Fire effects on the trees of a tropical pine forest and a tropical dry forest at Villaflores, Chiapas, Mexico

Abstract

It is expected an increase of forest fires world-wide because of global warming. So is important the study of fire ecology and fire effects in different ecosystems. In Villaflores, Chiapas, Mexico, are conducted efforts towards the integral fire management. There was studied a Pinus oocarpa Schiede forest, as well as a tropical dry forest, affected by forest fires 6 and 18 months before, respectively. The objectives were: To model the probability of mortality and probability of resprouting in the former, and to study mortality, composition and fire-traits in the later. In both forests were recorded dasometric and fire severity variables, and calculated importance values. For the pine forest were obtained logistic models to estimate probabilities of mortality and basal resprouting. The obtained models confirm fire adaptations and tree-traits that facilitate tree survival. High values in tree height, basal diameter, diameter at breast height, height to the base of crown and bark thickness, reduce probability of mortality. But high levels of fire trunk scar height, increase it. Despite this species is fire-adapted with thick bark, epicormic resprouts that restore the crown, basal resprouting and regeneration; the forest fire was severe, pine mortality reached 48,8%, and the mean trunk scar height was 1,5 m ± 1,3 m. In the tropical dry forest the fire was not severe, with a mortality of 5%, and were recorded 37 tree species, 28 of them with several fire-traits, such as: thick bark, physical dormancy in seeds or pyrene in the fruit, regeneration and resprouting. The prevalence of fire-adapted species, shows the possibility that they are the result of historic fires that eliminated sensitive species and that in this altered tropical dry forest there are more fire-adapted species than thought, so is fire-influenced.