## 2 Materials and Methods
### Methods
#### 2.3.2 Model for Assessing the ESV  
This study refers to the equivalent factor table for the ESV in China established by [PERSON] [15] to conduct an assessment of the ESV.  
\[ESV=\sum(A_{i}\times VC_{i}), \tag{4}\]  
\[ESV_{i}=\sum(A_{i}\times VC_{ij}), \tag{5}\]  
in these equations, \(ESV\): the total ESV, \(A_{i}\): the land area of the \(i\)-_th_ category, \(VC_{i}\): the unit ESV coefficient of the \(i\)-_th_ land type, \(ESV_{i}\): the individual ESV in a research area, \(VC_{ij}\): the coefficient of the \(j\)-_th_ ESV for the \(i\)-_th_ land type, \(i\): the number of land use types, \(j\): the ES function.  
The biomass correction factor (1.74) of the study area was used to adjust the ESV coefficient [15]. Based on socioeconomic statistical data, the average grain yield and price for the years 2000-2020 were calculated to be 6209.089 kg/hm\({}^{2}\) and CNY 2.855/kg, respectively. The ESV equivalent for the Southern Jiangsu urban agglomeration was determined to be CNY 2532.42/hm\({}^{2}\). By utilizing Formulas (4) and (5), the ecosystem service value coefficients for the Southern Jiangsu urban agglomeration for the years 2000-2020 were obtained (Table 3).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Land Use** & **Unused Land** & **Forestland,** & **Water Area** & **Farmland,** \\
**Types** & & **Grass Land** & **Wait-Up Land** \\ \hline Grading index & \(1\) & \(2\) & \(3\) & \(4\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Land use grading index.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Classification of ES**} & **Farmland** & **Forest Land** & **Grassland** & **Unused Land** & **Water Area** & **Sum** \\ \hline Primary & Secondary category & (CNY/hm\({}^{2}\)) & (CNY/hm\({}^{2}\)) & (CNY/hm\({}^{2}\)) & (CNY/hm\({}^{2}\)) & (CNY/hm\({}^{2}\)) & (CNY/hm\({}^{2}\)) \\ \hline Supply & Food production & 5992.72 & 1112.62 & 3552.67 & 0.00 & 3525.13 & 14,183.14 \\ services & Raw material & 396.58 & 2555.72 & 1476.15 & 0.00 & 1013.48 & 5441.92 \\  & Water resource supply & 11,588.87 & 1321.92 & 6455.40 & 0.00 & 36,529.16 & 55,895.35 \\ \hline \multirow{4}{*}{Regulatory} & Gas regulation & 4891.12 & 8405.23 & 6648.18 & 88.13 & 3392.94 & 23,425.59 \\  & Climate regulation & 2511.66 & 25,149.60 & 13,830.63 & 0.00 & 10,090.69 & 51,582.57 \\ services & Environmental & 749.09 & 7369.73 & 4059.41 & 44.06 & 24,455.52 & 36,677.88 \\  & Purification & 11,985.44 & 16,457.95 & 14,221.70 & 132.19 & 450,511.67 & 493,308.96 \\  & Hydrological & & & & & & \\  & regulation & 44.06 & 10,233.89 & 5138.98 & 88.13 & 4097.96 & 19,603.03 \\ \hline Support & Maintenance of & 837.22 & 782.14 & 809.68 & 0.00 & 308.45 & 2737.48 \\  & Biodiversity & 925.35 & 9319.56 & 5122.46 & 88.13 & 11,236.35 & 26,691.85 \\ \hline Cultural & \multirow{2}{*}{Aesthetic landscape} & \multirow{2}{*}{396.58} & \multirow{2}{*}{4086.95} & \multirow{2}{*}{2241.76} & \multirow{2}{*}{44.06} & \multirow{2}{*}{8328.12} & \multirow{2}{*}{15,097.47} \\ services & & & & & & \\ \hline  & Sum & 40,318.68 & 86,795.32 & 63,580.70 & 484.71 & 553,489.55 & 744,645.26 \\ \hline \hline \end{tabular}
\end{table}
Table 3: ESV coefficients from 2000 to 2020.