Threshold-determined ecological risk early warning models are effective tools for conservation strategies guiding

Abstract

The early warning of ecological risk is the primary tool for curbing ecological degradation. There is a lag effect between the ecological risk and driving factors. Therefore, the threshold of driving factors can be used as an indispensable means of identifying potential threats to ecosystems. How to carry out ecological risk early warnings based on these thresholds requires further study. In this study, a comprehensive ecological risk assessment model (CERA) was established by combining landscape ecological risk assessment (LERA) and regional ecological risk assessment (RERA). The response thresholds of naturally and anthropogenically driven factors to CERA were determined using the constraint line method and elasticity analysis. Based on these results, an ecological risk early warning model was constructed. The results showed the following: (1) LERA showed an increasing trend, whereas RERA decreased between 2000 and 2020. (2) CERA showed a decreasing trend, but with large fluctuations. The CERA level showed a high center and low surroundings. (3) The non-linear relationship between CERA and drivers showed that CERA was higher in regions with a Digital Elevation Model <212.214, slope <1.036, rainfall <570.149, Gross Domestic Product <1.115, Normalized Difference Vegetation Index <0.576, population <251.927, cropland density <0.341, building density <0.056, and water density <0.341. (4) The WJL area showed a high-level of ecological risk warning, with 44.69% (22,791 km2) at Level IV and 23.8% (12,184 km2) at Level V warnings. Particularly, Level V warnings dominated the potential space by 51%. Areas like Tongyu and Da'an, exceeding 50% of Level V, require urgent attention. This study has elucidated the critical thresholds of CERA under various factors and, based on these thresholds, develops an ecological risk-warning model. This model can directly interpret the reasons for high-level warnings and provides essential support for broad ecological management and restoration efforts.