Integrating two landscape connectivity models to quantify the priorities of wetland conservation and reclamation restoration at multiple scales: A case study in the Yellow River Delta

Abstract

Coastal wetlands have been globally fragmented by reclamation activities, leading to reduced connectivity, which play an important role in maintaining the integrity of ecosystem functioning. However, practical wetland management rarely considers the connectivity effects of reclamation. How to identify hot-spot targets for wetland protection and restoration aimed to improve wetland connectivity presents a big challenge in the decision-making process. Here, we integrated GIS-based graph theory model and circuit theory model to evaluate the influences of coastal reclamation on wetland connectivity and identify conservation priority and restoration priority at multiple (patch, corridor and key node) scales, respectively, in the Yellow River Delta (YRD), China. The results indicated that since 1980s, reclamation has significantly reduced the area and landscape connectivity of different wetlands in this delta, especially saline marshes. According to important contributions of individual patches to the overall landscape connectivity, 515.36 km2 of natural wetland and 430 km2 of reclaimed wetland were identified to be protected and restored primarily. Our models also showed that coastal reclamation increased the resistance of species movement among wetland habitats. Potential corridors crossing natural wetlands (674.4 km) and crossing the reclaimed wetlands (21.92 km) should be protected and restored. In addition, 83 key ecological nodes such as pinch points (9.96 km2) and barrier points (46.54 km2) should be given priority conservation and restoration, respectively. This work answers the question of where and how to protect and restore wetland hotspots to improve landscape connectivity. The idea of optimizing the replacement of patches, corridors and key ecological nodes in the YRD has guiding significance for wetland management and biodiversity conservation in other regions with poor data.