## 2 Materials and Methods
### Methodology
#### 2.2.2 Adjustment of Ecosystem Service Value  
ESs are fundamentally dependent on ecological processes, and the latter are not only spatial but also temporal [62]. The ESV calculated above is related to the land use type,which is static and cannot reflect the ecosystem dynamics [36; 63]. Meanwhile, this method focuses on the ESs rather than ecological processes, making the results unable to accurately reflect the differences in the types and qualities of ESs provided in different regions [64]. In fact, the ESV is also affected by various driving factors, including the precipitation and vegetation index, so it is necessary to adjust the value according to the heterogeneity of the ESs. We adjusted the ESV by calculating the spatial distribution of the important ESs to make the results more in line with reality. According to the \"Table of equivalent value per unit area of ecosystem services in China\", seven types of ESs including food production, raw material production, gas regulation, climate regulation, hydrological regulation, soil conservation, and maintenance of biodiversity were selected for evaluation. * Grain production Grain production is critical for the survival of humanity and dominates much of the world's terrestrial and marine environments [65]. Related studies show that there is a positive correlation between soil fertility and soil organic matter content [66; 67]. In this study, the content of soil organic matter was used to characterize the supply capacity of grain production. The soil organic matter content data in Sichuan Province were obtained from the HWSD, and the missing data were supplemented by kriging interpolation. * Raw material production Ecosystems convert solar energy into biological energy through photosynthesis and produce wood and other raw materials for human use [68]. Net primary production (NPP) represents the amount of energy used by plants for storage, growth, and reproduction and can be used as an index to measure the capacity of raw material supply [69]. In this study, NPP was calculated by the MuSyQ NPP algorithm [70]. The formula is as follows: \[NPP=GPP-R_{a}\] (7) where \(NPP\) represents the total amount of organic carbon that flows from the atmosphere into the plant, \(GPP\) is the gross primary production that represents the total amount of organic carbon fixed by plants through photosynthesis, and \(R_{a}\) is the autotrophic respiration, including the energy needed for plants to maintain biomass and growth. \[GPP=APAR\times\varepsilon\] (8) where \(APAR\) is the photosynthetically absorbed active radiation, which is directly related to \(NPP\), and \(\varepsilon\) is the light use efficiency calculated through the LUE model proposed by [PERSON] et al. [71]. \[APAR=FPAR\times PAR\] (9) where \(FPAR\) is the fraction of photosynthetically absorbed active radiation derived from the global land surface satellite (GLASS) dataset [72]. \(PAR\) is the photosynthetically active radiation and is calculated as follows: \[PAR=0.48\times SW_{surface}\] (10) where \(SW_{surface}\) is the downward surface solar radiation and was obtained from the ERA-Interim dataset. * Air quality regulation and climate regulation Ecosystems play an important role in climate regulation by sequestering greenhouse gases and removing harmful gases from the atmosphere [73]. In this study, the InVEST carbon fixed model was used to calculate the quality of the service, and the formula is as follows: \[C=C_{above}+C_{below}+C_{soil}+C_{dead}\] (11)where \(C_{above}\), \(C_{below}\), \(C_{sail}\), and \(C_{dend}\) represent aboveground and underground carbon storage, soil carbon storage, and dead organic matter carbon storage, respectively. The carbon storage parameters of each part are obtained from Bao, Y. [74]. * Water conservation The ecological process in which ecosystems intercept precipitation, store and purify water, and maintain the normal functioning of the ecosystem is referred to as water conservation. It is essential for human survival and development [75].