DYNAMICS OF FOREST FORMATIONS IN UPPER-CASAMANCE (SENEGAL) FROM 1965 TO 2018, IMPACTS ON AGRO-SYLVO-PASTORALS ACTIVITIES AND ADAPTATION STRATEGIES ; DYNAMIQUE DES FORMATIONS FORESTIÈRES DE LA HAUTE-CASAMANCE (SÉNÉGAL) DE 1965 A 2018, INCIDENCES SUR LES ACTIVITÉS AGRO-SYLVO-PASTORALES ET STRATÉGIES D’ADAPTATION

The forest landscapes of southern Senegal, particularly Upper-Casamance, are increasingly subject to deforestation. The result is a strong tendency to "savanisation" and anthropization, hence the major concern of the Senegalese authorities to take charge of the problem. Faced with such a situation, the study of the dynamics of forest formations in Upper-Casamance becomes relevant for a sustainable management of forest resources. This study aims to map and quantify the evolution of forest formations between 1965 and 2018, and to analyze the main determinants of dynamics and impacts on agro-sylvo-pastoral activities, wildlife and woody flora.The methodological approach is based on the processing and analysis of aerial (Corona 1965) and satellite images [Landsat (TM 1987, ETM+ 1999, TM 2010 and OLI-TIRS 2018), Sentinel 2 (MSI 2018) and MODIS-NDVI (2000 to 2018)]. It is also based on the processing and analysis of hydro-climatic data and the collection of field data (field observations, GPS point surveys, household surveys and population perception).The results showed a significant savanisation and development of agricultural land. Indeed, forest formations lost 377 118.7 ha of their area between 1987 and 2018, or a deforestation rate of 62.04%. Woodlands and agricultural land increased by 263,172.4 ha (19.1%) and 147,178.2 ha (10.7%) respectively over the same period. Significant negative trends in NDVI indicated vegetation degradation along the Gambia border, along the Pata-Ndorna axis, in the centre of the study area and around Medina Gounass. On the other hand, significant positive trends (p0.1) indicate regeneration in the south. The percentage of significant positive trend (at the 10% threshold) is 1.8%; the significant negative trend is 2.1%. At the scale of classified forests and managed forests, great variability by domain, the geographic position and rainfall gradient was noted. This variability has shown that classified forests are much more affected by anthropogenic actions than managed ones. The ...