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Abstract
Fuels management in eucalyptus plantations is essential to minimise the impact of wildfire. Prescribed burning has the potential to reduce the fuel hazard in plantations, but is not routinely conducted due to concerns relating to tree damage. Through a series of experimental burns, the issues of tree damage are addressed and minimum tree sizes are recommended that are capable of withstanding the effects of low to moderate intensity fires. Data was collected between 2005 and 2007 over six sites, two species, and three age classes. Tree response results came from multiple measurements of over 1700 individual trees. The fuel characteristics commonly found in sub-tropical eucalypt plantations from age four to eleven are described and quantified. These fuel characteristics are related to fire behaviour and new fire behaviour models, specific to young eucalypt plantations, are presented. The fuel characteristics that most influence fire behaviour in young eucalypt plantations are fuel load, fuel height, and fuel moisture content. These characteristics can be used to predict the rate of spread of a plantation fire under benign wind conditions. A novel technique for assessing the extent of stem damage in eucalypts is developed and described. This technique enables immediate assessment of stem damage following fire; previous assessment techniques recommend waiting a considerable period of time (up to 2 years) until dead bark dropped off and fire scars were evident. This new assessment technique is likely to be suitable for post-fire assessment of any eucalypt species and will provide forest managers with the capability of deciding whether to leave a stand to grow-on or commence recovery operations. Minimum stem sizes recommended to ensure no long-term damage are between 5 8 cm DBH (diameter at breast height, i.e. 1.3m above ground level) for Eucalyptus dunnii (Dunn s white gum) and 5 13 cm DBH for Corymbia spp. (spotted gum) depending on the quantity of fuel around the stem. Stem sizes vary between species because of the variation in bark thickness between species. This thesis provides all the necessary information to conduct prescribed burning operations in young eucalypt plantations.