Thursday 11th April 2019
Doors open 5:30pm for 6pm start
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Postfire seedling recruitment is vital for the persistence of many plant species in fire-prone ecosystems. The season of fire is known to have an impact on recruitment success in Mediterranean-climate ecosystems with research showing that recruitment of serotinous species (e.g. banksias) is best after dry-season fires; however, there is no information on recruitment of soil-stored species (e.g. acacias). Altered fire seasonality due to changing climate conditions and human activities is, therefore, a cause for concern for these species. In the research presented here, I quantified the impact of planting seeds at monthly intervals during autumn-spring (to simulate the timing of fire throughout the year) on seedling emergence and survival as well as seed survival over summer for those failing to germinate in the first year. For the Banksia woodland species studied, recruitment of serotinous and soil-stored species was best from the earliest plantings (May – July; i.e. autumn to mid-winter). Seeds that were planted later (August – October; i.e. late winter to spring) failed to emerge in the same year and many died over the ensuing summer, leaving few propagules to emerge the next year. I also discovered that seedlings emerging later in the wet winter period showed lower survival over the first summer, presumably because they had a shorter establishment period before summe drought. This research suggests a negative impact of fire in late winter-spring with seeds either germinating but quickly dying or having to survive over summer to the following winter. Therefore, burning in winter-spring in strongly seasonal environments may present tradeoffs in the persistence of obligate seeders and resprouters. Information on fire patchiness and intensity according to season could help identify pathways of persistence for obligate seeders under such burning regimes. Integrating ecological knowledge into fire management can assist in avoiding unwanted impacts on biodiversity.