A comparison of fire danger rating systems for use in forests

Fire danger indices are an important tool for fire and land managers. This study examines two fire danger indices developed for use in Australian forests, the Forest Fire Danger Index and the Forest Fire Behaviour Tables, and a third, the Fire Weather Index, which was developed for use in Canadian pine forests but is finding use in other countries. The indices are described and their structures examined by comparing the response of each index to wind, fuel moisture, and fuel availability. The application of the indices is examined by comparing their predictions across a range of wind, fuel moisture, and fuel availability conditions, and in a case study using weather station data. The three systems are found to have similar structures but to provide widely varying assessments of fire danger for a given set of inputs. In the case study, differences between how weather variables are incorporated by the indices cancelled out some of the differences in structure and the results were in closer agreement, particularly for the two systems developed for eucalypt forest.