## 3 Results
### Spatiotemporal Variations in the Different Land Cover Change Types
In terms of the four changed types, the area of artificial restoration of forest-grassland was 0.59 \(\times\) 10\({}^{6}\) km\({}^{2}\), accounting for 6.23%. The areas of the cropland reclamation, return of cropland to forest-grassland, and urbanization were 4.70 \(\times\) 10\({}^{5}\) km\({}^{2}\), 3.30 \(\times\) 10\({}^{5}\) km\({}^{2}\), and 1.94 \(\times\) 10\({}^{5}\) km\({}^{2}\), accounting for 4.96%, 3.48%, and 2.04% of the total area of all of the change types, respectively. Figure 8: Land cover maps of China for (**a**) 2000 and (**b**) 2018, spatial patterns of (**c**) the dominant land cover change types, and (**d**) the six land cover categories. From 2000 to 2020, the proportions of the different vegetation types were different in each region (Figure 9). Self-rehabilitation of forest-grassland occupied the largest proportion in the seven regions. This was particularly significant in SC, where it accounted for 65.51%, i.e., more than half of all the vegetation types. The high proportion of cropland maintenance in CC was also noteworthy, accounting for 29.54%. Compared with the other regions, the significant proportion of urbanization in EC suggests that this region developed rapidly from 2000 to 2020, which deserves more attention. Divergent Leaf Area and Carbon Sequestration Changes Associated with the Main Land Cover Change Types  
There were distinct differences in the leaf area and carbon sequestration among the different LUCC types (Table 4). Among the LUCC types, the self-rehabilitation of forest-grassland contributed the most to leaf area change in China (8.81 \(\times\) 10\({}^{5}\) km\({}^{2}\), 51.15%). Cropland maintenance, cropland reclamation, return of cropland to forest-grassland, artificial restoration of forest-grassland vegetation, and urbanization accounted for approximately 4.27 \(\times\) 10\({}^{5}\) km\({}^{2}\) (24.78%), 1.62 \(\times\) 10\({}^{5}\) km\({}^{2}\) (9.38%), 1.33 \(\times\) 10\({}^{5}\) km\({}^{2}\) (7.75%), 1.10 \(\times\) 10\({}^{5}\) km\({}^{2}\) (6.38%), and 9743.71 km\({}^{2}\) (0.57%), respectively. The largest contribution to the total carbon sequestration was the self-rehabilitation of forest-grassland 857.56 TgC (44.77%). Cropland maintenance, cropland reclamation, return of cropland to forest-grassland, artificial restoration of forest-grassland vegetation, and urbanization accounted for approximately \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**LAI Change**} & \multicolumn{3}{c}{**GPP Change**} \\ \cline{2-7}
**Vegetation Type** & \begin{tabular}{c} **Average LAI** \\ **(m\({}^{2}\).m\({}^{-2}\).yr\({}^{-1}\))** \\ \end{tabular} & \begin{tabular}{c} **Total Leaf Area** \\ **(10\({}^{4}\) km\({}^{2}\))** \\ \end{tabular} & \begin{tabular}{c} **Contr.** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Average GPP** \\ **(gc\(\cdot\)m\({}^{-2}\)yr\({}^{-1}\))** \\ \end{tabular} & \begin{tabular}{c} **Total Carbon** \\ **(TgC)** \\ \end{tabular} & \begin{tabular}{c} **Contr.** \\ **(\%)** \\ \end{tabular} \\ \hline \
\begin{tabular}{c} Returning cropland to \\ forest–grassland \\ Artificial restoration of \\ forest–grassland \\ \end{tabular} & 0.02 & 13.35 & 7.75\% & 15.45 & 125.85 & 6.57\% \\ \hline
\begin{tabular}{c} Cropland maintenance \\ Cropland reclamation \\ Urbanization of \\ forest–grassland \\ \end{tabular} & 0.01 & 10.98 & 6.37\% & 8.16 & 108.81 & 5.68\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Annual mean and total changes in the LAI and GPP in the major vegetation transfer areas. Figure 9: Proportions of the areas of the main land cover categories in the seven different regions. 634.48 TgC (33.12%), 162.51 TgC (8.48%), 125.85 TgC (6.57%), 108.81 TgC (5.68%), and 26.24 TgC (1.37%), respectively. This phenomenon may be related to the area of each LUCC type in China. However, the results of the mean LAI per unit area show that there were positive changes in the LAI in each land use type.