Fire in Gimlet Woodlands

Fire regimes and effects of fire in gimlet (Eucalyptus salubris) woodlands

Disturbances are important ecosystem processes affecting patterns of species diversity (including species richness, diversity and evenness) and community composition. Determining appropriate disturbance regimes for particular ecosystems is thus an important issue for natural resource management. There have been few studies of the response of plant species composition and diversity to fire in 'fire-sensitive' Mediterranean-climate woodlands, where the dominant overstorey trees are typically killed by fire, resulting in dense post-fire recruitment. The Great Western Woodlands (GWW) region of south-western Australia supports the world's largest remaining area of Mediterranean-climate woodland, which in mosaic with mallee, shrublands and salt lakes cover an area of 160 000 km2. Eucalyptus woodlands in this region are typically fire-sensitive, and fire return intervals recorded over recent decades have been much shorter than the long-term average. This has led to considerable conservation concern regarding the loss of mature woodlands, and has highlighted a need to better understand how plant species composition and diversity changes with time since fire. We established a series of plots in gimlet woodlands within the Great Western Woodlands TERN Supersite at a range of times since fire (72 50 x 50 m plots). To estimate plot ages for this study we used satellite imagery, growth ring counts and relationships between growth ring counts and plant size.