Assessing the carbon sequestration potential by mangroves in a coastal metropolitan region

Abstract

Coastal blue carbon refers to the carbon stored in coastal ecosystems such as mangroves, which sequester up to 40 times more carbon than terrestrial ecosystems. These ecosystems are crucial for climate mitigation but are often degraded by human activities, releasing stored carbon and increasing greenhouse gas emissions. One of the factors contributing to this degradation includes stilts houses built in flooded areas found in Brazilian territories, such as in the Baixada Santista Metropolitan Region. This study aimed to model and assess the potential spatiotemporal dynamics of carbon sequestration by mangroves in a coastal metropolitan region. Using the InVEST Coastal Blue Carbon model, we simulated three hypothetical management scenarios: conservation, restoration, and conversion. Land use and land cover maps (1991–2021) from MapBiomas were used as input data for the InVEST model. QGIS was used to apply the scenarios, with the conversion scenario expanding areas of stilt houses and the restoration scenario replacing stilt house areas in the region with mangroves. In the conservation scenario, no spatial edits were applied, and it was assumed that mangrove areas remained unchanged from the 2021 map onward. Under restoration, mangroves could sequester an additional 1300,000 tonnes of CO₂e over 50 years. conversion could lead to emissions that are approximately 2.03 times higher than those projected under the conservation scenario. Overall, our results can support local policies that promote conservation and restoration as nature-based solutions for climate change, while enhancing biodiversity, ecological functions, and the economic value of mangroves.