## 3 Results  
### Changes in Ecosystem Pattern  
During the first round of GGP from 2000 to 2010, the ecosystem composition and distribution in the GGP area (Table 3) indicated that the forest ecosystem was the largest ecosystem in the whole GGP area throughout the study period, occupying above 30%, followed by grassland, other types of land, cropland wetland, and artificial land. From 2000 to 2010, forest, wetland, and artificial land showed an increasing trend, while grassland, cropland, and other types of land declined. The artificial land increased dramatically by 22.38%; forest and wetland increased slightly by 0.77% and 1.03%, respectively; and cropland, grassland, and cropland decreased by 1.81%, 0.68%, and 0.41%, respectively. Forest, cropland, and other types of land changed more acutely in the first five years (2000-2005), while grassland, wetland, and artificial land changed more dramatically in the last five years (2005-2010). Forest in the GGP area was mainly distributed in the southern and northeastern subregions, while grassland was largely distributed over the northern subregions. Cropland was concentrated in the eastern plains and the Sichuan Basin (southwestern MHRSCHH), while the other types of land class were concentrated in the northwest Gobi desert throughout most of the ADRX and ASMRYY, and the western ASRNC. Wetland and artificial land were scattered across the whole area and were too small to be observed on the map (Figure 3a-c). The LULC transfer matrix (Table 4) demonstrated that the interconversion of cropland and forest played a primary role in ecosystem pattern change during 2000-2010, with 2.45% of cropland converted to forest and 1.11% of forest transferred to cropland. In addition, the transformations from cropland to artificial land, from grassland to forest, from cropland to grassland, and from grassland to cropland were also significant. The ecosystem transformation mainly took place in 2005-2010, since the transformed area of each ecosystem type was almost twice as much as that from 2000 to 2005. Forest, grassland, and cropland ecosystems were the major transfer direction and sources to each other, while wetland was mainly converted to cropland and grassland and was also mainly replenished from cropland, grassland, and other types of land. Artificial land mostly came from and transferred into cropland. Among all ecosystems, the dynamics of wetland were the most drastic: only 96.54%, 95.76%, and 93.56% wetland remained unchanged during 2000-2005, 2005-2010, and 2000-2010, respectively. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Year** & **Statistics** & **Forest** & **Grassland** & **W wetland** & **Cropland** & \
\begin{tabular}{c} **Artificial** \\ **Land** \\ \end{tabular} &
\begin{tabular}{c} **Other Types** \\ **Land** \\ \end{tabular} \\ \hline \multirow{2}{*}{2000} & Area (km\({}^{2}\)) & 2,233,481 & 1,970,441 & 194,734 & 1,412,776 & 117,128 & 1,488,317 \\ \cline{2-8}  & Proportion (\%) & 30.11 & 26.57 & 2.63 & 19.05 & 1.58 & 20.07 \\ \hline \multirow{2}{*}{2005} & Area (km\({}^{2}\)) & 2,242,365 & 1,968,996 & 195,191 & 1,397,649 & 128,268 & 1,484,578 \\ \cline{2-8}  & Proportion (\%) & 30.23 & 26.55 & 2.63 & 18.84 & 1.73 & 20.02 \\ \hline \multirow{2}{*}{2010} & Area (km\({}^{2}\)) & 2,250,770 & 1,956,982 & 196,733 & 1,387,172 & 143,346 & 1,482,206 \\ \cline{2-8}  & Proportion (\%) & 30.35 & 26.38 & 2.65 & 18.70 & 1.93 & 19.98 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The ecosystem composition and distribution in the Grain for Green Program (GGP) area in 2000, 2005, and 2010. Figure 3: Spatial pattern of ecosystem distribution and transformation in the Grain for Green Program (GGP) area. (**a–c**) are the ecosystem distributions in 2010, 2005, and 2010, respectively; (**d**) is the ecosystem transformation from 2000 to 2010.