ESTIMATING THE HISTORIC PROBABILITY OF STAND-REPLACEMENT FIRE USING THE AGE-CLASS DISTRIBUTION OF UNDISTURBED FOREST

A simple probabilistic model for the destruction of forest stands.by f ire is used to determine a likelihood function for the problem of esti mating the per annum probability of stand-replacement fire using data in the form of areas in various age classes of undisturbed old-growth forest. This enables the estimation of either an age-independent fire probability or of the parameters of a parametrically defined age-depen dent probability. The model includes contagion effects (the probabilit y of a stand burning being increased by other stands burning). Maximum likelihood is used to obtain estimates of the age-independent per ann um probability of stand-replacement fire (or the parameters of an age- dependent model), along with a contagion parameter. Confidence interva ls for the fire probability are also obtained.