Evaluating the effectiveness of the ecological redline policy in conserving mangroves via assessment on coverage and carbon storage

Abstract

Mangrove ecosystems are famed for their crucial ecological functionalities in moderating global carbon cycling process. To safeguard these ecosystems, the Chinese government implemented the Ecological Redline Policy (ERP) in 2017. This study evaluated the effectiveness of ERP in protecting mangroves and enhancing their carbon storage potential using multi-temporal Landsat-8 OLI images via InVEST Carbon Storage and Sequestration model, and field surveys conducted in Guangdong Province, which hosts the largest mangrove distribution in China. The results revealed a total increase of 2094 ha in mangrove area, with approximately 65.2% of mangroves increase currently included in the ERP zoning plan. Within ERP zones, the mangrove increment was 1365.55 ha, with a lower expansion rate of 20.7% while the Non-ERP zones exhibited an increment of 729.32 ha at a higher expansion rate of 38.3%. Furthermore, around 80.0% of carbon storage in mangroves was managed within ERP zones, with no significant difference in carbon density between ERP and Non-ERP zones, though both groups showed an overall increase in carbon density by 2021 compared to 2013. It is suggested that the ERP zone not only enhances carbon storage but also improves other ecological traits of ecosystem. However, the current ERP appeared to fall short of fully meeting strategic needs, emphasizing the necessity of optimized planning to minimize tradeoffs between environmental quality and development.