CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
Mol Ecol. 2021 Feb;30(4):1072-1085. doi: 10.1111/mec.15777. Epub 2020 Dec 26.
Although many studies have investigated the spatial scaling of microbial communities living in surface soils, very little is known about the patterns within deeper strata, nor is the mechanism behind them. Here, we systematically assessed spatial scaling of prokaryotic biodiversity within three different strata (Upper: 0-20 cm, Middle: 20-40 cm, and Substratum: 40-100 cm) in a typical grassland by examining both distance-decay (DDRs) and species-area relationships (SARs), taxonomically and phylogenetically, as well as community assembly processes. Each layer exhibited significant biogeographic patterns in both DDR and SAR (p < .05), with taxonomic turnover rates higher than phylogenetic ones. Specifically, the spatial turnover rates, β and z values, respectively, ranged from 0.016 ± 0.005 to 0.023 ± 0.005 and 0.065 ± 0.002 to 0.077 ± 0.004 across soil strata, and both increased with depth. Moreover, the prokaryotic community in grassland soils assembled mainly according to deterministic rather than stochastic mechanisms. By using normalized stochasticity ratio (NST) based on null model, the relative importance of deterministic ratios increased from 48.0 to 63.3% from Upper to Substratum, meanwhile a phylogenetic based method revealed average βNTI also increased with depth, from -5.29 to 19.5. Using variation partitioning and distance approaches, both geographic distance and soil properties were found to strongly affect biodiversity structure, the proportions increasing with depth, but spatial distance was always the main underlying factor. These indicated increasingly deterministic proportions in accelerating turnover rates for spatial assembly of prokaryotic biodiversity. Our study provided new insights on biogeography in different strata, revealing importance of assembly patterns and mechanisms of prokaryote communities in below-surface soils.
尽管许多研究已经调查了生活在表层土壤中的微生物群落的空间尺度,但对于更深层次的地层中的模式知之甚少,也不知道其背后的机制。在这里,我们通过检查距离衰减(DDR)和物种-面积关系(SAR),从分类和系统发育以及群落组装过程的角度,系统地评估了典型草原中三个不同地层(上层:0-20cm、中层:20-40cm 和底层:40-100cm)中原核生物多样性的空间尺度。每个层在 DDR 和 SAR 中都表现出显著的生物地理模式(p<0.05),分类周转率高于系统发育周转率。具体而言,空间周转率β和 z 值分别在 0.016±0.005 至 0.023±0.005 和 0.065±0.002 至 0.077±0.004 之间变化,且随深度增加而增加。此外,草原土壤中原核生物群落主要根据确定性而不是随机机制组装。通过使用基于 null 模型的归一化随机比(NST),确定性比的相对重要性从上层到底层从 48.0%增加到 63.3%,同时基于系统发育的方法表明平均βNTI 也随深度增加而增加,从-5.29 增加到 19.5。通过变异划分和距离方法,地理距离和土壤特性都被发现强烈影响生物多样性结构,比例随深度增加,但空间距离始终是主要的潜在因素。这表明,在加速原核生物生物多样性的空间组装中,确定性比例不断增加。我们的研究为不同地层的生物地理学提供了新的见解,揭示了组装模式和机制在地下土壤中原核生物群落中的重要性。