Climate change and variability as drivers of vegetation dynamics in Bontioli Natural Reserve, West African drylands

Abstract

• Climate change threatens West African drylands’ vegetation, reduces ecosystem services and accelerates biodiversity loss • Extreme climatic events are main driven factors of vegetation degradation that reduces carbon sequestration potential • Holistic strategies promote long-term climate vegetation resilience and, address the challenges of preserving natural reserves • Enhance West African dryland natural reserve's resilience relies on regular vegetation monitoring with integrative climate mitigation strategies. Climate change significantly impacts vegetation dynamics and plant productivity by affecting temperature, rainfall and seasonal patterns. In dryland ecosystems such as the West African savanna, these changes accelerate biodiversity loss, and reduces carbon sequestration capacity. This study examines vegetation response to climate variability in the Bontioli Natural Reserve (BNR), within the West African savanna. Using the Normalized Difference Vegetation Index (NDVI) retrieved from Landsat imagery via the Google Earth Engine platform, coupled with high-resolution bioclimatic data from the climatologies at high resolution for the earth's land surface areas (CHELSA) we analysed the vegetation changes over the past three decades (1993 to 2023) employing Generalize Additive Modelling (GAM). Results indicate significant shifts in vegetation dynamics at a rate of 0.051 ± 0.043/year, with vegetation decline primarily associated with increased temperatures and reduced rainfall. The model (R² = 0.836, p < 0.001, deviance explained= 0.935, RMSE= 0.073) underscores that rising temperature and prolonged droughts are key drivers of vegetation stress, while intermittent rainfall events trigger only temporary recovery phases. Vegetation productivity peaks were recorded at rainfall levels around 250-300 mm, and temperatures between 26–28°C. Spatial analysis of NDVI with fractional vegetation cover (FVC) highlights an ongoing decline in dense vegetation across the BNR, emphazing the severe consequences of climate change. These findings revealed the critical role protected areas play in mitigating climate impacts by maintaining ecological integrity and promoting vegetation resilience. A safeguarding measure with climate smart policies can play a crucial role in improving the vegetation resilience to climate change effects. Conservationists and policymakers should focus on integrative adaptive long-term climate-resilient plant species. Addressing these challenges directly supports the achievement of SDG 13 and 15 across the broader West African Savanna region.