Fig. 4. Species-specific response of tree water deficit (TWD) ratio to vapour pressure deficit (VPD) and relative extractable water (REW) in the hydrometeorological space for most abundant and economically valuable tree species in Europe.

a–d, Linear-mixed effect model output of the ratio of the daily minimum TWD during the 2018 heatwave compared to the 95^th percentile of the control period (TWD_2018:control), while VPD₂₀₁₈ and REW₂₀₁₈ refer to the absolute values during 2018 heatwave. All trees of Fagus sylvatica, Quercus spp. (Q. robur/petraea), Picea abies and Pinus sylvestris within the database are considered. From the hydrometeorological space range of the entire database (indicated in grey), models have been adjusted for the common climatic range of the selected species only (indicated with dotted lines; see Supplementary Fig. 4 for the climate range of each species). e Bars indicate the percentage of the hydrometeorological space covering different ranges of min. TWD_2018:control values (see legend).