## 3 Results
### Impact of mTVWI on GPP  
The percentage change of GPP due to mTVWI is shown in Figure 4A-C. The largest decrease occurred in Mediterranean countries, whereas the smallest decrease occurred in Belarus and Norway for all considered years. Italy and Spain showed a GPP reduction ranging from 40 to 100%. Central Europe presented a GPP reduction ranging from 20 to 40% for all years except for 2007 and 2008, where the GPP reduction reached 80%. Northern and Northeastern Europe were characterized by a small GPP reduction (0-40%). Table 3 shows a plant species-based GPP reduction (%) for all years. Conifers showed a mean GPP reduction of nearly 50% ranging from 40% in _P. sylvestris_ to 80% in _P. halepensis, P. nigra_, and _P. pinaster_. The broad-leaf deciduous species showed an average GPP reduction close to 40%, with some species showing higher reductions (54%, _F. sylvalica_ and _Q. pubescens_) and other species with limited GPP reduction (20% _B. pubescens_, _B. pendula_, _P. tremula_). By contrast, _Q. ilex_ presented values of GPP reduction close to 70% for all considered years. Figures 5-9 show the average GPP reduction values over the time period 2000-2010 (standard deviations are shown in Figure S4). The largest decrease occurred in _F. sylvalica_, _P. halepensis, P. nigra, P. pinaster_, and _Q. ilex_, whereas the smallest decrease occurred in _B. pendula_ and _B. pubescens_.  
Figure 4: The percentage change of gross primary production (GPP) due to mTVWI, a proxy of soil water availability, over the time period 2000–2010.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**SPECICS**} & \multicolumn{1}{c}{**CFP Reduction (\%)**} & \multicolumn{1}{c}{**Figure 5: The mean species–specific GPP reduction (%) for _A. pseudoplatanus_, _A. glutinosa_, _B. pendula_, _B. pubescens_ over the time period 2000–2010.  
Figure 6: The mean species–specific GPP reduction (%) for C. _betulus_, _C. sativa_, _F. sylvariatica_, _F. excelsior_ over the time period 2000–2010.  
Figure 8: The mean species–specific GPP reduction (%) for _P. pinaster_, _P. sylvestris_, _P. tremula_, _Q. llex_ over the time period 2000–2010.  
Figure 7: The mean species–specific GPP reduction (%) for _L. decidua_, _P. abies_, _P. halepensis_, _P. nigra_ over the time period 2000–2010.  
In general, we found that broad-leaf evergreen (_Q.__ilex_) and confer species showed higher GPP reduction values than broad-leaf deciduous (Table 3), which was also confirmed by analysis of variance (ANOVA) and Tukey post hoc tests (Figure S5, Table S3). The anomalies analysis is shown in Figure 10. We found a species-specific pattern of GPP and mTVWI anomalies in the time period 2000-2010. In general, highly negative anomalies of mTVWI (a condition of severe aridity) often correspond to a reduction of GPP. Indeed, in 2008 a highly negative deviation from the grand mean corresponds to a GPP reduction in most of the considered species (e.g., _A.__pseudoplatanus_, _F.__sylvatica_, _P.__abies_, _L.__decidua_, _P.__tremula_). Taking into account the 2003 heat wave that affected much of Europe from June to September [69], we found a highly negative deviation from the grand mean of GPP not matching with high negative mTVWI anomalies.  
Figure 9: The mean species–specific GPP reduction (%) for _Q.__petraea_, _Q.__pubscens_, _Q.__robur_ over the time period 2000–2010.