Theory predicts that stable species coexistence will occur when population growth rates of competitively dominant species are suppressed when at high conspecific density. Although there is now compelling evidence that plant communities exhibit negative density dependence, the relative importance of the underlying processes leading to these patterns is rarely tested. We coupled reciprocal greenhouse and field experiments with community dynamics modeling to untangle the relative importance of soil biota from competition as stabilizing forces to coexistence. We found that (1) plant-soil biotic interactions compared to competitive interactions were stronger stabilizing forces, (2) only the strength of plant-soil biotic interactions was dependent on plant evolutionary history, and (3) the variation in the strength of plant-soil biotic interactions was correlated with relative abundance patterns in an opposite way than was the variation in the strength of competitive interactions. Collectively, our results demonstrate the fundamental role soil biota have in maintaining plant community diversity.

中文翻译：

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土壤生物群增加了竞争植物物种共存的可能性

理论预测，当在高同种密度下竞争优势物种的种群增长率受到抑制时，将出现稳定的物种共存。尽管现在有令人信服的证据表明植物群落表现出负密度依赖性，但很少测试导致这些模式的潜在过程的相对重要性。我们将互惠温室和田间试验与群落动力学模型相结合，以解开土壤生物群的相对重要性，从竞争作为稳定力量到共存。我们发现（1）与竞争性相互作用相比，植物-土壤生物相互作用具有更强的稳定力，（2）只有植物-土壤生物相互作用的强度取决于植物进化史，(3) 植物-土壤生物相互作用强度的变化与相对丰度模式的相关性与竞争相互作用强度的变化相反。总的来说，我们的结果证明了土壤生物群在维持植物群落多样性方面的基本作用。