Fire seasonality changes in Côte d’Ivoire revealed through Landsat imagery

Abstract:

Fire plays a significant role in the savanna systems of West Africa, where a large proportion of the landscape burns annually. Previous research has suggested that shifts in land use and agricultural practices have modified the fire regime of Cote d’Ivoire over the past 30 years. Specifically, increasing pastoralism in north-central Cote d’Ivoire has been shown to coincide with a shift in fire seasonality toward fires earlier in the dry season. We investigated decadal trends in monthly fire occurrence across Cote d’Ivoire to determine whether similar processes of shifting fire seasonality are at play at the national scale. We assessed fire occurrence using remotely sensed Landsat imagery covering the entire extent of Cote d’Ivoire across a 30-year period from 1984 to 2014. The fine resolution of Landsat imagery makes possible the detection of small fires that commonly occur in heavily managed West African savannas. We investigated trends in the timing of both active fires and burned areas. Active fires were detected using shortwave infrared emissions of fire, and burned areas were identified based on spectral and temporal patterns distinctive to burn scars. The timing of fire occurrence influences fire intensity, and shifting fire seasonality has implications for land cover and terrestrial carbon budgets. Our findings point to temporal-spatial shifts in fire regimes over the past three decades and advance understanding of the contribution of West Africa’s savannas to global greenhouse gas emissions.