Linking supply-demand balance of ecosystem services to identify ecological security patterns in urban agglomerations

Ecological security patterns (ESP) is an effective approach to identify the priority conservation areas and maintain regional ecological security. The previous ESP studies only focused on the supply of ecosystem services (ESs), but ignored the supply-demand interaction of ESs. In this study, a novel large-scale ESP framework was proposed by introducing the supply-demand scarcity of ESs to revise identification of ecological sources. According to the scarcity theory "the severer ESs imbalance, the higher priority of protection", the ESs scarcity supply capacity (ESSSC) was reconstructed by combining ESs supply with two adjust factors of the urgency of regional eco-protection (UEP) and the priority of ESs type (PET). Finally, ecological sources integrating ESSSC and ecological sensitivity, ecological corridors, and ecological nodes were identified to establish a cross-regional ESP. The results show: (1) the reconstructed ESSSC approach significantly increased ecological sources areas of developed cities in urban agglomerations with the severer overall and structural imbalance, and effect of PET exceeds UEP; (2) appropriate allocation of key protection areas in regions with low supply but high demand and the priority protection of the severely imbalanced ESs types can alleviate environmental injustice; and 3) the extracted 160 ecological corridors and 16 ecological nodes effectively enhanced connectivity among ecological sources (36.2% of the study area), and formed a complete and connected ESP. The scarcity idea for regional coordination can guide the trans-administrative ecological decision making.