taxa in soil biogeochemical function.
土壤微生物是陆地生态系统的重要组成部分，它们驱动着土壤剖面中许多生物地球化学过程。先前的野外研究主要集中在土壤微生物群落的垂直分布模式上，这意味着它们的时间动态在很大程度上被忽视了。在本研究中，我们在一个小麦-大豆轮作农业生态系统中，以每个样本数百万个序列的深度，调查了土壤细菌和古菌群落的垂直和时间分布模式。我们的结果揭示了不同的垂直细菌和古菌丰富度模式：细菌丰富度在深层土壤中最低，在表层或中层土壤中达到峰值。相比之下，古菌丰富度在不同土层之间没有差异。PERMANOVA 分析表明，细菌和古菌群落组成都受到土壤深度的显著影响，但不受采样时间的影响。值得注意的是，稀有细菌的比例随着土壤剖面的加深而逐渐减少。稀有细菌群落组成是随机森林分析确定的土壤养分肥力指数的最重要指标。表层和中层土壤的土壤原核共生网络比深层土壤更具连接性，且负面连接较少。总体而言，我们的结果强调了土壤深度是塑造土壤原核生物群落和种间相互作用的更重要决定因素，揭示了稀有类群在土壤生物地球化学功能中的潜在作用。
