Quantifying landscape connectivity gaps between protected area and natural habitat

Protected areas are crucial for safeguarding biodiversity and mitigating significant threats. However, the effectiveness of protected areas has been debated, particularly regarding their anthropogenic protection's impact on species migration within the current protected area network. To address this issue, we calculated the connectivity between landscape elements (e.g., Core, Patch, and Connector) in China based on the resistance theory, taking the Core with high habitat quality as a source. We found that the landscape connectivity of protected areas in China is 44% of that of the natural habitats (i.e., Core), indicating that the effectiveness of the connected network of protected areas in China requires improvement. Nevertheless, the planning of protected areas in the Yellow River Basin makes landscape connectivity higher than that of natural habitats. In addition, the species abundance in protected areas is lower than that of natural habitats, overall, species abundance increases with habitat quality and landscape connectivity. Our results indicate that the previously protected area planning mainly focused on mammals while overlooking reptiles but reducing landscape connectivity gaps can enhance species abundance. The findings underscore the importance of incorporating landscape connectivity into the effectiveness evaluation system of protected area networks.