[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.