Carbon emissions and vertical pattern of canopy fuel consumption in three Pinus pinaster Ait. active crown fires in Galicia (NW Spain)

Accurate estimation of the canopy fuel load that is consumed during crown fires is critical for improving our knowledge of crown fire behaviour and for quantifying emissions of carbon and other gases during this type of fire. However, there is a lack of information about the actual fuel loads consumed during combustion of the forest stand canopy. Three active crown fires in Pinus pinaster stands were selected for quantification of pre- and post-fire vertical fuel load distribution in the canopy, and for the first time an assessment was made of the fuel consumed by size classes and categories (needles, twigs < 6 mm and fine branches 6-25 mm). Relative canopy load consumption was between 56% and 66%. The results revealed that all foliage and most of the dead twigs and fine branches were consumed by fire, and that pre-fire basal area was a good predictor of the total fuel load consumed. Carbon emissions from the canopy during active crown fires was between 3.0 MgC ha−1 and 5.0 MgC ha−1. These results may be useful for both crown fire physical modelling and for assessing regional sources and sinks of CO2. Moreover the information will help in the development of fuel treatments to reduce active crown fire hazard.