Wildfire Impacts on Species Composition, Land Use Dynamics, and Ecosystem Service Vulnerability in Northern Ghana’s Savanna Ecoregions

Abstract

Changes in fire regimes, climate change and land use practices threaten tree structural diversity and vegetation structure across spatial and temporal scales. Therefore, this study investigated the impacts of fire on the species dynamics, land cover changes and the vulnerability of tree ecosystem services in the northern savanna regions of Ghana, encompassing the Northern, Upper East, Upper West, Savannah, and North East regions. The study analyzed data collected between 2001 and 2022 using a combination of remotely sensed satellite data (MODIS NDVI, Sentinel-2 images) and field observation. Species composition was assessed through vegetation inventories, and statistical models, including regression analysis and multivariate techniques, were applied to determine fire-induced changes in tree structural diversity and land use patterns on 30m x 30m plots of land (30 in total), across ten (10) communities. Land cover classification and change detection were performed using supervised classification in QGIS. The results showed a clear-cut reduction in forest cover and increased shrubby savannah and agroforestry types driven by recurring fires and agricultural land conversion. Fire-prone areas, particularly rangelands and vegetation zones near settlements, accounted for over 70% of recorded fires, making them the most frequently affected by wildfires. The dominance of fire-adapted species, such as Vitellaria paradoxa (14%) and Parkia biglobosa (11%) of the total species recorded, was observed, whereas fire-sensitive species declined in areas with high fire frequency. The study also provided insights into the vulnerabilities of significant ecosystem services and products, such as water bodies, forests and farmlands that are ferociously threatened by fire. The findings stipulate the need to implement more comprehensive and complicated approaches to fire management, integrating human activities and fire and ecosystem services preservation within savannah ecosystems.