Near zero mortality in juvenile Pinus hartwegii Lindl. after a prescribed burn and comparison with mortality after a wildfire

Abstract

Abstract: Fire is considered a relevant ecological factor, however, human alterations of fire regime facilitate more destructive wildfires. The aims of this work were to model probability of tree mortality and to identify the factors associated with leader shoot growth in a prescribed burn area and in a nearby wildfire area in a juvenile Pinus hartwegii Lindl. stand in central Mexico. A prescribed burn was carried out in 10-ha stand in March 2012, and compared with a close area affected by a wildfire occurred one week later, as well as with a nearby unburned area taken as control. A logistic model was used to estimate the probability of mortality, and a linear regression model was employed to investigate factors related to leader shoot growth. No tree mortality was recorded in the unburned control. In contrast, mortality was 6% in the prescribed burn and 66.9% in the wildfire area. The probability of mortality was influenced by stem char height (positively, p<0.0001), tree height (negatively, p=0.0443), and diameter at breast height (negatively, p<0.0001). The variables that had more influence on leader shoot growth were stem char height (negatively, p<0.0001) and tree height (positively, p<0.0001). This work supports evidence of the feasibility of using low intensity prescribed burns in this ecosystem with minimum effects on young tree mortality.