Revealing spatio-temporal differentiations of ecological supply-demand mismatch among cities using ecological Network: A case study of typical cities in the “Upstream-Midstream-Downstream” of the Yellow River Basin

The ecological supply–demand mismatch resulting from rapid urbanization stands as a core challenge affecting regional sustainability. This study constructed ecological supply–demand networks from the perspective of the circulation of ecological processes flow within regions, and proposed a novel supply–demand relationships evaluation index system. The case study results of six typical cities in the 'Upstream-Midstream-Downstream' of the Yellow River Basin demonstrate that our proposed evaluation index system can more accurately reveal the dynamic interaction of ecological resources within the urban area and the degree of supply–demand mismatch. Additionally, we found that the supply–demand relationship in upstream cities is better than that in midstream and downstream cities, with downstream cities exhibiting the worst performance. Furthermore, over the past 20 years, the supply–demand relationships of all six cities have consistently deteriorated, with the maximum decline reaching 39.8 %. Social development factors have driven imbalance changes in ecological resource allocation and spatial connectivity between the supply and demand sides, serving as a key factor in driving the deterioration of urban ecological supply–demand relationships. Lastly, this study proposes a partitioned protection strategy adaptable to both the basin and individual cities. This study holds significant importance for optimizing the allocation of ecological supply–demand resources and protecting ecosystems in different watershed segments.