A Basic Approach to Fire Injury of Tree Stems

F IRE HAS COME to be widely llsed as a tool in wildland management, particularly in the South. Its usefulness in fire hazard reduction, removal of undesirable trees, and changing of cover types has been demonstrated. We are continually trying to improve fire lISC, however, by learning more of the specific effects of fire on different species of plants. lvlosr fire effects studies are conducted by observing conditions following one or morc fires . In the study described here, the approach has been to measure the separate factors involved in fire injury, and then to predict rhe effect of a given nre on tree stems. Some phases of the study arc complete, whereas much more informacion is needed in others. The purpose of this paper will be not to describe in detail any part of the study, but to outline the approach raken. The problem has been considered in three parts. First, there is the heat pulse to which the stem is sub jected. This heat pulse is the high temperatures produced by the fire. Second are the stem characteristics. This part consists of the thermal properties of bark and wood, and also bark thickness, bark fissu ring, and stem diameter. Third arc lethal temperatures. Although these have nOt yet been studied at the laboratory, consideration has been given to use and manipulation of lethal data take n fr0111 the literature.