Effects of Climate Variability on Vegetation Dynamics in Upper Guinea: An Approach Based on NDVI, Precipitation, and Temperature Indices

Upper Guinea, a transitional zone between the Sahelian climate and forest influences, is particularly exposed to the impacts of climate change, with an intensification of climatic extremes. This study aims to investigate the relationship between climate variability (temperature and precipitation) and vegetation response, as measured by the NDVI index, over the period from 2012 to 2021. The data were obtained from reliable satellite sources such as MODIS (NDVI), ERA5 (temperature), and CHIRPS (precipitation). The methods employed include monthly climatology, linear trend analysis, standardized anomaly assessment, and Pearson correlation analysis. The results reveal a pronounced seasonality of NDVI, peaking in September to October, reflecting a biological lag following rainfall. Temperature shows a significant upward trend (+0.091˚C/year), while precipitation remains highly variable without a clear trend. NDVI displays a moderate but significant positive trend (+0.009 NDVI/year), particularly marked after 2015. A strong correlation with temperature (r = 0.72) contrasts with the weak influence of precipitation (r = 0.03). The study highlights the key role of temperature in ecological dynamics and the relative resilience of vegetation, while emphasizing that this resilience remains dependent on sufficient water availability. It concludes by recommending rigorous climatic and ecological monitoring to support adaptation strategies, sustainable management, and food security in West Africa.