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.

中文翻译：

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大规模遥感分析揭示草地活力与大气需水量的耦合日益增强

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。草原也容易受到干旱的影响，使其在气候变化下的未来活力变得不确定。然而，草原对干旱的反应尚不清楚，特别是对于异质的中欧草原。我们使用 Landsat/Sentinel-2 的新型遥感数据集与气候再分析数据相结合，量化草原对干旱的时空敏感性，从而填补了这一空白。具体来说，我们量化了 1985 年至 2021 年精细空间尺度和全国范围（德国）的年度草地活力。我们通过测试草地活力与常见干旱指数之间统计上稳健的联系来分析草地对干旱的敏感性。鉴于 12 种草原生境类型不同的生物和非生物特征，我们进一步探讨了干旱敏感性的时空变化。草地活力图显示，在过去的干旱期间，草地活力大幅下降。 2018-2019 年前所未有的干旱成为自 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相关（右2= .09–.22) 蒸气压不足最能解释活力。这表明，正如最近复合干旱和热浪事件中所观察到的那样，大气对水的高需求对中欧草原的活力产生了重大影响。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敏感性，这表明随着持续的气候变化，干旱对草原的影响变得更加严重。草原干旱敏感性的空间变异性与不同的生境类型有关，从干燥和中等生境到潮湿生境，敏感性下降。我们的研究提供了第一个大规模、长期和空间明确的证据，证明中欧草原的干旱敏感性不断增加。随着气候变化背景下复合干旱和热浪的加剧，未来像2018-2019年那样大规模的草地活力丧失的可能性将变得更大。