# Simulating Ecological Functions of Vegetation Using a Dynamic Vegetation Model
## 3 Results
### Synergistic and Trade-Off Relationships among Vegetation Ecological Functions  
As shown in Figure 6, we overlapped the significant regions of the relationships between CS and WC (CSWC), SC and WC (SCWC), and CS and SC (CSSC), and obtained the regions where all three relationships are significant. During 2081-2100, the significant regions of the CS and WC trade-off relationship, the SC and WC synergistic relationship, and the CS and SC synergistic relationship were mainly distributed in the Liupan Mountain, Ordos Plateau and accounted for 9% of the total area in the LP (Figure 6b). During same period under the SSP585 scenario, the significant regions of the CS and WC synergistic relationship, the SC and WC trade-off relationship, the CS and SC synergistic relationship were mainly distributed in the eastern edge of Qilian Mountains, Mu Us Sandy Land and accounted for 3% of the total area in the LP (Figure 6c). In addition, compared with  
Figure 5: Spatiotemporal distribution during 2001–2020 and changes during 2081–2100 relative to 2001–2020 in the CS, SC, and WC of the Loess Plateau. Note: carbon stock function, CS; soil conservation function, SC; water conservation function, WC. (**a1**): the spatiotemporal distribution of the CS during 2001–2020; (**a2,a3**): the changes of the CS during 2081–2100 relative to 2001–2020 under SSP119 and SSP585 scenarios; (**b1**): the spatiotemporal distribution of the SC during 2001–2020; (**b2,b3**): the changes of the SC during 2001–2020 under SSP119 and SSP585 scenarios; (**c1**): the spatiotemporal distribution of the WC during 2001–2020; (**c2,c3**): the changes of the WC during 2001–2100 relative to 2001–2020 under SSP119 and SSP585 scenarios. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**SSP119 Scenario**} & \multicolumn{3}{c}{**SSP585 Scenario**} \\ \cline{2-7}  & **CS** & **SC** & **WC** & **CS** & **SC** & **WC** \\ \hline Min & \(-4.99\) & \(-398.4\) & \(-127.54\) & \(-0.05\) & \(-274.7\) & \(-214.79\) \\ Max & \(4.13\) & \(3866.04\) & \(167.45\) & \(14.63\) & \(4740.09\) & \(327.23\) \\ Mean & \(-0.32\) & \(89.55\) & \(29.58\) & \(5.14\) & \(135.57\) & \(46.3\) \\ Std & \(0.7\) & \(132.01\) & \(30.19\) & \(1.64\) & \(203.92\) & \(53.51\) \\ AR (\%) & \(47\) & \(4\) & \(8\) & \(<\)\(1\) & \(3\) & \(13\) \\ \hline \hline \end{tabular} Note: Min, Max, Mean, Std, and AR indicate the minimum, maximum, mean, standard deviation, and the ratio of functional decline area of the Loess Plateau, respectively. Carbon stock function, CS (IC-Ra\({}^{-1}\)); soil conservation function, SC (I-Ra\({}^{-1}\)); water conservation function, WC (mm).  
\end{table} 
Table 3: Spatial statistical information on the changes in the CS, SC, and WC of the Loess Plateau during 2081–2100 relative to 2001–2020. 2001-2020, the area with significant trade-offs between CS and WC would shrink under the SSP19 scenario and that with significant synergisms would expand under the SSP585 scenario during 2081-2100 (Figure S3(a1-a3)). Compared with 2001-2020, the area with significant synergisms between SC and WC would expand under the SSP119 scenario and that with significant trade-offs would expand under the SSP585 scenario during 2081-2100 (Figure S3(b1-b3)). Compared with 2001-2020, the area with significant synergistic relationships between CS and SC would shrink under both the SSP119 and SSP585 scenarios during 2081-2100 (Figure S3(c1-c3)). These results suggest that future climate change will vastly shift the trade-offs and synergies between ecological functions. Figure 6: Significant trade-offs and synergistic relationships between the ecological functions of vegetation during 2001–2020 and 2081–2100. Note: carbon stock and water conservation functions, CSWC; soil conservation and water conservation functions, SCWC; carbon stock and soil conservation functions, CSSC; \(\uparrow\)significant synergism; \(\downarrow\)significant trade-off.