Conserving habitat and ecosystem in protected areas amid increasing intensive human modification: A case study of China's Pan-Pearl River Delta

To address crises like habitat loss and environmental pollution caused by human modifications, protected areas have been established as a fundamental strategy, providing on-site protection for species and their habitats. Systematic evaluation of PAs is crucial for guiding decision-making, planning, and public perception. Besides assessing their effectiveness in safeguarding habitats and ecosystem services, considering the impacts of human activities is essential. A comprehensive assessment, encompassing ecological and social factors, enhances our understanding of the complex interactions between conservation efforts and human needs. Using the Propensity Score Matching (PSM) method, we evaluated the conservation effectiveness of PAs in the Six Provinces in China's Pan-Pearl River Delta Region, focusing on reducing human modification, sustaining ecosystem services, and improving habitat quality. The results indicated that PAs at higher elevations generally exhibit a lower degree of human modification than those at lower elevations. While the human modification score outside PAs in the SPPPRD increased by 82.67%, the scores within PAs increased by only 64.51%. Among the 188 PAs, 32 showed a decrease in ecosystem services, with 71.87% located in Hainan Province. The average Habitat quality of PAs in the SP-PPRD declined during the study period, although the number categorized as "Very High" increased from 135 to 140. After PSM matching and relative effectiveness evaluation, 27 PAs (14.36%) were categorized as "High Effective", 50.00% as "Medium Effective", and 8.86% as "Ineffective". Furthermore, the study suggests that PAs were often located in areas unlikely to face land conversion pressure even without the protection. However, many PAs in regions with high levels of human modification have seen an improvement in ecosystem services and habitat quality. Based on our research findings, we advocate the adoption of more resilient conservation strategies that carefully balance the preservation of nature with the promotion of sustainable social development.