[Table 2]

2.4.2 Construction of a comprehensive urbanization index

The weight is determined based on the information provided by the entropy, which reflects the original information of the index and improves the objectivity of the evaluation, depending on the degree of variation of each index (Liu, 2018). The detailed calculating steps of the weight for each indicator could be found in appendix, which are implemented with the help of Stata 16.

2.5 Measuring ecosystem health

Terrestrial ecosystem health can illustrate the quality of the regional ecosystem directly and comprehensively, which mainly includes three elements: vigor, organization and resilience (Costanza, 1992; Li, 2021). The EHI was calculated by the Eq.7 (Peng, 2015).
EHI =\(\sqrt[3]{V\ \times\ O\ \times\ R}\) (7)
where EHI is ecosystem health index of spatial entities; V, O, and R refer to ecosystem vigor, organization, and resilience of spatial entities, respectively.
Ecosystem vigor is simply a measure of its activity, metabolism or primary productivity. In this paper, it was characterized by NDVI referring to other studies (Peng, 2017).
Ecosystem organization conveys the structure stability and complexity of regional ecosystem. With reference to the research of Wu (2021), organization levels were measured by landscape indexes through subjective assignment method, and calculated by Fragstats 4.2 based on land use type. The formula was as follows:
O = 0.5 × SHDI + 0.25 × AI + 0.25 × COHESION (8)
where O denotes the value of ecosystem organization, SHDI, AI and COHESION are Shannon’s Diversity Index, Aggregation Index and Patch Cohesion Index, respectively.
Ecosystem resilience connotes its ability to maintain the ecosystem structure and function in the presence of stress. And the terrestrial ecosystem resilience could be expressed indirectly through land use change. The summation of area-weighted ecosystem resilience coefficients (ERC) for all land use types were used to measure ecosystem resilience. Based on expert knowledge and related references (Peng, 2017), the resilience coefficients of the six major land use types were shown in Table 3. Ecosystem resilience was calculated as follows:
\(R=\sum_{i=1}^{n}{\text{Ai}\times\text{ERC}_{i}}\) (9)
where R stands for ecosystem resilience, n represents the number of land use types, Ai represents the area ratio of land use type i, ERCi denotes the ecosystem resilience coefficient of land use type i.