Ecological Health Index (EHI), Ecological Risk Index (ERI), Ecosystem Service Index (ESsI) (2000/2005/2010/2015/2020)

All data are in raster format.Ecological Risk Index (ERI) is a composite indicator, comprising Drought Risk (SPEI + NDMI + SWI), Landscape Pattern Risk (Fragmentation Degree + Separation Degree + Fractal Dimension), and Human Activity Intensity (HAILS). ​The weights are determined using the entropy method, a standardized and robust approach.​​​Ecosystem Health Index (EHI)​​ employs the ​VOR Model, divided into Vigor (NDVI), Organization (a combination of landscape indices), and Resilience (InVEST Habitat Quality).

Notably, the weighting within the Organization component is highly detailed (landscape heterogeneity 0.4 / landscape connectivity 0.4 / landscape shape 0.2).​Ecosystem Service Index (ESsI)​​ focuses on five key services: Windbreak and Sand Stabilization (RWEQ), Water Yield (InVEST), Carbon Storage (InVEST), Soil Conservation (a modified InVEST version), and Water Conservation Capability (calculated using Terrain Index and Saturated Hydraulic Conductivity). ​The weights are determined via a combined AHP + Entropy Method approach, effectively integrating objective data with expert knowledge.​​​Ecological Security Index (ESI) is a coupled outcome of the preceding three indices:​​ ESI = (EHI × ESsI / ERI)1/2. ​This formula design is sophisticated, clearly embodying the logic that health and services provide positive contributions to security, while risk exerts a negative constraint.​​Particular attention is warranted for several key technical details:​Spatial Consistency:​​ All data was unified to a ​1km grid​ and the ​Albers projection​ to ensure precision in spatial analysis.​Landscape Risk Calculation:​​ Utilized ​Fragstats output at 5km grids.