Data from: Complementarity and selection effects in early and mid-successional plant communities are differentially affected by plant-soil feedback

1. Many studies that provided evidence for a positive relationship between
plant diversity and productivity have proposed that this effect may be
explained by complementarity among species in resources utilization, or
selection of particularly productive species in high-diversity plant
communities. Recent studies have related the higher productivity in
diverse plant communities to suppression of pathogenic soil biota. If soil
biota plays a role in diversity–productivity relationships, the question
remains about how they may influence complementarity and selection
effects. 2. Here we examine how complementarity and selection effects may
depend on soil biota using a plant–soil feedback approach. We used
monocultures and mixtures of early successional plant species, which are
known to have mostly negative plant–soil feedback effects, and
mid-successional plant species, which generally have neutral plant–soil
feedback. 3. We found that plant–soil feedback effects differed between
monocultures and mixed plant communities, as well as between early and
mid-successional plants. This resulted in a significant interaction effect
between diversity and successional stage. In monocultures, plant–soil
feedback tended to be negative for early and positive for mid-successional
plant species. Interestingly, the community feedback responses of the
mixed communities were opposite, being positive for early and negative for
mid-successional community. 4. Plant–soil feedback differentially affected
complementarity and selection effects of early and mid-successional plant
communities: it enhanced complementarity effects of early and decreased
selection effects of mid-successional species. 5. Synthesis. Soil biota
that drive plant–soil feedback effects can influence the
diversity–productivity relationship not only through decreased biomass
production in monocultures compared to mixtures, but also through
influencing complementarity and selection effects among species in mixed
plant communities. Our results reveal that biodiversity–productivity
relationships depend on plant–soil feedback interactions, which depend on
the successional position of the plant. We propose that including
successional position and trait-based analyses of plant–soil feedback in
diversity-functioning studies will enhance understanding consequences of
biodiversity loss for productivity and other ecosystem processes.

1. 已有多项研究证实植物多样性（plant diversity）与生产力（productivity）之间存在正相关关联，并提出该效应可通过两种机制解释：一是物种间资源利用的生态位互补效应（complementarity effect），二是高多样性植物群落中高生产力物种的选择效应（selection effect）。近期研究则将多样植物群落的更高生产力归因于病原性土壤生物群（pathogenic soil biota）的抑制作用。若土壤生物群在多样性-生产力关系中发挥调控作用，那么关于它们如何影响互补效应与选择效应的问题仍有待解答。
2. 本研究借助植物-土壤反馈（plant–soil feedback, PSF）方法，探究互补效应与选择效应如何受土壤生物群的调控。我们选取了两类植物类群：已知大多表现为负向植物-土壤反馈效应的早期演替植物物种，以及通常呈现中性植物-土壤反馈效应的中期演替植物物种，并分别设置单作群落（monocultures）与混植群落（mixtures）处理组。
3. 研究结果显示，植物-土壤反馈效应在单作与混植群落间存在显著差异，同时在早期与中期演替植物类群间亦有所不同，由此形成了多样性与演替阶段间的显著交互效应。在单作群落中，早期演替植物的植物-土壤反馈效应多为负值，而中期演替植物则多为正值。值得注意的是，混植群落的群落水平反馈响应恰好相反：早期演替混植群落的反馈效应为正值，中期演替混植群落则为负值。
4. 植物-土壤反馈对早期与中期演替植物群落的互补效应与选择效应存在差异化调控：它增强了早期演替群落的互补效应，却削弱了中期演替物种的选择效应。
5. 综合分析：驱动植物-土壤反馈效应的土壤生物群，可通过两种途径影响多样性-生产力关系：一是相较于混植群落，单作群落的生物量生产受到抑制；二是调控混植群落内物种间的互补效应与选择效应。本研究结果表明，生物多样性-生产力关系依赖于植物-土壤反馈交互作用，而该交互作用又取决于植物的演替地位。我们建议，在多样性-生态系统功能研究中纳入植物演替地位与基于功能性状的植物-土壤反馈分析，将有助于深化对生物多样性丧失对生产力及其他生态系统过程影响的认知。