Protection cost allocation significantly affects transboundary ecological networks construction

Equitable allocation of protection costs across jurisdictions is crucial to promoting the establishment of transboundary ecological networks (ENs). To explore the influence of cost allocation methods on transboundary ENs, this study took four cities surrounding Taihu lake as study case, and developed five allocation criteria under the targets of maximum protection areas (S1) and best revenue (S2), including allocating equally (Ae), allocating by economic development (Ed), source revenue (Er), source area (Ea) and global coordination (Gc), for example, “S1-Gc” represented global coordination under target S1, Morphological Spatial Pattern Analysis (MSPA) and least-cost paths (LCPs) methods were employed to identify ecological sources and corridors, respectively. Results showed S1-Gc and S2-Gc achieved the largest protection area (about 1800 km²) with the highest input cost, the patch and corridors numbers, corridor length and revenue in S2-Gc were the highest, and were 139 %, 163 %, 83 % and 105 % higher than those in S1-Gc, it indicated S2-Gc could provide more benefits to biodiversity. S1-Ed achieved the highest network structure index, while the protected area and revenue were 40.75 % and 22.27 % lower than those of S1-Gc, respectively. Results emphasized differences in allocating criteria could lead to varying protection outcomes, and no single strategy universally satisfies all objectives. Therefore, decision-makers should explicitly define priorities during scenario design based on input cost and its corresponding protection effects, it could promote stakeholders to contribute proportionally to conservation efforts. Results provide valuable insights for policymakers and practitioners in optimizing cost allocation strategies and designing effective conservation plans in multi-jurisdictional regions.