Justin Podur

Spatial patterns of lightning-caused forest fires in Ontario, 1976-1998

The spatial pattern of forest fire locations is of interest for fire occurrence prediction and for understanding the role of fire in landscape processes. A spatial statistical analysis of lightning-caused fires in the province of Ontario, between 1976 and 1998, was carried out to investigate the spatial pattern of fires, the way they depart from randomness, and the scales at which spatial correlation occurs. Fire locations were found to be spatially clustered. Kernel estimation of the spatial pattern of lightning strikes on days when the dryness of the forest floor exceeded a designated threshold yielded clusters in the same areas as the lightning fire clusters.

The influence of weather and fuel type on the fuel composition of the area burned by forest fires in Ontario, 1996-2006.

Forest fires are influenced by weather, fuels, and topography, but the relative influence of these factors may vary in different forest types. Compositional analysis can be used to assess the relative importance of fuels and weather in the boreal forest. Do forest or wild land fires burn more flammable fuels preferentially or, because most large fires burn in extreme weather conditions, do fires burn fuels in the proportions they are available despite differences in flammability? In the Canadian boreal forest, aspen (Populus tremuloides) has been found to burn in less than the proportion in which it is available. We used the province of Ontarios Provincial Fuels Database and fire records provided by the Ontario Ministry of Natural Resources to compare the fuel composition of area burned by 594 large (>40 ha) fires that occurred in Ontarios boreal forest region, a study area some 430,000 km2 in size, between 1996 and 2006 with the fuel composition of the neighborhoods around the fires. We found that, over the range of fire weather conditions in which large fires burned and in a study area with 8% aspen, fires burn fuels in the proportions that they are available, results which are consistent with the dominance of weather in controlling large fires.

A simulation model of the growth and suppression of large forest fires in Ontario

Most of the area burned by forest fires in Canada is due to the few fires that escape initial attack and become large. We developed a discrete event simulation model of the growth and suppression of large fires in the province of Ontario. Based on fire, weather and suppression data from the Ontario Ministry of Natural Resources, our model includes a logistic regression component to predict the probability that a fire will escape initial attack and burn more than 100 ha, a component that simulates the growth of large fires based on weather and forest vegetation, and a component that simulates fire suppression by firefighters and aircraft. We used our model to predict area burned under mild and severe weather with varying levels of fire suppression resources. We found that, although severe weather limits fire suppression effectiveness, suppression has a significant effect on area burned even during severe fire seasons.

Defining fire spread event days for fire-growth modelling

Forest fire managers have long understood that most of a fire’s growth typically occurs on a small number of days when burning conditions are conducive for spread. Fires either grow very slowly at low intensity or burn considerable area in a ‘run’. A simple classification of days into ‘spread events’ and ‘non-spread events’ can greatly improve estimates of area burned. Studies with fire-growth models suggest that the Canadian Forest Fire Behaviour Prediction System (FBP System) seems to predict growth well during high-intensity ‘spread events’ but tends to overpredict rate of spread for non-spread events. In this study, we provide an objective weather-based definition of ‘spread events’, making it possible to assess the probability of having a spread event on any particular day. We demonstrate the benefit of incorporating this ‘spread event’ day concept into a fire-growth model based on the Canadian FBP System.

SPATIAL POINT PATTERN ANALYSIS OF LIGHTNING-CAUSED FOREST FIRES IN THE BOREAL FOREST REGION OF ONTARIO

The spatial pattern of forest fires is of interest for fire occurrence prediction and for understanding the role of fire in the landscape. Fire is not a spatially random process— fire is more likely to occur at some locations than others. We have investigated the spatial pattern of fires, the way they depart from randomness, and the scales at which spatial correlation occurs. We report on a spatial statistical analysis of lightning-caused fires in the province of Ontario, between 1976–1994.