The Mangrove Forest of Quirimbas National Park Reveals High Carbon Stock Than Previously Estimated in Southern Africa

Mangrove forests are known to store large amounts of carbon and provide several essential ecosystem services. Although mangrove forests vary across tropical and subtropical regions, forest conservation mechanisms have recognised the role of mangroves in climate change mitigation. Nevertheless, little about the total C stock in mangrove forests on the southern African coast has been reported. This is particularly true in Mozambique, where the coastline is covered with highly diversified mangrove forests, and there is still a lack of reports about its C stocks in mangrove forests. This work aims to quantify the above- and below-ground carbon stocks, and describe mangrove structure and species composition in the Quirimbas National Park (QNP), northern Mozambique. Based on a random sampling design, we established 41 circular plots. In each plot, we assessed alive trees, standing dead trees, litter, pneumatophores, woody debris, soil organic carbon (SOC) and natural regeneration, and C stock was quantified. We employed Parametric and Non-parametric statistical tests to check the differences between vegetation and soil parameters. Our study recorded six tree species in the mangrove forest of QNP with a stem density of 1222 ± 123 stem ha− 1 and 16.1 ± 2.1 m2 ha− 1 of basal area. The Importance Value Index indicated that Rhizophora mucronata is the most abundant, frequent, and dominant, while Xylocarpus granatum is the rarest in the area. The mangrove of QNP stores about 306.1 ± 49.4 Mg C ha− 1 of SOC (0-100 cm), 72.6 ± 11.7 Mg C ha− 1 of above-ground carbon, and 32.0 ± 5.0 Mg C ha− 1 of root carbon stock. The total C stock stored in the QNP mangrove forests is 410.2 ± 66.1 Mg C ha− 1 comparable to the most extensive mangrove forest in southern Africa. This study can foster meaningful progress in understanding the carbon cycling in Mangrove ecosystems and its potential role on climate change mitigation in southern Africa.