Greenhouse gas emissions from savanna fires: What analysis of cultural burning regimes in a working West African landscape tell us

Keywords: Savanna fires, greenhouse gases, emission factors, combustion efficiency, Africa
Session Type: Virtual Paper Abstract
Day: Tuesday
Session Start / End Time: 3/1/2022 09:40 AM (Eastern Time (US & Canada)) - 3/1/2022 11:00 AM (Eastern Time (US & Canada))
Room: Virtual 20

Abstract

Savanna fires contribute significantly to greenhouse gas (GHG) emissions. While it is recognized that these fires play a critical role in global cycles, there are too few accurate estimates of emissions from West Africa, the world’s most active fire region. Most estimates of GHG emissions contain high levels of uncertainty as they are based on generalizations of diverse landscapes that are burned by complex fire regimes, which are a function of cultural burning practices. To improve estimates we used an approach grounded in the burning practices of people who set fires to working landscapes. We collected and analyzed gas samples from over 100 experimental fires using a gas analyzer in real time to sample smoke from just above the flaming fire front. We conducted experiments for early dry season (EDS), mid-dry seasons (MDS) and late dry-season (LDS) to determine how seasonality affects different gas emissions. We also collected data for savanna type, grass type, biomass composition and amount consumed; scorch height, speed of fire front, fire type and ambient air conditions for two sites in southern Mali. We statistically analyzed data to determine the key factors effecting fire intensity, patchiness, combustion efficiency, modified combustion efficiency (MCE) and emission factors (EFs) for three key gases—CO, CO2 and CH4. Results find that fire type (head or back) strongly influences fire intensity, MCE, and EFs and that MDS fires have distinct characteristics from other fires. The implications of cultural burning practices on key factors and the potential for GHG mitigation are discussed.