How forest fires kill trees: A review of the fundamental biophysical processes

Postfire tree mortality is typically characterized using regression approaches that do not consider the causal processes linking fire behavior and tree mortality. Recently, a growing number of studies has used biophysical process approaches that attempt to define and independently validate these causal processes. Nevertheless, some foresters and ecologists are unfamiliar with the approach and it remains a minority in fire ecology research. The purpose of this review is to describe in straightforward terms the fundamental biophysical processes that link fire behavior to tree mortality. The review begins with a brief introduction to heat transfer theory before moving on to combustion processes and forest fire behavior. A discussion follows on how fire behavior is linked to injuries in the tree roots, bole and crown, and finally a biophysical process framework for linking root, bole and crown injuries to tree mortality is outlined. It is hoped that this overview will promote future process approaches and help to produce more predictive and general models of postfire tree mortality.