## 3 Results
### Spatial Pattern and Interannual Dynamics of GPP across Europe from 2001 to 2016
#### 3.1.2 Proportional Increase in GPP and LAI with Rapid Forest Growth across Europe  
Spatially, the interannual GPP trends (ranging between \(-\)40 and 40 g C m\({}^{-2}\) yr\({}^{-2}\)) showed widespread (71.6% of the vegetated area) increases in most of Europe (Figure 2a), among which 13.3% and 2.0% of European vegetated land exhibited significant increasing and decreasing GPP trends (\(p\) < 0.05), respectively (Figure 2c). The GPP of southern, central, and north-eastern Europe showed a significant increasing trend, while the vegetation productivity of a few countries (e.g., France, Ukraine, and Russia in south-eastern Europe) showed a negative trend. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multirow{2}{*}{**All**} & \multicolumn{3}{c}{**Land Use and Land Cover**} & \multicolumn{3}{c}{**Climate Change**} & \multicolumn{3}{c}{**CO\({}_{2}\)**} & \multirow{2}{*}{ \begin{tabular}{c} **Photosynthesis** \\ **Capacity (PC)** \\ \end{tabular}  } \\  & & & **Change (LULCC)** & & & & & & & & \\ \hline Scenario & All & LULCC1 & LULCC2 & LULCC3 & CLM1 & CLM2 & CLM3 & CLM4 & CO\({}_{2}\) & PC1 \\  & All & All – S1 & All – S2 & All – S3 & All – S4 & All – S5 & All – S6 & All – S7 & All – S8 & All – S9 \\ Simulation & All & S1 & S2 & S3 & S4 & S5 & S6 & S7 & S8 & S9 \\ LULC & \(\triangle\) & \(\blacktriangle\) & \(\blacktriangle\) & \(\blacktriangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ LAI & \(\triangle\) & \(\blacktriangle\) & \(\triangle\) & \(\blacktriangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ DSR & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\blacktriangle\) & \(\blacktriangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ TEMP & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\blacktriangle\) & \(\blacktriangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ VPD & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ CO\({}_{2}\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) & \(\triangle\) \\ V\({}_{\text{cmax}}\) & \(\triangle\) &Here, we used LAI to quantify greening. The spatial distribution of the GPP trend correlated well with the vegetation greening trends (Figure 2b). The spatial signature of the LAI trend suggested widespread (73.2% of the vegetated area) greening phenomena across Europe (Figure 2b). Only 3.4% of European vegetated land exhibited significant browning (\(p<0.05\)) according to the GLASS LAI product. Approximately 23.7% of European vegetated land exhibited significant greening (\(p<0.05\)) (Figure 2d) with an average greening rate of approximately 0.0046 m\({}^{2}\) m\({}^{-2}\) yr\({}^{-1}\) or 0.62% yr\({}^{-1}\) (i.e., annual linear trend relative to the year 2001 base; the same definition of relative changing rate for annual trend hereafter) by the LAI (\(p<0.001\)) (Figure 3a). Figure 1: Spatial and interannual dynamics in FGM GPP. (**a**) Sixteen-year averages of European terrestrial GPP (g C m\({}^{-2}\) yr\({}^{-1}\)) in contemporary climate simulated by FGM for vegetated surfaces at a spatial resolution of 500 m \(\times\) 500 m. (**b**) Interannual dynamics of total GPP (Pg C yr\({}^{-1}\)) for different vegetation types. Nonvegetated areas are masked out. The annual total GPP calculated by BEPS, MODIS, GLASS, VPM, and GOSIF also showed significant positive trends and the annual GPP exhibited increasing trends ranging from 0.47% yr\({}^{-1}\) to 0.92% yr\({}^{-1}\). Thus, the interannual trend of GPP estimated by the FGM was reasonable compared with other models. In addition, the GPP annual trend estimated by the FGM (0.55% yr\({}^{-1}\)) was very close to the greening rate (0.62% yr\({}^{-1}\)) (Figure 3a).