Managing multiple species or communities? Considering variation in plant species abundances in response to fire interval, frequency and time since fire in a heathy Eucalyptus woodland

With the prospect of altered levels of fire in mediterranean-type environments due to changing climatic conditions, managers are faced with the need to regulate fire with an incomplete knowledge of the ecological outcomes of their actions. Burning intervals for natural vegetation are often determined by using methods which provide an indication of ‘appropriate’ intervals based on the tolerances of key fire response species. The research presented here is an investigation into variation in species abundance in response to fire frequency, interval and time since fire. An ordination of species composition constrained by the corresponding fire history matrix revealed limited response at a community level. However, when species were considered individually using quantitative models, over half of the species responded significantly to at least one of the assessed components of fire regime. Species richness exhibited little variation; however there was change in species diversity (Shannon H) in response to time since fire. Quantitative models showed a range of species responses to fire, indicating that any given regime will favour some species at the cost of others. This study demonstrated that while current techniques provide guidance on tolerable fire intervals, such an approach is not necessarily ideal for all species. The determination of ecologically meaningful fire regimes may be better served when the changing abundances of species of interest are also taken into account.

► Functional trait approaches to fire ecology do not recognise variation in abundance. ► We assessed plant responses to fire interval, frequency and time since fire. ► The majority of plants exhibited changes in abundance due to fire. ► Consideration of species specific variation may be necessary to achieve management goals.