State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing, 210008, China.
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
Microbiome. 2018 Feb 5;6(1):27. doi: 10.1186/s40168-018-0409-4.
The relative importance of stochasticity versus determinism in soil bacterial communities is unclear, as are the possible influences that alter the balance between these. Here, we investigated the influence of spatial scale on the relative role of stochasticity and determinism in agricultural monocultures consisting only of wheat, thereby minimizing the influence of differences in plant species cover and in cultivation/disturbance regime, extending across a wide range of soils and climates of the North China Plain (NCP). We sampled 243 sites across 1092 km and sequenced the 16S rRNA bacterial gene using MiSeq. We hypothesized that determinism would play a relatively stronger role at the broadest scales, due to the strong influence of climate and soil differences in selecting many distinct OTUs of bacteria adapted to the different environments. In order to test the more general applicability of the hypothesis, we also compared with a natural ecosystem on the Tibetan Plateau.
Our results revealed that the relative importance of stochasticity vs. determinism did vary with spatial scale, in the direction predicted. On the North China Plain, stochasticity played a dominant role from 150 to 900 km (separation between pairs of sites) and determinism dominated at more than 900 km (broad scale). On the Tibetan Plateau, determinism played a dominant role from 130 to 1200 km and stochasticity dominated at less than 130 km. Among the identifiable deterministic factors, soil pH showed the strongest influence on soil bacterial community structure and diversity across the North China Plain. Together, 23.9% of variation in soil microbial community composition could be explained, with environmental factors accounting for 19.7% and spatial parameters 4.1%.
Our findings revealed that (1) stochastic processes are relatively more important on the North China Plain, while deterministic processes are more important on the Tibetan Plateau; (2) soil pH was the major factor in shaping soil bacterial community structure of the North China Plain; and (3) most variation in soil microbial community composition could not be explained with existing environmental and spatial factors. Further studies are needed to dissect the influence of stochastic factors (e.g., mutations or extinctions) on soil microbial community distribution, which might make it easier to predictably manipulate the microbial community to produce better yield and soil sustainability outcomes.
在土壤细菌群落中，随机性与决定性的相对重要性尚不清楚，可能会改变这种平衡的影响因素也不清楚。在这里，我们研究了空间尺度对农业单一种植（仅包括小麦）中随机性和决定性相对作用的影响，从而最大程度地减少了植物物种覆盖和种植/干扰制度差异的影响，研究范围涵盖了中国北方平原（NCP）的广泛土壤和气候。我们在 1092 公里的范围内采样了 243 个地点，并使用 MiSeq 对 16S rRNA 细菌基因进行了测序。我们假设，由于气候和土壤差异强烈影响了对不同环境有适应性的许多不同细菌 OTUs 的选择，因此在最广泛的尺度上，决定性将发挥相对更强的作用。为了检验该假设的更普遍适用性，我们还与青藏高原上的自然生态系统进行了比较。
我们的研究结果表明，随机性与决定性的相对重要性确实随空间尺度而变化，符合我们的预测。在中国北方平原，随机性在 150 到 900 公里（站点对之间的距离）之间起主导作用，而在 900 公里以上（大尺度）则由决定性起主导作用。在青藏高原上，决定性在 130 到 1200 公里之间起主导作用，而在 130 公里以下则由随机性起主导作用。在可识别的决定性因素中，土壤 pH 对中国北方平原土壤细菌群落结构和多样性的影响最大。共有 23.9%的土壤微生物群落组成变化可以用环境因素解释，其中环境因素占 19.7%，空间参数占 4.1%。
我们的研究结果表明，（1）随机过程在中国北方平原更为重要，而定性过程在青藏高原更为重要；（2）土壤 pH 是塑造中国北方平原土壤细菌群落结构的主要因素；（3）土壤微生物群落组成的大部分变化无法用现有环境和空间因素来解释。需要进一步研究来剖析随机因素（例如突变或灭绝）对土壤微生物群落分布的影响，这可能会使人们更容易预测性地操纵微生物群落，从而产生更好的产量和土壤可持续性结果。
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