草原为社会提供重要的生态系统服务,包括生物多样性,水安全,侵蚀控制,和饲料生产。草原也很容易受到干旱的影响,在不确定的气候变化下赋予他们未来的活力。然而,草原对干旱的反应还不清楚,特别是对于异质的中欧草原。我们在这里通过使用Landsat/Sentinel-2的新型遥感数据集与气候重新分析数据配对,量化草地对干旱的时空敏感性来填补这一空白。具体来说,我们量化了1985年至2021年在精细空间尺度和国家范围(德国)的年度草地活力。我们通过测试草地生命力与常见干旱指数之间的统计上牢固的联系,分析了草地对干旱的敏感性。鉴于12种草地生境类型的生物和非生物特征不同,我们还探索了干旱敏感性的时空变化。草原活力图显示了过去干旱期间草原活力的大规模减少。2018-2019年前所未有的干旱是自20世纪80年代中期以来最大的多年活力下降。草原活力始终与干旱(R2=.09-.22)相结合,蒸气压力不足解释了活力。这表明高大气需水量,正如在最近的干旱和热浪事件中观察到的那样,对中欧的草原活力有重大影响。我们发现,随着时间的推移,干旱敏感性显着增加,在大气需水量极高的时期检测到最高的敏感性,这表明,随着气候变化的持续,干旱对草原的影响变得越来越严重。草地干旱敏感性的空间变异性与不同的生境类型有关,从干燥和中等到潮湿栖息地的敏感性下降。我们的研究提供了第一个大规模的,长期的,以及中欧草原干旱敏感性增加的空间明确证据。随着气候变化下的复合干旱和热浪上升,大规模的草原生命力丧失,如2018-2019年,未来将变得更有可能。
Grasslands provide important ecosystem services to society, including biodiversity, water security, erosion control, and forage production. Grasslands are also vulnerable to droughts, rendering their future vitality under climate change uncertain. Yet, the grassland response to drought is not well understood, especially for heterogeneous Central European grasslands. We here fill this gap by quantifying the spatiotemporal sensitivity of grasslands to drought using a novel remote sensing dataset from
Landsat/Sentinel-2 paired with climate re-analysis data. Specifically, we quantified annual grassland vitality at fine spatial scale and national extent (Germany) from 1985 to 2021. We analyzed grassland sensitivity to drought by testing for statistically robust links between grassland vitality and common drought indices. We furthermore explored the spatiotemporal variability of drought sensitivity for 12 grassland habitat types given their different biotic and abiotic features. Grassland vitality maps revealed a large-scale reduction of grassland vitality during past droughts. The unprecedented drought of 2018-2019 stood out as the largest multi-year vitality decline since the mid-1980s. Grassland vitality was consistently coupled to drought (R2 = .09-.22) with Vapor Pressure Deficit explaining vitality best. This suggests that high atmospheric water demand, as observed during recent compounding drought and heatwave events, has major impacts on grassland vitality in Central Europe. We found a significant increase in drought sensitivity over time with highest sensitivities detected in periods of extremely high atmospheric water demand, suggesting that drought impacts on grasslands are becoming more severe with ongoing climate change. The spatial variability of grassland drought sensitivity was linked to different habitat types, with declining sensitivity from dry and mesic to wet habitats. Our study provides the first large-scale, long-term, and spatially explicit evidence of increasing drought sensitivities of Central European grasslands. With rising compound droughts and heatwaves under climate change, large-scale grassland vitality loss, as in 2018-2019, will thus become more likely in the future.