PROBABILITY OF MORTALITY IN CASUARINA TWO YEARS AFTER THE FIRE AT THE PIEDMONT OF THE TLALOC VOLCANO, STATE OF MEXICO, 2017

Abstract

In 2017, at the foot of the Tlaloc volcano, occurred the largest forest fire in the State of Mexico (2500 ha), with surface and crown (canopy) phases, on plantations of various species and various types of vegetation. Studies on the effects of fires on trees serve to define mortality and whether or not restoration will be required in an affected area. The hypothesis was: the greater the intensity and severity of the fire and the smaller the size of the trees, the greater the probability of mortality. The objective of the study was to establish the fire severity and dasometric variables that influence the probability of both mortality and resprouting in Casuarina equisetifolia L. plantations affected by fire. The study was conducted at the Experimental Forestry Station “Las Cruces” (Universidad Autónoma Chapingo, State of Mexico). In 2019, 442 trees (15 sites of 100 m2) were sampled in 50 ha of plantations affected by the fire. Records were made on whether the trees were alive or dead, normal diameter, bark thickness, height, height at the base of the original crown, height of the fire scar on the trunk, height of crown scorch and presence of resprouting. The statistical analysis consisted of logistic regressions, using the Proc Logistic procedure of the SAS program. The average tree mortality was 63 %. The variable that was directly related (p ≤ 0.05) to the probability of mortality was the height of the scar above the trunk. The dasometric variables inversely related (p ≤ 0.05) with the probability of mortality were: height, normal diameter and bark thickness. For resprouting probability, there was an inverse relationship (p ≤ 0.05) with normal diameter, bark thickness and height of scar on the trunk. It is concluded that casuarina is a fire sensitive species.