Aims

Drought events can alter the composition of plant and soil communities, and are becoming increasingly common and severe due to climate change. However, how droughts affect plant-soil feedbacks is still poorly understood. Plants accumulate species-specific rhizosphere communities, and droughts may have varying impacts across plant species and soil biota. We therefore tested the hypothesis that drought alters plant-soil feedbacks differently among closely related plant species that differ in their preferences for soil moisture.

Methods

In a two-phase greenhouse experiment, we first conditioned grassland soil with seven Geranium species and, as controls, we conditioned soil with a grass species or left soil unplanted. In the second phase, we grew the Geranium species in conspecific, grass-conditioned and unplanted soil, maintained soil moisture at 5 %, 10 % or 20 % (w/w), and determined biomass responses after 35 days.

Results

Independent of conditioning, plants showed a weaker performance with decreasing soil moisture. Under the driest conditions, soil conditioning by conspecifics most negatively affected relative root weight in comparison to plants growing in unplanted control soil, while the effects of conspecific conditioning on relative root weights were species-specific when compared to plants grown in grass-conditioned control soil.

Conclusions

We conclude that decreased soil moisture modified plant-soil feedback effects on biomass allocation, and that these modifications acted in species-specific ways. However, drought effects on plant-soil feedbacks were subtle, and did not affect overall plant performance. Therefore, plant-soil feedback effects on plant performance during a drought event may be limited in comparison with the direct effects of drought.

中文翻译：

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干旱改变植物-土壤反馈对生物量分配的影响，但对植物性能没有影响

目的

干旱事件可以改变植物和土壤群落的组成，并且由于气候变化而变得越来越普遍和严重。但是，干旱对植物土壤反馈的影响仍然知之甚少。植物积累了特定物种的根际群落，干旱可能对植物物种和土壤生物区系产生不同的影响。因此，我们检验了以下假设：干旱在密切相关的植物物种对土壤水分的偏好不同的情况下，改变植物-土壤反馈的方式也不同。

方法

在一个两阶段的温室实验中，我们首先用7种天竺葵对土壤进行调理，并作为对照，对一种草种或未种植的土壤进行了调理。在第二阶段中，我们将天竺葵种种种植在特定的，经过草皮处理且未种植的土壤中，将土壤湿度保持在5％，10％或20％（w / w），并在35天后确定生物量响应。

结果

与调节无关，植物显示出随着土壤湿度降低而变弱的性能。在最干旱的条件下，与未种植的对照土壤中生长的植物相比，通过种特异性进行的土壤条件对相对根重的负面影响最大，而与在草条件的对照土壤中生长的植物相比，同种条件对相对根重的影响具有物种特异性。 。

结论

我们得出结论，减少土壤水分会改变植物-土壤对生物量分配的反馈影响，并且这些改变以物种特定的方式起作用。然而，干旱对植物-土壤反馈的影响是微妙的，并且不影响植物的整体性能。因此，与干旱的直接影响相比，干旱事件期间植物-土壤反馈对植物性能的影响可能受到限制。