IMPACT OF ANTHROPOGENIC ACTIVITIES (AGRICULTURE, MINING, URBANIZATION) ON VEGETATION AND SOILS IN MARITIME GUINEA (2002–2024)

Abstract

The sub-prefecture of Damakhania, in Maritime Guinea, is undergoing rapid landscape transformation driven by the The landscapes of the Damakhania sub-prefecture, in Maritime Guinea, are being rapidly reshaped by the combined effects of urban expansion, agriculture and climate variability. This study examines changes in vegetation and hydroclimatic conditions between 1986 and 2024, quantifies land-use/land-cover (LULC) change between 2002 and 2024, and explores possible trajectories up to 2100. Fifteen variables were analysed: seven Landsat-derived indices (NDVI, EVI, SAVI, MSAVI, NBR, NDWI and LST) and eight climatic and water-balance variables. Trends and change points were assessed with the Mann-Kendall, Sen's slope and Pettitt tests, and seasonal contrasts with Student's t-test and the Mann-Whitney test. LULC maps for 2002 (Landsat 5 TM) and 2024 (Landsat 8 OLI) were used to measure change and to build three prospective scenarios. EVI declined significantly (τ = −0.385; p < 0.001), whereas land surface temperature rose by about 0.23 °C per year (τ = 0.397; p < 0.001). The Pettitt test indicated significant inhomogeneity in the EVI, NBR and LST series, while precipitation, maximum air temperature and NDVI showed no significant trend. Over 22 years, wooded/shrub savanna and open forest lost 47.4% and 45.7% of their area, respectively, to the benefit of urban fabric (+203.4%), degraded areas and bare soil (+189.7%) and crops and fallow land (+33.5%). The scenarios suggest that, without conservation measures, natural vegetation could disappear before 2050. The observed degradation appears more closely related to human pressure than to an unfavourable rainfall trend, which calls for land-use planning that protects the remaining wooded areas.