Multifunctional ecological networks optimization in arid cities: a hierarchical framework

Optimizing ecological networks has become a vital approach to balancing the conflict between rapid urban development and environmental protection. However, for semi-arid regions like Lanzhou, creating a forward-thinking ecological network that effectively reduces ecological fragmentation remains a significant and unresolved issue. Here, we have proposed an innovative hierarchical framework tailored to the characteristics of semi-arid regions that integrates circuit theory and hydrological analysis to identify key ecological components, combined with kernel density estimation to predict future ecological sensitivity. The findings reveal significant ecological fragmentation in Lanzhou, exhibiting asymmetric source distribution, with southeastern clustering contrasting northwestern scarcity, primarily located in low-disturbance mountainous and forested areas. The ecological corridors predominantly consist of agricultural and forested landscapes, which effectively enhance habitat connectivity. The constructed ecological network incorporates prioritization levels to align with ecological conservation policies. This research focused on enhancing the current ecological network, in substantial improvements, as evidenced by increases in the α, β, and γ indices by 51.4%, 73.1%,15.0%, and the integration of 58 additional ecological stepping stone patches, which significantly mitigated the barrier effect. The framework in this research provides actionable strategies for eco-urban restoration, particularly for semi-arid areas facing the dual challenges of urbanization and ecological degradation.