Modeling fire regimes for fire management in protected areas (Canada)

In protected areas where ecologically beneficial fire impacts are promoted through efforts to accommodate or support fire processes on the landscape, fire and park managers who are challenged to manage active fires in limited areas must assess fire risks, predict fire effects, and evaluate the long-term ecological consequences of fire management alternatives. In this thesis, three fire regime models designed to support fire management planning in protected areas are developed and presented. First, the statistics of extreme values was applied to historical fire and weather data to characterize dry-spell and fire extremes in the province of Ontario. The results of this landscape-level analysis of fire processes indicated that regional differences in the magnitude of extreme fire events is related to extreme dry-spell events, ecological classification, and level of fire protection. Second, postfire field study data were used to develop a logistic regression model to predict white pine (Pinus strobus L.) mortality following an intense surface fire. Results of this stand-level analysis of fire effects indicated that tree size and fire intensity are key determinants of postfire mortality, corroborating existing evidence that mature white pine are resistant to intense surface fire. Third, a simple model of white pine stand dynamics was developed to evaluate prescribed fire scheduling strategies for achieving ecological objectives using both simulation modeling and goal programming methods. Results of this stand-level analysis of long-term fire processes illustrated the usefulness of simulation models for identifying a preferred fire return interval within the range of natural intervals, given specific management objectives. Simulation results supported the intermediate disturbance hypothesis and suggest that in forest stands subject to regular, non-catastrophic disturbance, frequency of disturbance may be a key mitigating factor in the diversity-stability relationship. Goal programming results demonstrated that optimal prescribed fire schedules based on habitat and visual quality goals can produce ecological outcomes consistent with outcomes associated with schedules based on a preferred natural fire return interval. This multi-objective approach to prescribed fire scheduling in an uneven-aged stand is a novel formulation of the optimal fire management problem.