## 3 Results  
### Spatiotemporal Changes Analysis of ESV in Sichuan Province  
This study focuses on the years 2005, 2010, 2015, and 2018 to analyze ecosystem service values in Sichuan Province (Table 4). As indicated in Table 4, the total ecosystem service values for these years were CNY 10,267.17, 10,318.35, 10,290.12, and 10,310.43 \(\times\) 10\({}^{8}\), respectively. These figures display a fluctuating upward trend, marking a total increase of CNY 4.326 \(\times\) 10\({}^{8}\). Upon examining specific land use types, the ecosystem service value of farmland decreased by 3.87%, while that of grassland decreased by 2.12%. Notably, the value of ecosystem services for construction land plummeted by 80.46%, resulting in a total decrease of CNY 12.707 \(\times\) 10\({}^{8}\) for these three categories. Conversely, woodland, watersheds, and unutilized land experienced increases of 2.74%, 1.28%, and 25.35%, respectively, contributing to a total increase of CNY 17.033 \(\times\) 10\({}^{8}\). This upward trend in ecosystem service value was predominantly driven by expansions in woodland and watershed area. Upon analyzing the impact of various land use types on ecosystem service value in Sichuan Province, it becomes evident that forest land and grassland make the most significant contributions.  
Based on the coefficients derived from Formula (6) and Table 2, the ecosystem service value assessments for Sichuan Province in 2005, 2010, 2015, and 2018 were computed. Employing the best natural breakpoint method, the results were categorized into five grades: lowest ESV, lower ESV, medium ESV, higher ESV, and highest ESV, respectively (Figure 3).  
As illustrated in Figure 3, regions with low ESV designations were predominantly clustered in the eastern part of Sichuan Province, with the lowest areas concentrated around Chengdu and its neighboring counties. This area constitutes the economic and cultural core of Sichuan Province, characterized by low altitude, flat terrain, high population density, numerous cities, and a high level of urbanization. Consequently, the overall Ecosystem Service Value (ESV) for this region remained low. In contrast, high-ESV areas are concentrated in the Western Sichuan Plateau, characterized by high altitude, favorable ecological conditions, sparse population, and low urbanization levels, resulting in significantly higher ESV. Analyzing the patterns of change from 2005 to 2018 reveals that the low-ESV regions in the eastern part of Sichuan Province have generally expanded in the direction of Guangzhou,  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Land Use Type**} & \multicolumn{4}{c}{**ESV (CNV 10\({}^{8}\))**} & \multicolumn{4}{c}{**2005–2018**} \\ \cline{2-7}  & **2005** & **2010** & **2015** & **2018** & **The Change in ESV** & **The Change Rate of ESV** \\ \hline Farmland & 735.88 & 729.12 & 721.01 & 707.37 & –28.51 & –3.87\% \\ Woodland & 5937.46 & 6001.73 & 6027.07 & 6100.25 & 162.79 & 2.74\% \\ Grassland & 3112.12 & 3080.63 & 3061.01 & 3046.05 & –66.07 & –2.12\% \\ Watershed & 518.42 & 554.66 & 542.95 & 525.03 & 6.61 & 1.28\% \\ Construction land & \(-\)40.38 & \(-\)51.15 & \(-\)66.10 & \(-\)72.87 & –32.49 & –80.46\% \\ Unutilized land & 3.67 & 3.36 & 4.18 & 4.59 & 0.93 & 25.35\% \\ All & 10.267.17 & 10,318.35 & 10,290.12 & 10,310.43 & 43.26 & 0.42\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: The structure of and change in the ESV of various land use types in Sichuan Province from 2005 to 2018.  
Figure 3: ESV in Sichuan Province from 2005 to 2018.  
Bazhong, and Dazhou, forming a 'C'-shaped trend. Addressing the rising trend of low ESV in the eastern part of Sichuan Province while maintaining the high-ESV trend in the western region poses a significant challenge in the ecological construction and governance strategies of Sichuan Province.