Fire behaviour and severity in a maritime pine stand under differing fuel conditions

An experimental fire was conducted in the summer in a 28-year old maritime pine ( Pinus pinaster) plantation in northeastern Portugal. Fuel conditions within the stand were age-dependent and comprised four situations: treated with prescribed fire at differing times, respectively 2, 3, and 13 years before the study, and undisturbed, where fuel accumulation time equalled stand age. The rate of fire spread did not respond to factors other than wind speed, in spite of the fuel-complex diversity. A high-intensity fire involving partially or totally the tree canopy and killing all trees was experienced in the older treatment area and in the untreated part of the stand, but the benefits of fuel management were still detectable in the former. Surface fire intensity, crown fire potential and fire severity ( including tree mortality) were drastically reduced where prescribed fire had been carried recently. Fuel and fire management implications are discussed.