## 4 Discussion  
### Spatial Development Plan  
In the twenty-first century, preparing cities for urban land use planning is a critical challenge, and the relevant authorities require guidance from the simulation results to define adaptation strategies and policies. In accordance with \"The Master Plan of Beijing (2016-2035)\" by The People's Government of Beijing City, natural resources such as green space, water system and wetland are important ecological barriers and great attentions is attached to the protection of this famous historical and cultural city, therefore, these zones are the planning constraints zones in this study. The development area is also obtained from the centralized construction area in the released \"planning map of two lines and three districts in the city\". Compared with the current land use situation, areas of the north of Daxing District, areas around Beijing Daxing International Airport and so on will be intensively constructed. According to \"The Master Plan of Beijing (2016-2035)\", the total scale of construction land (including urban and rural construction land, special land, external transportation land and some water conservancy facilities land) should be controlled within 3720 km\({}^{2}\) by 2020; the amount of cropland would be no less than 1.66 million mu by 2020; the city's \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & \multicolumn{6}{c}{**Cold Spot (_p_ < 0.01)} \\ \hline \multirow{2}{*}{/km\({}^{2}\)} & \multirow{2}{*}{**Cropland**} & \multirow{2}{*}{**Forest**} & \multirow{2}{*}{**Grassland**} & \multirow{2}{*}{**Water**} & \multirow{2}{*}{**Wetland**} & \multirow{2}{*}{**Impervious**} & \multirow{2}{*}{**Bare Area**} & \multirow{2}{*}{**Total**} \\  & & & & & & & & \\ \hline Cropland & 3396.14 & 34.68 & 166.78 & 14.93 & 1.46 & 51.28 & 0.00 & 3665.27 \\ Forest & 170.65 & 4707.03 & 316.92 & 6.77 & 0.15 & 1.47 & 0.00 & 5202.99 \\ Grassland & 146.83 & 202.45 & 765.26 & 14.67 & 1.82 & 10.74 & 0.07 & 1141.84 \\ Water body & 30.12 & 2.22 & 9.05 & 48.43 & 2.91 & 2.67 & 0.02 & 95.42 \\ Weltland & 1.58 & 1.18 & 1.32 & 0.83 & 0.13 & 0.23 & & 5.29 \\ Impervious surface & 1305.30 & 37.92 & 183.51 & 5.26 & 0.13 & 708.79 & 0.01 & 2240.93 \\ Bare area & 2.08 & 0.11 & 1.50 & 0.09 & & 0.06 & 3.85 \\ Total & 5052.71 & 4985.60 & 1444.35 & 90.98 & 6.60 & 775.18 & 0.16 & 12,355.59 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Land use transfer matrix in cold spot (_p_ < 0.01) areas of the change of NPP from 2000 to 2020. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Hot Spot (_p_ < 0.01)} \\ \hline \multirow{2}{*}{/km\({}^{2}\)} & \multirow{2}{*}{**Cropland**} & \multirow{2}{*}{**Forest**} & \multirow{2}{*}{**Grassland**} & \multirow{2}{*}{**Water Body**} & \multirow{2}{*}{**Impervious**} & \multirow{2}{*}{**Total**} \\  & & & & & & & \\ \hline Cropland & 4.528 & 0.860 & 1.959 & 0.029 & 0.010 & 7.387 \\ Forest & 1.158 & 1148.492 & 21.816 & 0.196 & & 1171.661 \\ Grassland & 0.842 & 20.721 & 43.427 & 0.217 & 0.002 & 65.209 \\ Wetland & 0.008 & 0.002 & 0.005 & 0.004 & & 0.019 \\ Water body & 0.041 & 0.104 & 0.008 & 1.864 & & 2.017 \\ Impervious surface & 1.153 & 1.687 & 1.408 & 0.004 & 0.094 & 4.347 \\ Bare area & 0.002 & 0.020 & & & 0.022 \\ Total & 7.731 & 1171.868 & 68.643 & 2.315 & 0.106 & 1250.662 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Land use transfer matrix in hot spot (_p_ < 0.01) areas of the change of NPP from 2000 to 2020.  
forest coverage rate would increase from the current 41.6% to 44% by 2020. In the actual land use in 2020, the area of impervious surface was 3475.76 km\({}^{2}\); the area of cultivated land was 3902.51 km\({}^{2}\) (5.85 million mu); and the area of forest land was 7388.60 km\({}^{2}\) (45.07%). The current regional development met the planning requirements, that is to say, the future development guidance of this study can refer to the land development planning. From 2000 to 2010, the NPP value of vegetation in Beijing fluctuated greatly (Figure 5).