Effect of fuel composition on combustion efficiency and emission factors for African savanna ecosystems


  • D. E. Ward,

  • W. M. Hao,

  • R. A. Susott,

  • R. E. Babbitt,

  • R. W. Shea,

  • J. B. Kauffman,

  • C. O. Justice


Savanna burning in Africa occurs over a wide range of environmental, vegetation, and land use conditions. The emission factors for trace emissions from these fires can vary by a factor of 6 to 8, depending on whether the fires burn in miombo woodlands or in ecosystems where grass vegetation dominates. Ground-based measurements of smoke emissions and aboveground biomass were made for fires in grassland and woodland savanna ecosystems in South Africa and Zambia. A high combustion efficiency ( inline image) was measured for the pure grassland; i.e., a high proportion of carbon was released as CO2. The inline image was lower for woodland savanna ecosystems with variable amounts of grass and with a more compact layer of leaf material and litter lying near the ground. The inline image was found to be dependent on the ratio of grass to the sum of grass and litter. Models developed for estimating emissions were integrated in a nomogram for estimating total emissions of CO2, CO, CH4, nonmethane hydrocarbons, and particles of less than 2.5 μm diameter per unit area.