Forest fire danger rating research in Canada was initiated by the federal government in 1925. Five different fire danger rating systems have been developed since that time, each with increasing universal applicability across Canada. The approach has been to build on previous danger rating systems in an evolutionary fashion and to use field experiments and empirical analysis extensively. The current system, the Canadian Forest Fire Danger Rating System (CFFDRS), has been under development by Forestry Canada since 1968. The first major subsystem of the CFFDRS, the Canadian Forest Fire Weather Index (FWI) System, provides numerical ratings of relative fire potential based solely on weather observations, and has been in use throughout Canada since 1970. The second major subsystem, the Canadian Forest Fire Behavior Prediction (FBP) System, accounts for variability in fire behavior among fuel types (predicting rate of spread, fuel consumption, and frontal fire intensity), was issued in interim form in 1984 with final production scheduled for 1990. A third major CFFDRS subsystem, the Canadian Forest Fire Occurrence Prediction (FOP) System, is currently being formulated. This paper briefly outlines the history and philosophy of fire danger rating research in Canada discussing in detail the structure of the current CFFDRS and its application and use by fire management agencies throughout Canada. Key words: fire danger, fire behavior, fire occurrence prediction, fuel moisture, fire danger rating system, fire management.

Forest fire danger rating research in Canada was initiated by the federal government in 1925. Five different fire danger rating systems have been developed since that time, each with increasing universal applicability across Canada. The approach has been to build on previous danger rating systems in an evolutionary fashion and to use field experiments and empirical analysis extensively. The current system, the Canadian Forest Fire Danger Rating System (CFFDRS), has been under development by Forestry Canada since 1968. The first major subsystem of the CFFDRS, the Canadian Forest Fire Weather Index (FWI) System, provides numerical ratings of relative fire potential based solely on weather observations, and has been in use throughout Canada since 1970. The second major subsystem, the Canadian Forest Fire Behavior Prediction (FBP) System, accounts for variability in fire behavior among fuel types (predicting rate of spread, fuel consumption, and frontal fire intensity), was issued in interim form in 1984 with final production scheduled for 1990. A third major CFFDRS subsystem, the Canadian Forest Fire Occurrence Prediction (FOP) System, is currectly being formulated. This paper briefly outline the history and philosophy of fire danger rating research in Canada discussing in detail the structure of the current CFFDRS and its application and use by fire management agencies throughout Canada. Key words: fire danger, fire behavior, fire occurrence prediction, fuel moisture, fire danger rating system, fire management.

Climate change may profoundly influence Ontario's forest ecosystems and their management. Elevated atmospheric C 0 2 concentrations, increased temperature and altered precipitation regimes will affect forest vegetation through their influence on physiological (e.g., photosynthesis, respiration) and ecological processes (e.g., net primary production, decomposition), and may result in dramatic northward shifts in the natural range of forest types and species. More importantly, climate change is expected to increase the frequency of natural disturbances. Silvicultural intervention will increasingly be relied on to maintain forest health, manage declining stands, regenerate disturbed areas and cutovers with desired species and genotypes, maintain genetic diversity, and assist in species migration. Given the increasingly important role of Ontario's forests in national and provincial efforts to meet greenhouse gas emission reduction targets of the Kyoto Protocol, afforestation, conservation of existing forests, and increased forest management activities to accelerate the storage of carbon in Ontario's forests will be key aspects of forestry at the start of the third millennium.Key words: adaptation, afforestation, bioenergy, carbon dioxide, climate change, disturbance, intensive forest management, migration, mitigation, sequestration, succession Le changement climatique pourrait modifier en profondeur les Ccosyst5mes forestiers de I'Ontario et la f a~o n de les amtnager. Les concentrations ClevCes de C02 atmosphCrique, la temptrature plus ClevCe et les regimes de precipitations modifiks affecteront la vCg& tation forestibre suite B leurs influences sur les processus physiologiques (p. ex. la photosynthbe, la respiration) et 6cologiques (p. ex. la production nette primaire, la dCcomposition), et pourraient entrainer des diplacements dramatiques vers le nord de la distribution naturelle des types de for& et des espbces. De f a~o n encore plus importante, on s'attend 2 ce que le changement climatique accroisse la frCquence des perturbations naturelles. Les interventions sylvicoles dCpendront de plus en plus du maintien de la santC des for&, de I'amCnagement des peuplements en dkclin, de la rkgtntration des superficies perturbhs et toupees au moyen d'espkes et de gCne types dCsirts, du maintien de la diversitt gCnCtique, et de l'aide clans la migration des espbces. fitant donne le r6le de plus en plus importants que jouent les for& de I'Ontario au niveau des efforts nationaux et provinciaux de correspondance aux objectifs de rtduction des gaz B effets de serre selon le protocole de Kyoto, le boisement, la conservation des forets actuelles, et l'accroissement des activitCs d'amknagement forestier pour accCl6rer la skquestration dur carbone dans les for& ontariennes seront des aspects dominants en foresterie au dtbut de troisibme millCnaire.

A structured expert-judgement elicitation technique was used to develop probability distributions for fireline production rates for Ontario's three- and four-person initial-attack crews for seven common fuel types and two distinct levels of fire intensity (i.e., low, 500 kW/m; moderate, 1500 kW/m). A total of 141 crew leaders provided 900 estimates of the minimum, maximum, and most likely (mode) time to construct 610 m (2000 ft) of fireline. This information was used to estimate parameters for beta probability distributions for each individual and scenario. Analysis of variance (ANOVA) of the beta-distribution parameters (α and β) and the three time estimates indicated that fuel type, intensity, crew size, and crew-leader experience all have a statistically significant (p < 0.05) influence on estimated crew productivity. The 28 scenario-specific and 7 aggregated distributions and expected values can be used in many operational fire-management activities (e.g., presuppression planning, initial-attack dispatching, initial-fire assessments) and incorporated into initial-attack containment models. These results also provide baseline data on crew productivity that can be used in larger strategic analyses to gauge the benefits of new fire-suppression equipment and techniques for the entire fire-management program.

To determine the effect of fire front width on surface fire spread rates, a series of simultaneously ignited experimental fires was carried out in a pine plantation. Fires were ignited in plots with widths ranging from 0.5 m to 10 m and were burned in low wind conditions. Flame lengths were small in all fires, ranging from 20 cm to 60 cm. Since pre-heating of the forest litter from flame radiation is assumed to be an important mechanism in the spread of low intensity, low wind surface fires, it then follows that the width of a flaming front should effect on the heating of the fuel to ignition temperatures. Total flame radiation was also measured at a point 50 cm ahead of the advancing flame front for a number of the fires. Experimental results indicate that a flame radiation measured ahead of the fire stays fairly constant once the flame width is between 2 and 5 m. Theoretical flame radiation calculations confirm this trend. Rates of spread between the 5 and 10 metre width fires also appear to be similar; this indicates that, for the type of fires studied, once flame width is greater than about 2 m, radiation from any extra width of fire front has little effect on spread rate.