Unraveling the Complex Relationship between Urbanization and Landscape Ecological Risk:Insights from Chinese Cities

Highly urbanized cities have undergone substantial land use changes driven by intensive human activities, leading to increasingly prominent ecological security challenges. This study employed landscape pattern indices to evaluate the landscape ecological risk (LER) across 275 prefecture-level cities in China from 2011 to 2019. We hypothesized that the mechanisms influencing LER vary according to the level of urbanization. An integrated panel threshold regression model was applied to examine this hierarchical influence and identify potential thresholds in the urbanization rate (UR). In addition, the spatial spillover effects of LER were investigated using a spatial panel econometric model. Our findings revealed an initial increase in LER from 2011 to 2013, followed by a notable stabilization between 2015 and 2019, with evident spatial heterogeneity. Using UR as the threshold variable, the normalized difference vegetation index, population density, and per-capita gross domestic product (PGDP) were found to exert nonlinear impacts on LER, which were consistent across multiple model specifications. A critical threshold was identified at a UR of 62.1%, beyond which the influence of PGDP on LER altered substantially. Spatial spillover effects of LER were also stronger in cities below this UR threshold, implying that highly urbanized cities may possess self-regulatory ecosystem mechanisms that mitigate LER. Based on the results, the development of secondary and tertiary industries, alongside the construction of infrastructure, could mitigate LER for low-urbanization cities. In highly urbanized cities, blue-green space planning should be strategically aligned with industrial transformation and upgrading, thereby bolstering urban ecological protection and contributing to long-term environmental sustainability.