Data from: Phylogenetic relatedness, phenotypic similarity, and plant-soil feedbacks

1.Plant-soil feedbacks contribute to species invasions, the maintenance of biodiversity, and climate change impacts on terrestrial ecosystems. Despite their far-reaching importance, we lack a general understanding of the ecological and evolutionary determinants of plant-soil feedbacks.

2.We conducted a large-scale plant-soil feedback experiment using 49 co-occurring plant species from southern Ontario, Canada, representing a wide phylogenetic range. We tested whether effects of soil conditioning varies among these species, and whether different focal species respond similarly to the same soil conditioning. Next, we asked whether plant traits and soil feedbacks depend upon phylogenetic similarity, and which plant traits affect plant-soil feedbacks between pairs of plant species. Finally we used our experimental results to test whether soil feedbacks affect co-occurrence of species in the field.

3.We found evidence of both strong positive and negative soil feedbacks between pairs of plant species. Our soil conditioning treatment explained nearly 20% of the variation in focal species performance.

4.Phylogenetic relatedness and phenotypic similarity between plant species were unrelated to the strength of their soil feedback. However, numerous plant traits of the conditioning species influenced the strength of soil feedbacks on focal species, including specific leaf area and total aboveground productivity. Trait differences between species were also predictive of plant-soil feedbacks, though for some pairs of species, increased trait differences were associated with positive plant-soil feedbacks and for others trait differences were associated with negative plant-soil feedbacks.

5.Plant species co-occurrence in the field was related to their experimentally determined soil feedbacks but only for particular plant species.

6.Synthesis. Our results illustrate how evolutionary history and phenotypic variation shape plant-soil feedbacks and highlight the need for trait-based studies. Due to the unique evolutionary history of individual traits and the variability in their importance across all possible interacting species, we show that indices of overall phenotypic and phylogenetic relatedness are poor predictors of plant-soil feedbacks at large phylogenetic scales. We conclude that a detailed trait-based approach can be used to predict plant-soil feedbacks, and laboratory measures of soil feedbacks can explain patterns of co-occurrence in nature.

1. 植物-土壤反馈（plant-soil feedbacks）参与调控物种入侵、生物多样性维持以及气候变化对陆地生态系统的影响。尽管其影响范围极为广泛，但目前学界尚未形成对植物-土壤反馈的生态与进化决定因子的普适性认知。
2. 本研究针对加拿大安大略省南部的49种同域共存植物物种开展了大规模植物-土壤反馈实验，这些物种涵盖了广泛的系统发育（phylogenetic）谱系。我们首先检验了不同物种间土壤预培养效应的差异，以及不同目标物种对同一土壤预培养处理的响应是否一致；其次探究了植物功能性状与植物-土壤反馈是否依赖于系统发育相似性，以及哪些植物功能性状会影响物种对之间的植物-土壤反馈强度；最后利用实验结果验证了土壤反馈是否会影响野外自然群落中物种的共存格局。
3. 本研究观测到物种对之间同时存在显著正向与负向的植物-土壤反馈；土壤预培养处理可解释近20%的目标物种生长表现的变异。
4. 植物物种间的系统发育亲缘关系与表型相似性，均与其植物-土壤反馈强度无显著关联。然而，土壤预培养物种的诸多功能性状会显著影响其对目标物种的土壤反馈强度，其中包括比叶面积（specific leaf area）与地上总生产力。物种间的性状差异同样可以预测植物-土壤反馈强度：部分物种对的性状差异增大与正向植物-土壤反馈相关，而另一部分物种对的性状差异增大则与负向植物-土壤反馈相关。
5. 野外自然群落中的植物物种共存格局，仅在部分植物类群中与其实验测定的植物-土壤反馈强度相关。
6. 【研究总结】本研究阐明了进化历史与表型变异如何塑造植物-土壤反馈，并凸显了开展基于功能性状研究的必要性。由于单个功能性状具有独特的进化历史，且其在不同互作物种组合中的重要性存在差异，我们的研究表明，在大尺度系统发育范围内，整体表型与系统发育亲缘关系指数无法有效预测植物-土壤反馈强度。本研究最终得出结论：精细化的基于功能性状的研究方法可用于预测植物-土壤反馈，而实验室测定的土壤反馈结果能够解释自然群落中的物种共存格局。