Fire ecology of the spinifex hummock grasslands of Central Australia

Abstract

Australia's spinifex hummock grasslands are arid ecosystems that experience intermittent but widespread fires. These fires occur in response to above-average rains, which cause biomass levels to increase and allow fuel contiguity to occur. Previously, there was very little scientific understanding of the ecological effects of these wildfires on spinifex grasslands, although anecdotal evidence suggested that a recent fire 'event' (2000-02) had been catastrophic to both plant and animal populations. This thesis was concerned firstly with quantifying the contemporary fire regime of the spinifex grasslands of the Haasts Bluff Aboriginal Reserve, west of Alice Springs, and secondly, with improving understanding of how fire regimes affect vegetation dynamics within these grasslands. ... The results of the field surveys were explored more fully in field experiments in which four species of Acacia were burned under differing fire intervals, seasons and 'severities'. These experiments demonstrated that the selected Acacia species could resprout repeatedly after short fire intervals, though high levels of mortality were observed for certain species under high severity and/or summer burns. Additionally, most woody species failed to be detected in the seed bank. This result was largely explained by seed removal and decay experiments, which revealed that seeds of these species would be removed by seed predators almost immediately after seed fall.