Characteristics of Mangrove Forests in São Tomé and Príncipe and The Potential for Restoration

Mangrove forests in Small Island States (SIDs) have not been fully incorporated into the global mangrove atlas. Here, we present a detailed analysis of the status and conditions of mangroves located in the Republic of São Tomé and Príncipe (STP). Mapping of mangroves was carried out using remotely sensed data and GIS. This was complemented by detailed ground truthing, GPS mapping, and community appraisals in all 19 mangrove sites in STP. Sampling was conducted in 24 square plots of 100 m ² that were randomly distributed along belt transects established perpendicular to the waterline. Within each plot, all trees with a stem diameter ≥ 2.5 cm were identified, counted, and position marked. Data on tree height (m), stem diameter (cm), and canopy cover (%) were collected, from which basal area (m ² ha ^− 1 ), stocking rates (stems ha ^− 1 ), and biomass carbon (Mg C ha ^− 1 ) were derived. Mangrove forests in STP are estimated to cover approximately 180 ha, with 97.1% of these occurring on São Tomé Island and the rest on the Island of Príncipe. There are six mangrove species in STP; dominated by Rhizophora racemosa G. Mey., R. mangle L., and Avicennia germinans (L.) L.. The stocking rates of mangroves in STP ranged from 400 to 2,880 stems ha⁻¹ (mean: 2,170.0 ± 366.0 stems ha⁻¹) with a basal area of 25.0 ± 3.9 m ² ha⁻¹ (range: 1.5 to 30.2 m ² ha⁻¹), and standing biomass of 240.1 ± 38.3 t ha⁻¹ (range: 11.1 to 315 t ha⁻¹). Together with below-ground biomass, mangroves in STP have a biomass carbon of 157.9 ± 24.9 Mg C ha⁻¹. Assuming a sediment carbon of 780.2 Mg C ha ^− 1 for Central African mangroves, the total ecosystem carbon of mangroves in STP is estimated at 938.1 Mg C ha ^− 1 (range: 701.1 to 1,123.2 Mg C ha ^− 1 ). Localized overexploitation of mangrove wood products for firewood and tannin extraction was witnessed in peri-urban mangrove sites at Praia das Conchas, Água Ize and Diogo Nunes, where natural regeneration was inadequate to support forest recovery. Other important threats to the mangroves were coastal development and waste disposal. These findings revealed spatial variation in mangrove distribution across STP, as well as identifying sites for targeted restorations. The study provides baseline data and information for exploring nature-based enterprises, including mangrove ecotourism and blue carbon.