Translating Landscape Fragmentation into Benchmarks of Environmental Impact Assessments: Thresholds of Ecosystem Service Losses in Guanzhong Region, China

Rapid urbanization reshapes landscape structure and threatens ecosystem services, yet operational ecological benchmarks for environmental impact assessment remain limited. Focusing on China’s Guanzhong region, this study examines how landscape fragmentation influences the ecosystem service value (ESV) and identifies critical threshold points for planning and management, using land-use data from 1990 to 2020 combined with spatial and statistical analyses. The results show that urban expansion substantially increased landscape fragmentation, with patch density rising by 109%, and contagion declining by 83.7%. Although the total ESV showed partial recovery over the study period, the landscape pattern mediated approximately 62% of the total effect of land-use change on ESV, constituting the dominant transmission pathway. Three actionable thresholds were identified: patch density of 1.2 patches·km−2, the largest patch index of 18%, and contagion of 15%. Beyond these breakpoints, ESV loss accelerates sharply, with the most pronounced rate increase reaching 355.6%. These findings provide region-specific reference values to support environmental impact assessment, ecological zoning, and land-use regulation in rapidly urbanizing areas.