Date of Award

1996

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Science, Technology and Engineering

First Supervisor

Dr John Koch

Second Supervisor

Eddie Van Etten

Abstract

This investigation assessed the fuel characteristics of Alcoa of Australia's rehabilitated bauxite mines in the south-west of Western Australia. The study determined the fuel loads, their composition and structure. The characteristics of fuel were determined, their relationship with time ascertained, and the similarity of these characteristics to the jarrah forest ecosystems that they have replaced was discussed. Pits aged from four to twenty years since rehabilitation were assessed. Predictive models were developed to allow the rapid assessment of fuel. The fuel characteristics in two controlled bum areas were also assessed to how much fuel would burn in a fire and what factors were effecting this consumption. Fuel quantities increased with age since rehabilitation from 7.19t/ha in a 5 year-old pit to 68.23t/ha in a 17 year-old pit. This is up 6 times higher than the maximum levels suggested for the surrounding jarrah forest. The distribution of fuels was very heterogeneous in nearly all sites. It was much more variable than in the surrounding jarrah forest. For example, fuel loads sampled in a 15 year old site, ranged from approximately 20t/ha to 120t/ha. This uneven fuel distribution will influence fire behaviour and intensity during controlled bums. Measurement of fuel consumption showed that a spring burn of moderate to high intensity consumed more fuel than an autumn burn of lower intensity. The higher moisture content of the autumn burn area contributed to the lower consumption of fuel as moisture inhibits combustion. More than 88% of standing fuel was consumed in the bums. Research data suggests that fire is carried in this standing fuel component. This differs from the jarrah forest where fire is carried in the litter layer. This implies that measurements of moisture content in soils and litter, which are used in other models to predict fire behaviour, would be of limited use in the rehabilitation areas under 15 years of age which have a significant proportion of standing fuel. Although many other factors need to be considered in relation to the controlled burning of rehabilitated areas, the findings of this study have important implications. The fuel characteristics in 4 to 20 year-old rehabilitated areas are different to the jarrah forest ecosystem that they have replaced. At this stage the areas need to be treated differently in the development of a fire management programme.

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