Assessing ecosystem change and mitigating ecological risk in Qinghai-Tibet integrated transport corridor

• Highway and railway influence corridor ecosystem across patterns, processes, services, and risks. • The area within 1 km of roads exhibits the most dramatic ecological pattern changes. • The influence threshold of roads on macro ecological changes is 4-6 km. • Cadmium and lead accumulate in the upper soil layer within 30m from roads. • Grassland and soil ecological risks are generally manageable, and forest greening is remarkable. The ecological impacts of transportation infrastructure have received increasing attention; however, research on the ecological impacts and potential risks caused by multiple roads in ecologically vulnerable areas remains insufficient. This study develops a macro-micro assessment framework synthesizing ecological patterns, ecosystem services, landscape ecological risk, and soil pollution risk to systematically quantify ecological changes and risk thresholds, and proposes mitigation strategies for Qinghai-Tibet Integrated Transport Corridor. Results indicate that since 2000, road networks have increasingly influenced ecological patterns and ecosystem services, with a transition from human-influenced to natural systems at 4-6 km from roads, while landscape fragmentation did not significantly exacerbate in the corridor. Highway and railway transportation brought heavy metal deposition such as Cd and Pb mainly in upper soil layer, while soil pollution risk confined primarily within 30 m from roads. It recommends delineating differentiated ecological redlines and establishing dual-layer pollution control zones. These findings provide scientific reference for ecological transportation construction in vulnerable areas.