Spatiotemporal changes and driving forces of ecosystem vulnerability in the Yangtze River Basin, China: Quantification using habitat-structure-function framework

Ecosystem vulnerability is the degree to which an ecosystem is susceptible to adverse effects of external disturbances. Exploring the pattern of ecosystem vulnerability and its driving mechanism is important for regional ecological protection and management. A little study has conducted the ecosystem vulnerability assessment from the perspective of multiple ecosystems characteristics, and the spatial heterogeneity impacts of climate change and human activities on ecosystem vulnerability variation need to be further explored. In this study, a habitat-structure-function framework was proposed to evaluate ecosystem vulnerability pattern of the Yangtze River Basin (YRB) in China from 1990 to 2018. Then, the spatial heterogeneity impacts of various factors on ecosystem vulnerability changes were examined utilizing the Geographically Weighted Regression model. Results show that the ecosystem vulnerability index (EVI) pattern in the YRB decreased from upstream to downstream. There was 63.85% of the basin area experiencing a decline in EVI from 1990 to 2018, which was primarily found in the source, southwest and north regions, while the southeast and east regions have suffered an increase in EVI. The impact of climate change on EVI changes increased as time scales increase, while, human activities were still the dominant factor leading EVI changes. Overall, areas with great impact of climate change on EVI variation were concentrated in the source region and upper reaches, while the remarkable impact of human activities occurred in the whole basin. The enhancement of climate warming and humid trend and the strengthen of ecological protection were benefit to the decline of EVI. The proposed framework can be extended to assess vulnerability in other areas or specific ecosystem types, and the findings are expected to provide policy recommendations for ecosystem conservation and management in the YRB.