干旱和热浪是全球温带半干旱草地植被生产力丧失的主要极端气候,挑战这些地区的生态系统生产力稳定性。先前的研究表明,全球草地生产力对干旱的抵抗力显着下降,但是我们仍然缺乏对确定草地对干旱和热浪的时空变化的机制的系统理解。在这项研究中,我们专注于中国的温带半干旱草原(TSGC),以评估草地生产力对不同极端气候的抵抗力的时空变化:复合干热事件,个别干旱事件,以及2000-2019年期间发生的个别热浪事件。基于可解释的机器学习模型,我们探索了对干旱和热浪相互作用的抗性,并确定了决定抗性时空变化的主要因素。结果表明,锡林郭勒草原和毛乌素沙地的草地对极端气候的抵抗力下降,在2000-2019年期间,Otindag沙漠没有显着增加。人类活动和CO2浓度的增加导致毛乌素沙地的抗性下降,VPD的增加和植被损失事件时间的转移导致锡林郭勒草原的抗性下降,而极端气候的减弱,特别是干旱持续时间的缩短,增加Otindag沙漠的抵抗力。年平均温度主导了不同草地之间阻力的空间差异。当干旱和热浪同时发生时,与单个干旱和热浪事件相比,对抗性有加性效应,对复合干热事件的抗性较低。我们的分析为了解极端气候对中国温带半干旱草原的影响提供了至关重要的见解。
Drought and
heatwave are the primary climate extremes for vegetation productivity loss in the global temperate semi-arid grassland, challenging the ecosystem productivity stability in these areas. Previous studies have indicated a significant decline in the resistance of global grassland productivity to drought, but we still lack a systematic understanding of the mechanisms determining the spatiotemporal variations in grassland resistance to drought and
heatwave. In this study, we focused on temperate semi-arid grasslands of China (TSGC) to assess the spatiotemporal variations of grassland productivity resistance to different climate extremes: compound dry-hot events, individual drought events, and individual heatwave events that occurred during 2000-2019. Based on the explainable machine learning model, we explored the resistance to the interaction of drought and
heatwave and identify the dominant factors determining the spatiotemporal variations in resistance. The results revealed that grassland resistance to climate extremes had decreased in Xilingol Grassland and Mu Us Sandy Land, and had a not significant increase in Otindag Desert during 2000-2019. Human activities and the increase in CO2 concentration causes a decline in resistance in Mu Us Sandy Land, and the increase of VPD and shift of vegetation loss event timing caused a decline in resistance in Xilingol Grassland, while the weakening of climate extremes, especially the shortening of drought duration, increase the resistance in Otindag Desert. Mean annual temperature dominates the spatial differences in resistance among different grasslands. When drought and
heatwave occur simultaneously, there is an additive effect on resistance and causes lower resistance to compound dry-hot events compared to individual drought and
heatwave events. Our analysis provides crucial insights into understanding the impact of climate extremes on the temperate semi-arid grasslands of China.