Stand specific litter moisture content calibrations for the Canadian Fine Fuel Moisture Code

The relationship between the diurnally adjusted Fine Fuel Moisture Code (FFMC) of the Canadian Forest Fire Danger Rating System and actual litter moisture was studied for a range of stand types and stand closures. Data were collected as part of an extensive program of fuel moisture and fuel ignitability testing carried out by the Canadian Forest Service across Canada from 1940 to 1961. Models for relating calculated FFMC value to actual litter moisture were developed for: a number of forest types (pine, spruce, mixedwood, deciduous, and fir); stand closure (sparse, moderate, dense), and for season (spring, summer or fall). Moisture content of the organic layer was also found to have a significant influence on the relationship between FFMC and observed litter moisture in these stands, and a model for adjusting the FFMC for organic layer moisture is also developed. Potential applications of these new models are discussed.