Wildfire activity and the hydrological cycle are strongly interlinked. While it is well known that wildfire occurrence and intensity are controlled by water availability, less is known about the effects of wildfire on plant and soil water cycling, especially at large scales. Here we investigate this by analysing fire impacts on the coupling between plant and soil water content, at the global scale, using remote sensing of soil moisture, vegetation water content and burned area. We find a strong effect of fire on plant–soil water relations, accelerating soil moisture loss by 17% and leading to faster gains in vegetation water content by 62%, both of which are positively related to fire severity and largest in forests. This effect is spatially extensive, with accelerated soil moisture loss found in 67%, and increased vegetation water content gain found in 67% of all analysed burned areas. After fire, plants also tended to have less control on their water content (that is, were more anisohydric). In summary, fire changes ecosystem functioning by increasing ecosystem water losses and shifting the relationship between soil and vegetation water budgets. With climate change, wildfire is likely to play an increasingly important role in ecosystem water cycling and subsequent ecosystem recovery.

野火活动和水文循环密切相关。虽然众所周知，野火的发生和强度受水的可用性控制，但对野火对植物和土壤水分循环的影响知之甚少，尤其是在大规模的情况下。在这里，我们通过使用土壤湿度、植被含水量和燃烧面积的遥感，在全球范围内分析火灾对植物和土壤含水量之间耦合的影响来研究这一点。我们发现火灾对植物-土壤水分关系有很强的影响，土壤水分流失加速了 17%，导致植被含水量更快增加 62%，这两者都与火灾的严重程度呈正相关，在森林中最大。这种影响在空间上是广泛的，在所有分析的燃烧区域中，67% 的土壤水分流失加速，植被含水量增加。火灾后，植物对其含水量的控制也往往较少（即，更不合时宜）。总之，火灾通过增加生态系统水分流失和改变土壤和植被水收支之间的关系来改变生态系统的功能。随着气候变化，野火可能在生态系统水循环和随后的生态系统恢复中发挥越来越重要的作用。