Forest-savanna Boundary Dynamics in a Context of Climate Variability: The Case of the Belier Region in Côte D’ivoire
Kassi Alexis Kouamé *
Soil, Water and Geomaterials Sciences Laboratory (LSSEG), UFR of Earth Sciences and Mining Resources (STRM), Félix Houphouët-Boigny University, Abidjan, Côte d’Ivoire.
Tchimou Vincent Assoma
University Center for Research and Application in Remote Sensing (CURAT), UFR of Earth Sciences and Mining Resources (STRM), Félix Houphouët-Boigny University, Abidjan, Côte d’Ivoire.
Aimé Koudou
Department of Earth Sciences, UFR Environment, Jean Lorougnon Guédé University, Daloa, Côte d’Ivoire.
et Koffi Fernand. Kouamé
University Center for Research and Application in Remote Sensing (CURAT), UFR of Earth Sciences and Mining Resources (STRM), Félix Houphouët-Boigny University, Abidjan, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
Climate variability may influence vegetation dynamics at the forest-savanna boundary, but the temporal relationship between rainfall variability and land-cover change in the Belier region remains insufficiently resolved. This study assessed rainfall variability and forest-savanna boundary dynamics in the Belier region of Côte d’Ivoire. Mean annual rainfall data were analysed for the 1981–2020 period using the rainfall anomaly index, while Landsat imagery for 1988, 2000, and 2020 was used to map land-cover change through supervised classification. The climate analysis indicated an overall decline in rainfall, with deficits of approximately 16%. The decline was particularly pronounced during the 1991–2008 period, when rainfall anomaly indices shifted predominantly towards negative values. From 2009 onwards, precipitation showed a slight recovery. Land-cover analysis revealed forest degradation in favour of savanna between 1988 and 2000, followed by forest regeneration at the expense of savanna between 2000 and 2020. The correlation analysis indicated a strong positive relationship between rainfall and forest area and a strong negative relationship between rainfall and savanna area. These results suggest that the direction of forest-savanna boundary change broadly corresponded with rainfall trends during the study period. However, anthropogenic pressures, reforestation and conservation measures, and plantation fallowing may also have contributed to the observed vegetation dynamics. The findings therefore support a cautious interpretation of forest-savanna changes as outcomes of interacting climatic and human influences.
Keywords: Climate variability, rainfall anomaly index, land-use and land-cover change, remote sensing, Landsat, vegetation dynamics, forest regeneration