Fire season and intensity: implications for plant conservation

Abstract

Fire is pervasive in Australian ecosystems but surprisingly we know little of its conservation implications when it occurs in different seasons and at different fire intensities. From tropical north to the temperate south most vegetation in Australia burns when it is dry and there is a source of ignition. Even the rainforests of eastern Australia are known to burn after prolonged droughts such as occurred in 2001-2002 (Marrinan et al. 2005). Much of the popular media focuses upon the tragic events of these fires, and when reporting on biodiversity consequences, again the focus is on the severity of the event rather than the fire regime. Most conservation managers realise that it is not the fire event per se but the cumulative impact of fires over time that drives changes in biodiversity. Such a history of fire is termed the fire regime and is often simplified into three key interacting components; frequency, intensity and season of fire. It is well known that short intervals between fires can drive plant populations to local extinction, especially when species are slow to mature and their seed banks are not persistent. Less well known are the consequences of season and intensity of fire but recent experimental studies have revealed the risks to plant biodiversity from inappropriate regimes.