Burning questions: a geospatial analysis of fire regime change in Côte d’Ivoire, 1984-2014

Africa has been called the “burn center” of the planet because it is the continent where the greatest proportion of global fire occurs. This widespread yet poorly understood phenomenon holds the key to processes such as land cover change, vegetation change, and the emission of greenhouse gasses. To understand this role, better information about the distribution and drivers of fire is needed. Research in West Africa points to seasonal changes in vegetation burning over the past 30 years. In Côte d’Ivoire, fieldwork at the terroir scale in one savanna region indicates an increase in the proportion of early dry season fires related to the expansion of livestock raising. Since early dry season fires are generally less intense than late dry season fires, a shift toward early season burning will influence vegetation cover and greenhouse gas emissions. But are these shifts apparent at broader scales? How does cattle herding interact with other variables affecting fire? This research investigates the factors affecting fire seasonality at the country level in Côte d’Ivoire. I reconstruct a representative history of fire activity for Côte d’Ivoire using more than 5000 Landsat TM/ETM+ images over the period 1984 to 2014. Active fires are detected in each image using two indices based on the radiance of fire in the shortwave infrared portion of the electromagnetic spectrum. The work assesses the fire regime as represented by active fire in 896 locations covering Côte d’Ivoire. It also investigates the relationship of fire patterns with climate and land use/land cover variables using random forest regression. The independent variables show a strong relationship with fire regularity and a weaker, though important, relationship with timing and density of fires. The results reveal spatial and temporal patterns in fire seasonality over the past 30 years in Côte d’Ivoire. While I conclude that the timing of fire across Côte d’Ivoire has not shown a substantial linear trend over time, the seasonality, density, and regularity of fire has fluctuated over time and space. These variations are related to temperature, rainfall, and pastoralism, among other variables. Improving the understanding of fire regimes in Côte d’Ivoire can shed new light on ongoing debates regarding the impacts of increasing agricultural activity in West Africa on fire, vegetation, and climate change