Assessment of existing fine fuel moisture models applied to Eucalyptus litter

Summary

The diurnal trends in dead leaf, bark and twig moisture content on the floor of a Eucalyptus forest in south-eastern Australia were examined over a four day period. Substantial differences were found in moisture content among the three fuel types. At night the twigs remained the driest, while the leaves, through condensation of dew and distillation of moisture from the soil, were the wettest. During the daytime the leaves and bark reached lower fuel moisture minima than the twigs. The adequacy of several fine fuel moisture models was assessed. The locally developed Grassland Fire Danger Meter and Forest Fire Danger Meter together with the Fire Behaviour Officer's model were the best predictors of diurnal fuel moisture content. The usefulness of the timelag concept in Eucalyptus fuels is discussed and the results of the study suggest that modifications should be made to the Fine Fuel Moisture Code and the BEHAVE model for application to these fuels. The need to incorporate a parameterisation of nocturnal condensation into existing models is indicated.