## 3 Results
### Water Budgets of Historical Time Series  
When comparing the period 1961-1990 with 1991-2019, the temperature increased by \(\sim\)1 \({}^{\circ}\)C from 8.0 \(\pm\) 0.2 \({}^{\circ}\)C to 9.0 \(\pm\) 0.2 \({}^{\circ}\)C (Table 2, Table S2). This increase was constant over all sites (Figure 3). Within the whole time period 1961-2019, a linear trend was significant (Figure 3, Table S3). With 9.5 \(\pm\) 0.3 \({}^{\circ}\)C, the current decade is 0.6 \({}^{\circ}\)C warmer compared to the preceding decade. \begin{table}
\begin{tabular}{l l l l l l l l l l} \hline \hline
**RCP** & **Model** & **T’C1** & **P [mm]** & **PET [mm]** & **CWB [mm]** & **ET [mm]** & **Tr [mm]** & **S [mm]** & **SW200 [mm]** & **TI [d]** \\ \hline hist & 1961–1990 & 8.0 \(\pm\) 0.1\({}^{\ast}\) & 584 \(\pm\) 16\({}^{\ast}\) & 513 \(\pm\) 6\({}^{\ast}\) & 71 \(\pm\) 20\({}^{\ast}\) & 454 \(\pm\) 2\({}^{\ast}\) & 274 \(\pm\) 4\({}^{\ast}\) & 117 \(\pm\) 9\({}^{\ast}\) & 155 \(\pm\) 2\({}^{\ast}\) & 42 \(\pm\) 4\({}^{\ast}\)\({}^{\ast}\)\({}^{\ast}\)\({}^{\ast}\) \\ hist & 1991–2019 & 9.0 \(\pm\) 0.1\({}^{\ast}\) & 609 \(\pm\) 18\({}^{\ast}\) & 548 \(\pm\) 7\({}^{\ast}\) & 61 \(\pm\) 22\({}^{\ast}\) & 480 \(\pm\) 9\({}^{\ast}\) & 296 \(\pm\) 6\({}^{\ast}\) & 116 \(\pm\) 8\({}^{\ast}\) & 154 \(\pm\) 2\({}^{\ast}\) & 49 \(\pm\) 5\({}^{\ast}\)\({}^{\ast}\) \\
2.6 & ECE/RCA4 & 9.7 \(\pm\) 0.1\({}^{\ast}\) & 629 \(\pm\) 17\({}^{\ast}\) & 642 \(\pm\) 10\({}^{\ast}\) & \(-\)13 \(\pm\) 24\({}^{\ast}\) & 472 \(\pm\) 8\({}^{\ast}\) & 286 \(\pm\) 4\({}^{\ast}\) & 143 \(\pm\) 8\({}^{\ast}\) & 162 \(\pm\) 3\({}^{\ast}\) & 34 \(\pm\) 2\({}^{\ast}\)\({}^{\ast}\)\({}^{\ast}\) \\
2.6 & MPI/Remo & 9.6 \(\pm\) 0.1\({}^{\ast}\) & 638 \(\pm\) 17\({}^{\ast}\) & 643 \(\pm\) 8\({}^{\ast}\) & \(-\)5 \(\pm\) 23\({}^{\ast}\) & 457 \(\pm\) 5\({}^{\ast}\) & 275 \(\pm\) 3\({}^{\ast}\) & 180 \(\pm\) 11\({}^{\ast}\) & 169 \(\pm\) 3\({}^{\ast}\) & 29 \(\pm\) 4\({}^{\ast}\)With 584 \(\pm\) 16 mm to 609 \(\pm\) 18 mm, precipitation did not increase significantly (Table 2). The decade 2001-2010 had the highest precipitation values with 644 \(\pm\) 33 mm on average. Precipitation in the current decade is 592 \(\pm\) 38 mm lower. In none of the sites, a significant linear trend was evident (Figure 3). The temperature increase was accompanied by a significant increase of PET from 513 \(\pm\) 6 mm to 548 \(\pm\) 7 mm on average between both time periods. The increase was significant on all sites. CWB did not change significantly. Actual evaporation increased significantly from 454 \(\pm\) 7 mm in 1961-1990 to 480 \(\pm\) 9 mm in 1991-2019. Moreover, transpiration increased from 274 \(\pm\) 4 mm to 296 \(\pm\) 6 mm. A linear trend was significant for transpiration and actual evapotranspiration within the whole period 1961-2019 (Figure 3). Seepage and soil water storage down to 2 m (SW200) remained unchanged between both periods. The number of dry days per year (TI) did not increase significantly between the periods 1961-1990 and 1991-2019 with 42 \(\pm\) 4 days to 49 \(\pm\) 5 days (Table 2), but a linear trend was significant over the whole period (Figure 3, Table S3). The change between both periods was significant on the beech site 1302, where it increased from 40 \(\pm\) 4 days to 52 \(\pm\) 5 days. The current decade exhibited, with 56 \(\pm\) 11 days on average, the highest number of dry days. Our results demonstrate that 2018 was the driest year on average within the historical time period 1961-2019. This is shown by precipitation with 404 \(\pm\) 15 mm, climatic water balance with \(-\)259 \(\pm\) 30 mm, transpiration with 237 \(\pm\) 12 mm, and 124 \(\pm\) 7 dry days (Figure 3). Soil water content is in 2018 with 139 \(\pm\) 20 mm not as extreme as the other indicators, and with 177 \(\pm\) 19 mm, seepage is even higher than the average (Table 2), but in 2019 seepage is, with 74 \(\pm\) 12 mm, distinctly lower and soil water content keeps, with 137 \(\pm\) 19 mm, the same level compared to 2018.