Spatial Variation of Anthropogenic Pressures and Their Impact on the Structure and Carbon Sequestration Ability of Rhizophora racemosa Stands in a Peri-Urban Mangrove of Côte d’Ivoire, West-Africa

Abstract

Aims: To evaluate the spatial variation of anthropogenic pressures and their impact on the stand structure and carbon stock of Rhizophora racemosa in the peri-urban mangroves of Abouabou Bay, Côte d’Ivoire. Study Design: Descriptive and comparative ecological study based on a spatially stratified sampling design. Place and Duration of Study: Amangoua-Koi village (southeastern Abouabou Bay, Port-Bouët municipality, Abidjan, Côte d’Ivoire), surrounding the Felix Houphouet-Boigny international airport, from February to June 2025. Methodology: Seven coastal sectors of the Amangoua-Koi village (Aero-Canal, Amangoua-Koi, Darakodji, Agnikro, Abbeykro, Abouabou, and Kamboukro), representing a gradient of human disturbance, were surveyed. A total of 18 sites (each 1 ha) were established to inventory infrastructures, pollution sources, and Rhizophora racemosa structural attributes. Vegetation data were collected in 112 plots (200 m²), including tree height, diameter at breast height (DBH), stem density, and basal area. Total biomass of R. racemosa trees was estimated using a species-specific allometric equation, and carbon stock was derived with a conversion factor. Chi-square tests assessed spatial variation in disturbance types, and generalized linear models (GLMs) or ANOVAs tested differences in structural and functional metrics among sectors. Results: Significant spatial heterogeneity in anthropogenic pressures was observed (χ² = 84.99, P < .001). Darakodji showed the highest pollution levels; Kamboukro and Aero-Canal exhibited the lowest. R. racemosa was absent from four sectors and sparse in Agnikro. Kamboukro and Aero-Canal displayed superior stand attributes, with mean tree heights up to 10.12 ± 4.34 m and DBH values of 16.73 ± 8.96 cm. Stem density reached 18.44 ± 18.40 ind. 200 m⁻² in Kamboukro. Biomass ranged from 0 to 5,951.73 ± 6,146.82 kg 200 m⁻², and carbon stocks from 0 to 139.87 ± 144.35 t C ha⁻¹. Tidal connectivity and low disturbance were key to high carbon storage. Conclusion: Localized human disturbance strongly influences structure of R. racemosa stands and carbon dynamics. Conserving intact stands and restoring degraded sectors through hydrological restoration and participatory management are essential for sustaining ecosystem services and supporting national climate commitments.