# The Ongoing Greening in Southwest China despite Severe Droughts and Drying Trends
## 3 Results
### The Impact of Drought Events on Vegetation in SWC from 2009 to 2012  
Different degrees of drought have obvious differences in the impact of vegetation. In heavy drought areas, ADT showed a different degree of decline, compared to BDT for the three vegetation indicators (Table 2 and Figure 6); and the change trends of LAI, EVI, and GPP decreased by 2.5 \(\times\) 10\({}^{-3}\) m\({}^{2}\)/m\({}^{2}\), 1.2 \(\times\) 10\({}^{-3}\), 3.09 gC/m\({}^{2}\), respectively. In terms of long-term trends, drought events had not changed the greening trend of vegetation. The anomalies of LAI, EVI, and GPP after 2012 were 0.0629 m\({}^{2}\)/m\({}^{2}\), 0.0187, and 70.86 gC/m\({}^{2}\), respectively. In other words, drought events in the SWC affected the growth of vegetation only during the drought period, but had little impact on the long-term trend. In slightly arid areas, for LAI and EVI, after a slight decrease in ADT, LTT quickly recovered to the pre-drought level. In contrast, the recovery of GPP is not obvious. This may be related to the changes in solar radiation in the area. In the GPP algorithm by [PERSON] et al., solar radiation as the dominant influence significantly affects GPP. For areas where drought had not occurred, vegetation greening was more obvious. The LTT of LAI and EVI was significantly higher than that of BDT, which indicates that the areas were experiencing continuous greening. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Area** & **LAI** & **Annual** & **EVI** & **Annual** & **GPP** & **Annual** \\ \hline \multirow{2}{*}{Heavy drought} & 1982–2016 & 0.0043 ** & 2000–2019 & 0.0027 ** & 1982–2016 & 5.69 ** \\  & 1982–2008 & 0.0069 ** & 2000–2008 & 0.0032 ** & 1982–2008 & 9.18 ** \\  & 1982–2012 & 0.0044 ** & 2000–2012 & 0.0020 ** & 1982–2012 & 6.09 ** \\ \hline \multirow{2}{*}{Slight drought} & 1982–2016 & 0.0084 ** & 2000–2019 & 0.0034 ** & 1982–2016 & 4.92 ** \\  & 1982–2008 & 0.0074 ** & 2000–2008 & 0.0035 ** & 1982–2008 & 6.26 ** \\  & 1982–2012 & 0.0067 ** & 2000–2012 & 0.0030 ** & 1982–2012 & 4.45 ** \\ \hline \Figure 7 shows the spatial change trend of LAI, EVI, and GPP. Similar to the annual changes, vegetation greening was evident throughout SWC. There was a positive trend in 88.7% of pixels in LAI and 97.1% of pixels in EVI. In addition, GPP also showed an increase trend, with a positive value accounting for about 77.4%. During the drought period, the increase trends of LAI, EVI, and GPP decreased in a large area, which indicates that the growth of vegetation has been damaged to a certain extent, so that it affected the change trend of vegetation during this period. The increasing area was mainly concentrated in the southeast, where no obvious drought was found (Figure 4). By comparing LTT and BDT, it could be found that the effects of drought on the long-term vegetation trends in different regions were not consistent. There was a very obvious negative value for LAI in the west, but there was no impact in the east. EVI and GPP were more consistent, except for the southeast part; they all showed obvious negative values, and these areas had experienced different degrees of drought. After the drought, the vegetation quickly recovered. Except for some pixels in the southwest, the LTT in most areas was higher than the ADT in three vegetation indicators. In summary, although the SWC has experienced four years of drought events, the long-term vegetation trends have not been significantly affected. Compared with BDT, the LTT of LAI, EVI, and GPP might drop slightly in different regions, but from the perspective of annual change trend, the vegetation was still greening.