Data for: Positive legacies of severe droughts in the Inner Mongolia grassland

Global change-induced extreme droughts are increasing in grasslands worldwide, and drought legacies may greatly affect the responses of grassland ecosystems to these changes. However, it remains poorly understood whether and how severe droughts have a positive legacy effect on grassland productivity. By combining a 4-year precipitation manipulation experiment with a 40-year observational study in a semiarid grassland, we showed that extreme droughts could create strong positive legacies on community productivity, and that such legacies could last for multiple years. The mechanism behind this was the coupled effect of the drought-induced increase in annuals and the favorable precipitation pattern that facilitated the flourishing of annuals in subsequent years. This study provides experimental and observational evidence for novel positive drought legacies and reveals their underlying mechanisms. Our findings suggest that positive drought legacies should be incorporated into Earth system models to better predict the impact of extreme droughts on grassland ecosystems.

全球变化驱动的极端干旱事件在全球草原生态系统中愈发频发，而干旱遗留效应可能会极大影响草原生态系统对这类变化的响应。然而，目前仍不清楚极端干旱是否会对草原生产力产生积极遗留效应，以及其具体作用机制。本研究通过对半干旱草原开展为期4年的降水控制实验与40年的长期定位观测相结合的研究方案，证实极端干旱可对群落生产力产生显著的积极遗留效应，且该效应可延续多年。其背后的作用机制为：干旱诱导一年生植物种群扩张，加之后续年份有利的降水格局进一步促进了一年生植物的繁盛，二者共同产生耦合效应。本研究为新型干旱积极遗留效应提供了实验与观测证据，并揭示了其内在作用机制。本研究结果表明，应将干旱积极遗留效应纳入地球系统模式（Earth system models），以更精准地预测极端干旱对草原生态系统的影响。