Background and aims

The increasing occurrence of extreme drought events under climate change alters the composition and functioning of plant communities worldwide. Drought-induced changes in plant-soil feedback (PSF), reciprocal effects on fitness between plants and their associated soil microbial communities, are one mechanism through which these changes in vegetation occur, but they remain difficult to predict. Because of their direct link to rhizosphere microbial communities, we expect root traits to predict drought-induced PSF shifts.

Methods

In the conditioning phase of a greenhouse experiment, we subjected 12 common grassland species to drought. In the feedback phase, all species were grown under ambient conditions with their own microbial inoculum. Their growth was compared to growth in sterile soil to assess total PSF or soil inoculated with microbes from three other species to assess specific PSF. We used root traits to predict PSF under drought and ambient conditions.

Results

Drought altered the magnitude and direction of PSF in a quarter of the species, which was consistent between total and specific PSF. Total PSF was best predicted by the first axis of the root trait space (high specific root length to high root diameter and root nitrogen content) and was not responsive to drought. Specific PSF was weakly predicted by root traits and changed in response to drought.

Conclusion

Our results show that drought can modify the feedbacks between plants and their microbial communities with implications for vegetation dynamics. Root traits have limited capacity to predict these shifts, but can predict PSF of the total microbial community independent of drought.

中文翻译：

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植物-土壤对干旱的反馈反应是物种特异性的，仅通过根系性状进行勉强预测

 背景和目标

气候变化下极端干旱事件的发生率不断增加，改变了全球植物群落的组成和功能。干旱引起的植物-土壤反馈 （PSF） 变化，即植物与其相关土壤微生物群落之间对适应性的相互影响，是植被发生这些变化的一种机制，但它们仍然难以预测。由于它们与根际微生物群落直接相关，我们预计根性状可以预测干旱引起的 PSF 变化。

 方法

在温室实验的调节阶段，我们对 12 种常见的草原物种进行了干旱。在反馈阶段，所有物种都在环境条件下使用自己的微生物接种物生长。将它们的生长与无菌土壤中的生长进行比较，以评估总 PSF 或接种其他三个物种的微生物的土壤以评估特定的 PSF。我们使用根性状来预测干旱和环境条件下的 PSF。

 结果

干旱改变了四分之一物种 PSF 的大小和方向，这在总 PSF 和特定 PSF 之间是一致的。总 PSF 最好地通过根性状空间的第一轴（高比根长到高根直径和根氮含量）预测，并且对干旱没有反应。根系性状对特异性 PSF 的预测较弱，并随着干旱而变化。

 结论

我们的结果表明，干旱可以改变植物与其微生物群落之间的反馈，从而影响植被动态。根性状预测这些变化的能力有限，但可以独立于干旱预测总微生物群落的 PSF。