Data from: Microbial richness and composition independently drive soil multifunctionality

Soil microbes provide multiple ecosystem functions such as nutrient cycling, decomposition and climate regulation. However, we lack a quantitative understanding of the relative importance of microbial richness and composition in controlling multifunctionality. This knowledge gap limits our capacity to understand the influence of biotic attributes in the provision of services and functions on which humans depend.
We used two independent approaches (i.e. experimental and observational), and applied statistical modeling to identify the role and relative importance of bacterial richness and composition in driving multifunctionality (here defined as seven measures of respiration and enzyme activities). In the observational study we measured soil microbial communities and functions in both tree- and bare soil-dominated microsites at 22 locations across a 1200 km transect in southeastern Australia. In the experimental study we used soils from two of those locations and developed gradients of bacterial diversity and composition through inoculation of sterilized soils.
Microbial richness and the relative abundance of γ-Proteobacteria, Actinobacteria and Bacteroidetes were positively related to multifunctionality in both the observational and experimental approaches; however, only Bacteroidetes was consistently selected as a key predictor of multifunctionality across all experimental approaches and statistical models used here. Moreover, our results, from two different approaches, provide evidence that microbial richness and composition are both important, yet independent, drivers of multiple ecosystem functions.
Overall, our findings advance our understanding of the mechanisms underpinning relationships between microbial diversity and ecosystem functionality in terrestrial ecosystems, and further suggest that information on microbial richness and composition needs to be considered when formulating sustainable management and conservation policies, and when predicting the effects of global change on ecosystem functions.

土壤微生物可介导养分循环、有机质分解与气候调节等多项生态系统功能。然而，当前学界对微生物丰富度与群落组成在调控生态系统多功能性（multifunctionality）中的相对重要性尚缺乏定量认知，这一认知缺口限制了我们理解生物属性对人类赖以生存的生态服务与功能的影响能力。
本研究采用实验与观测两种独立研究方法，并结合统计建模，以明确细菌丰富度与群落组成在驱动生态系统多功能性（此处定义为7项呼吸作用与酶活性指标）中的作用及相对重要性。在观测研究中，我们于澳大利亚东南部一条1200公里的样带上的22个采样点，分别测定了树木主导与裸土主导微生境中的土壤微生物群落与生态功能。在控制实验中，我们选取上述两个采样点的土壤，通过向灭菌土壤中接种不同菌群，构建了细菌多样性与群落组成梯度。
在观测与实验两种研究范式中，微生物丰富度以及γ-变形菌门（γ-Proteobacteria）、放线菌门（Actinobacteria）与拟杆菌门（Bacteroidetes）的相对丰度均与生态系统多功能性呈正相关；但在本研究使用的所有实验方法与统计模型中，仅拟杆菌门（Bacteroidetes）始终被筛选为生态系统多功能性的关键预测因子。此外，基于两种不同研究方法得到的结果证实，微生物丰富度与群落组成均为驱动多项生态系统功能的重要且独立的影响因子。
总体而言，本研究结果深化了我们对陆地生态系统中微生物多样性与生态系统功能间关联机制的理解，同时提示在制定可持续管理与保护政策，以及预测全球变化对生态系统功能的影响时，需纳入微生物丰富度与群落组成相关信息。