## 4 Discussion
### LUCs and the Response of ESV to These Changes  
LUC is a critical factor in assessing the impact of human activities on ESs and is one of the main drivers of ESs. This study employed a bivariate spatial autocorrelation analysis between LA and ESV, revealing that over the 20-year period, the [PERSON]'s I index for both was negative, with scatter plots primarily distributed in the second quadrant and the index increasing annually. This indicates a local spatial negative correlation between the intensity of LUCs and the ESV, with the correlation strengthening year by year. Additionally, the intensity of land use has been increasing annually, and the impact of LUCs on the ESV has become more severe over the years. Among them, the low-high pattern is mainly distributed in the areas of farmland and forest land, while the high-low pattern is mainly distributed in built-up land and water areas. This shows that the distribution of ESV grades is highly correlated with LUCs, and this aligns with the results obtained by [PERSON]'s [53] and [PERSON]'s research [55].  
Between 2000 and 2020, the built-up land area kept increasing, while the areas of farmland, forest land, and grassland persistently decreased, with farmland mainly being converted to built-up land. This trend is largely due to the fact that urbanization development often relies on the occupation of land types with flat terrain, such as farmland, indicating an acceleration of urbanization in the region and encroachment on the ecological space of other land types; this discovery aligns with [PERSON]'s research outcomes [56].  
Over the 20-year period, the total ESV of the study area exhibited a starting rise succeeded by a decline, with an overall downward trend, and the inflection point occurred in 2005. The reason for this pattern was that from 2000 to 2005, the increase in ESV from water bodies exceeded the decrease from other land types, while from 2005 to 2020, the ESV for all land types showed a decreasing trend. The land type contributing the most to ESV was water bodies, followed by farmland, forest land, grassland, and unused land. This is primarily due to the larger areas of water bodies, farmland, and forest land, along with their higher ESV coefficients.  
The territorial layout of ESV in the study area has largely persisted without change over the 20-year period, with a characteristic pattern of higher values in the eastern part and lower values in the western part. The eastern sections of the study area are characterized by areas of high value, including areas around Tai Lake and forest lands, which provide significant ESV with relatively smaller areas. This suggests that water bodies and forest lands should be designated as key areas and land types in ecological environmental protection efforts. The western portion of the study area contains areas that are considered to be of lower value, predominantly in farmland and built-up land regions. The gradual replacement of medium- and relatively high-value areas in the eastern part with relatively low values indicates that urbanization has accelerated in this region over the 20 years. The expansion of built-up land has incrementally encroached upon forest lands and farmland, leading to more intense human activities. This has resulted in a decrease in the regulatory and supportive service functions, resulting in a loss of ecosystem service value.