Data from: Effects of between-site variation in soil microbial communities and plant-soil feedbacks on the productivity and composition of plant communities

A critical challenge in the science and practice of restoration ecology is to understand the drivers of variation in restoration outcomes. Soil microbial communities may have a role in explaining this variation due to both site-to-site variation in the composition of soil microbial communities and due to variation that can arise due to plant-soil feedbacks. We tested the relative importance of between-site variation in soil microbial community composition and plant-soil feedbacks in shaping plant community composition and ecosystem function.

We used a standard two-phase plant-soil feedback design. Soil inoculum was collected from four tallgrass prairie sites. Then, soils were conditioned separately with nine plant species, and conditioned soils were used to inoculate prairie community mesocosms. In a separate experiment using soil from an additional site we tested conditioned soil samples for the abundance of arbuscular mycorrhizal fungi (AMF) and rhizobia.

Site of soil origin and plant-soil feedbacks both had effects on the composition and productivity of our plant communities, and the magnitudes of these effects were similar. We also found changes in the abundance of AMF and rhizobia due to plant-soil feedbacks and that AMF abundance were associated with differences in plant community composition.

These results indicate that the composition of soil communities due to site-to-site variation and plant-soil feedbacks are both important determinants of plant community composition and productivity. Our results also suggest that AMF and rhizobia are key microbial functional groups underlying plant-soil feedback effects.

Synthesis and applications. Site-to-site variation in soil communities can explain some variation in restoration of plant communities. Since plant-soil feedback effects of restored plant species do not overcome this variation, knowledge of soil microbial communities present at a site prior to initiation of restoration efforts may improve predictability of restoration outcomes, and reintroduction of some components of the soil community may be necessary to achieve restoration goals. Additionally, by understanding variation due to plant-soil feedbacks, restoration practitioners can choose plant species for reintroduction that will create favourable soil conditions, including promoting microbial mutualists. Plant-soil feedbacks should also make it possible to increase heterogeneity in soil microbial communities, leading to increases in beta diversity in plant communities.

恢复生态学（restoration ecology）的科学研究与实践面临的一项核心挑战，是阐明恢复结局差异的驱动因素。由于土壤微生物群落（soil microbial communities）组成存在位点间差异，且植物-土壤反馈（plant-soil feedbacks）可产生额外变异，土壤微生物群落或许能解释这类恢复结局的差异。本研究针对土壤微生物群落组成的位点间差异与植物-土壤反馈在塑造植物群落组成及生态系统功能中的相对重要性开展了验证。

我们采用了标准的两阶段植物-土壤反馈实验设计。土壤接种物采自4个高草草原（tallgrass prairie）样地。随后，我们分别用9种植物对土壤进行驯化，再将驯化后的土壤用于接种草原群落中型生态系统（mesocosm）。在另一项使用额外样地土壤的实验中，我们检测了驯化土壤样品中丛枝菌根真菌（arbuscular mycorrhizal fungi）与根瘤菌（rhizobia）的丰度。

土壤来源样地与植物-土壤反馈均对植物群落的组成与生产力产生了影响，且二者的效应强度相近。我们还发现，植物-土壤反馈会改变丛枝菌根真菌与根瘤菌的丰度，且丛枝菌根真菌丰度与植物群落组成的差异存在显著关联。

上述结果表明，由位点间差异形成的土壤群落组成，以及植物-土壤反馈，均是决定植物群落组成与生产力的关键因素。本研究结果还提示，丛枝菌根真菌与根瘤菌是介导植物-土壤反馈效应的核心微生物功能群。

综合与应用。土壤群落的位点间差异可解释植物群落恢复过程中的部分变异。由于恢复植物物种的植物-土壤反馈效应无法抵消这类差异，在启动恢复工作前，了解样地中原有的土壤微生物群落组成，或可提升恢复结局的可预测性；而为达成恢复目标，或许还需要重新引入部分土壤群落组分。此外，通过解析植物-土壤反馈带来的变异，恢复生态学从业者可选择适宜的重新引入植物物种，以构建有利的土壤环境，包括促进微生物共生体的生长。植物-土壤反馈还可提升土壤微生物群落的异质性，进而推动植物群落的β多样性（beta diversity）提升。