Ecological Protection Redlines' Positive Impact on Terrestrial Carbon Storage in Hainan Island, China

The establishment of the ecological protection redline (EPR) in China plays a crucial role in safeguarding key ecological functional areas and sustaining biodiversity. Besides their significance, the impact of these redlines on regional carbon sequestration remains unclear due to current inconsistencies in their implementation and adjustment. This paper conducts a thorough analysis of the evolution of two EPR versions on Hainan Island and employs the InVEST model to assess the effects of two EPR areas on regional carbon storage between 2000 and 2020. Additionally, a spatial autoregressive model is integrated to explore the socioeconomic and environmental driving mechanisms behind changes in regional carbon storage, thereby revealing complex interactions between ecological protection policy adjustments and ecosystem services of carbon storage. Key findings include: (1) The 2022 EPR area has improved the management of ecological protection boundaries, permanent cultivated land, and urban development boundaries, outperforming the 2016 version, particularly in control of construction land and water resource management. (2) The EPR2022 exhibits higher carbon storage per area, indicating a more effective zoning system. The increase in carbon storage is primarily observed in transitions from cultivated land to forest, grassland to forest, and water bodies to grassland. (3) Elevation exhibits a relatively strong positive correlation with carbon storage within the EPRs, with high-altitude areas typically encompassing the core zones of tropical rainforest national parks that possess diverse vegetation and stable ecosystems, conducive to maintaining or increasing carbon storage. Evaluating the efficacy of the EPR in enhancing regional carbon storage is critical for refining management strategies and achieving carbon neutrality goals. Future strategies should incorporate a comprehensive analysis of ecosystem services of carbon storage into the EPR framework to enhance multiple ecosystem functions, thereby establishing a resilient and functionally stable ecological landscape. This research introduces an insightful estimation method crucial for developing more effective ecological protection policies and provides valuable insights for managing ecological protection areas globally.