Assessing the dynamic landscape ecological risk and its driving forces in an island city based on optimal spatial scales: Haitan Island, China

Since the construction of the 21st Century Maritime Silk Road, islands in China have undergone more rapid urbanization, commercialization, and tourism. The interactions between natural and anthropogenic processes, however, have severely disturbed island ecosystems. Therefore, it is crucial to understand these interactions and identify key areas for island ecosystem protection and restoration by assessing the spatiotemporal patterns of landscape ecological risk. In this study, we investigated the optimal spatial scale needed to analyze spatiotemporal changes in landscape ecological risk on Haitan Island from 2000 to 2020. The landscape index varied with the change in spatial size, and the optimal grid size and scale based on semivariogram analysis were 75 m and 500 x 500 m, respectively. The spatial patterns of land use and landscape ecological risk have significantly changed owing to urban development on Haitan Island, with large amounts of cropland and forest being replaced by impervious land. The overall threat level of landscape ecological risk has decreased, and lowest-risk areas have gradually become the dominant type in the region. However, the landscape fragmentation and degree of water loss is increasing, and the landscape ecological risk of offshore areas cannot be ignored. The spatial clustering characteristics of landscape ecological risk in each period were significant, and the hotspots in the spatial distribution of the landscape ecological risk index were mainly coastal areas. The impacts of human activities on regional landscape patterns and ecosystems are increasing in intensity, and population density and distance to urban centers are the main drivers. This study provides a theoretical reference for selecting an optimal scale of analysis for ecological risk assessment in island landscapes and can be used as a reference in island spatial regulation and environmental impact assessments.