In summer 2018, Europe experienced a record drought, but it remains unknown how the drought affected ecosystem carbon dynamics. Using observations from 34 eddy covariance sites in different biomes across Europe, we studied the sensitivity of gross primary productivity (GPP) to environmental drivers during the summer drought of 2018 versus the reference summer of 2016. We found a greater drought-induced decline of summer GPP in grasslands (−38%) than in forests (−10%), which coincided with reduced evapotranspiration and soil water content (SWC). As compared to the ‘normal year’ of 2016, GPP in different ecosystems exhibited more negative sensitivity to summer air temperature (Ta) but stronger positive sensitivity to SWC during summer drought in 2018, that is, a stronger reduction of GPP with soil moisture deficit. We found larger negative effects of Ta and vapour pressure deficit (VPD) but a lower positive effect of photosynthetic photon flux density on GPP in 2018 compared to 2016, which contributed to reduced summer GPP in 2018. Our results demonstrate that high temperature-induced increases in VPD and decreases in SWC aggravated drought impacts on GPP.

This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

2018 年夏季，欧洲经历了创纪录的干旱，但干旱如何影响生态系统碳动态仍然未知。使用来自欧洲不同生物群落的 34 个涡流协方差点的观察结果，我们研究了 2018 年夏季干旱与 2016 年参考夏季期间总初级生产力 (GPP) 对环境驱动因素的敏感性。我们发现干旱引起的夏季下降幅度更大草原 (-38%) 的 GPP 高于森林 (-10%)，这与蒸发蒸腾和土壤含水量 (SWC) 的减少相吻合。与 2016 年“正常年”相比，2018 年夏季干旱期间不同生态系统的 GPP 对夏季气温 (Ta) 表现出更多的负敏感性，但对 SWC 的正敏感性更强，即随着土壤水分亏缺 GPP 的下降幅度更大.

本文是主题问题“2018 年欧洲严重干旱和热浪的影响：从场地到大陆尺度”的一部分。