Abstract

RODRIGUEZ-TREJO, Dante A. et al. Comparative analysis of prescribed burns applied to tropical oak woodlands. Agrociencia [online]. 2018, vol.52, n.6, pp.783-801. ISSN 2521-9766.

Forest fires and agricultural burns contribute to global climate change, and the latter is a tool that reduces CO2 emissions. The objective of this study was to evaluate the consumption of surface fuels, fire behavior, and emissions in prescribed burns. The hypothesis was that fires affect more fuels and produce more emissions than prescribed burns. Prescribed burns were applied in six randomly-established experimental plots in a tropical oak woodland in Chiapas, Mexico: three heading and three backing fires. Measurements and estimates included: initial and residual fuel loads, consumption factors, and CO2 emissions. Wind speed and direction, temperature and relative humidity, fire spread rate, and flame length were recorded during the burns. In a forest fire, the flame length and the residual fuel load were determined. The t- and the Wilcoxon (under lack of normality) tests were applied. In the heading and backing fires, there were significant differences in the fire spread rate (3.63 and 0.59 m min-1), but there were none in the flame length (0.91 and 0.72 m). The flame length of fires reached 1.94 m, but burns had different results. The total fuel loads in backing and heading fires were 28.393 and 35.512 t ha-1, without differences between them; the consumption factors for backing and headingfires and forest fire reached 92.7, 87.5, and 97.2 %, without showing any difference; however, the forest fire affected aerial fuels. The CO2 emissions reached 44.53, 51.14, and 53.78 t CO2 ha-1. The prescribed burns help to reduce emissions, because their intensity and severity are lower than those of forest fires. Consequently, since burns affect a smaller surface, they help to prevent fires and to reduce emissions.

Keywords : CO₂; climate change; greenhouse effect; fire; fire management.