Assessment of carbon sequestration by mangrove plantations in Casamance (Oussouye, Ziguinchor, Senegal)

Abstract

The mangrove ecosystem abounds in fish and wood resources exploited by local populations for cooking and house construction. This has resulted in a strong loss of mangrove surfaces whose causes are explained by the combined action of natural and anthropic factors. To minimize the regression of the mangrove in Casamance, the Oceanium Association has organized since 2006 reforestation campaigns of mangrove trees. To date, the effectiveness of carbon sequestration by mangrove plantations has never been evaluated in southern Senegal. The present study aims to estimate the produced phytomass (biomass) and the aerial carbon stock of mangrove plantations to promote mangrove restoration actions. Three study sites were selected, namely the communes of Oukout, Mlomp and Diémbéring, in the Ziguinchor region (Senegal). They polarize 24 plantations distributed in 8 villages of the study area. The characterization of the mangrove plantations was performed from May to July 2020 using 2.5 m x 2.5 m plots, arranged alternately on each transect set up by plantation. The overall amount of carbon sequestered in the plantations in 2020 was estimated at 0.155 tC/ha for stems, 0.389 tC/ha for leaves and 0.501 tC/ha for roots. These results correlated with plant height allowed the development of a regression model to assess the total carbon stock in mangrove plantations. This model explained 81% of the total carbon stock in 7–10-year-old plantations. Results from this study suggest that mangroves can be dynamic and promising areas for climate change mitigation.