Past research on plant-soil feedbacks (PSF), largely undertaken in highly controlled greenhouse conditions, has established that plant species differentially alter abiotic and biotic soil conditions that in turn affect growth of other conspecific and heterospecific individuals in that soil. Yet, whether feedbacks under controlled greenhouse conditions reflect feedbacks in natural environments where plants are exposed to a range of abiotic and biotic pressures is still unresolved. To address how environmental context affects PSF, we conducted a meta-analysis of previously published studies that examined plant growth responses to multiple forms of competition, stress, and disturbance across various PSF methodology. We asked the following questions: (1) Can competition, stress, and disturbance alter the direction and/or strength of PSF? (2) Do particular types of competition, stress, or disturbance affect the direction and/or strength of PSF more than others? and (3) Do methods of conducting PSF research (i.e., greenhouse vs. field experiments and whether the source of soil inoculum conditioning is from the field vs. greenhouse) affect plant growth responses to PSF or competition, stress, and disturbance, or their interactions? We discovered four patterns that may be predictive of what future PSF studies conducted under more realistic conditions might reveal. First, relatively little is known about how PSF responds to environmental stress and disturbance compared to plant-plant competition. Second, specific types of competition enhanced negative effects of soil microbes on plant growth, and specific environmental stressors enhanced positive effects of soil microbes on plant growth. Third, whether PSF experiments are conducted in the field or greenhouse can change plant growth responses. And, fourth, how the soil conditioning phase is conducted can change plant growth responses. With more detail than previously shown, these results confirm that environmental context writ large can change plant growth responses in PSF experiments. These data should aid theory and predictions for conservation and restoration applications by showing the relative importance of competition, stress, and disturbance in PSF studies over time. Lastly, these data demonstrate how variation in experimental methods can alter interpretation and conclusions of PSF studies.

中文翻译：

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预测田间植物-土壤反馈：元分析揭示竞争和环境压力对 PSF 的影响有差异

过去对植物-土壤反馈 (PSF) 的研究主要是在高度受控的温室条件下进行的，已经确定植物物种会不同地改变非生物和生物土壤条件，进而影响该土壤中其他同种和异种个体的生长。然而，受控温室条件下的反馈是否反映了植物暴露于一系列非生物和生物压力的自然环境中的反馈仍然没有解决。为了解决环境背景如何影响 PSF，我们对先前发表的研究进行了荟萃分析，这些研究检查了植物生长对各种 PSF 方法中多种形式的竞争、压力和干扰的反应。我们问了以下问题：（1）竞争、压力、和干扰改变 PSF 的方向和/或强度？(2) 特定类型的竞争、压力或干扰对 PSF 的方向和/或强度的影响是否大于其他类型？(3) 进行 PSF 研究的方法（即温室与田间试验以及土壤接种调节源是否来自田间与温室）是否会影响植物对 PSF 或竞争、压力和干扰的生长反应，或它们的互动？我们发现了四种模式，可以预测未来在更现实条件下进行的 PSF 研究可能会揭示什么。首先，与植物-植物竞争相比，关于 PSF 如何应对环境压力和干扰的知识相对较少。其次，特定类型的竞争增强了土壤微生物对植物生长的负面影响，和特定的环境压力因素增强了土壤微生物对植物生长的积极影响。第三，无论是在田间还是温室中进行 PSF 实验都会改变植物的生长反应。第四，如何进行土壤调理阶段可以改变植物的生长反应。这些结果比之前显示的更详细，证实了环境背景可以改变 PSF 实验中的植物生长反应。这些数据应该通过显示 PSF 研究中竞争、压力和干扰随时间推移的相对重要性来帮助保护和恢复应用的理论和预测。最后，这些数据证明了实验方法的变化如何改变 PSF 研究的解释和结论。无论是在田间还是在温室中进行 PSF 实验都可以改变植物的生长反应。第四，如何进行土壤调理阶段可以改变植物的生长反应。这些结果比之前显示的更详细，证实了环境背景可以改变 PSF 实验中的植物生长反应。这些数据应该通过显示 PSF 研究中竞争、压力和干扰随时间推移的相对重要性来帮助保护和恢复应用的理论和预测。最后，这些数据证明了实验方法的变化如何改变 PSF 研究的解释和结论。无论是在田间还是在温室中进行 PSF 实验都可以改变植物的生长反应。第四，如何进行土壤调理阶段可以改变植物的生长反应。这些结果比之前显示的更详细，证实了环境背景可以改变 PSF 实验中的植物生长反应。这些数据应该通过显示 PSF 研究中竞争、压力和干扰随时间推移的相对重要性来帮助保护和恢复应用的理论和预测。最后，这些数据证明了实验方法的变化如何改变 PSF 研究的解释和结论。这些结果比之前显示的更详细，证实了环境背景可以改变 PSF 实验中的植物生长反应。这些数据应该通过显示 PSF 研究中竞争、压力和干扰随时间推移的相对重要性来帮助保护和恢复应用的理论和预测。最后，这些数据证明了实验方法的变化如何改变 PSF 研究的解释和结论。这些结果比之前显示的更详细，证实了环境背景可以改变 PSF 实验中的植物生长反应。这些数据应该通过显示 PSF 研究中竞争、压力和干扰随时间推移的相对重要性来帮助保护和恢复应用的理论和预测。最后，这些数据证明了实验方法的变化如何改变 PSF 研究的解释和结论。