Fuel dynamics and vegetation recovery after fire in a semiarid Australian shrubland
School of Science / Centre for Ecosystem Management
Understanding fuel dynamics in fire-prone ecosystems is important because fuels play a central role in shaping fire hazard and behaviour. There is ongoing debate over whether fire hazard continually increases with time since fire in shrublands of Mediterranean-Type climates, and studies of the temporal changes in fuel loads can contribute to this discussion. We used a chronosequence of fire ages to investigate fuel dynamics and recovery of vegetation structure in the Acacia-dominated shrublands of interior south-west Western Australia. We collected and measured fuels from vegetation with fire ages ranging from 6 to 80+ years and then fitted linear, negative exponential, quadratic and logarithmic models to explore temporal patterns of fuel accumulation. Components of fine (50 years). Although there is some evidence of shrub senescence in very long-unburnt vegetation (>60 years), no corresponding decline in fuel levels was detected, suggesting lag effects or inter-fire recruitment to maintain vegetation structure and fuel levels. Fuel structure and quantity varied considerably across the landscape, even within areas of the same landform and time since fire. We found that some of this variation was attributable to soil depth but suggest that other environmental factors may also cause variation in vegetation and fuel characteristics.