Beneath the flames: researching the fire response of native plants

We often feel relief when we see little green seedlings emerging from the blackened ground after a fire, as we take it to be a sign of the vegetation recovering. But what do our native plants need in order to get their seeds germinating?

Pink flannel flower (Actinotus forsythii)

Native plant species have evolved with fire and have different features or behaviours that enable them to resist and persist in the event of a fire. In fact, some of them outright depend on fire to ensure their long-term survival, with fire and smoke a stimulant for breaking seed dormancy and subsequent germination.

Many threatened plants benefit from intense fires, like the endangered Manning yellow solanum and Gordon’s wattle, which both saw significant growth following the 2019–20 bushfires in NSW.

While there are always winners and losers when it comes to plants after fire, our scientists are interested in understanding the cumulative effects of fires occurring more often and burning at hotter temperatures and the interaction of other pressures, such as grazing on seedlings by hungry animals, drought and climate change. An understanding of how species respond to fire is fundamental to the conservation of native plants in Australia.

Fire for fertility

Plants have many strategies for recovery after fire. Depending on the type and temperature of the fire, some native species, such as grass trees, respond by re-sprouting. Others germinate seed that lay dormant in the soil seed bank, while some species, like banksia, take advantage of the high temperatures and smoke to crack woody seed cases and release their seed dormancy so they can take up water and germinate.

Department of Planning Industry and Environment, Senior Scientist, Dr John Porter studies ephemerals (plants with short life cycles) and says they are common in Australian flora. “Fire ephemerals are an important group of species that require fire of a specific temperature to enable germination, flowering and subsequent recruitment (the restoration of a plant population).”

”We are studying one such fire ephemeral, the pink flannel flower (Actinotus forsythii), which is entirely reliant on fires to germinate, regrow and replenish its soil seed bank."

It’s a short lived annual that is highly visible for short periods (12 months) following fire, with spectacular mass flowering of dense but highly localised populations. The flower is largely confined to high elevation heath and sedgeland on shallow rocky soils in the central and southern tablelands of NSW

“We are so fortunate to be able see masses of pink flannel flowers in bloom at the moment from Lithgow, Newnes and Katoomba in the Blue Mountains. It really is quite a spectacular sight and such a special opportunity to study them” says Dr Porter.

When it isn’t putting on incredible flowering displays, the pink flannel flower seeds are hidden in the soil seed bank, where they can remain concealed for decades until a fire releases seeds from dormancy and enables seeds to germinate.

Seed banking on the future

Information about the pink flannel flower’s population and seed ecology is helping our understanding of a related species’ fire response – the West Australian fire ephemeral, Actinotus luecocephalus.

“Actinotus luecocephalus has been found to have morphophysiological dormancy, which simply means the plant requires fire as well as time after the fire to germinate dormant seeds that lay in the soil seedbank. More than half of our native flora germinates in this way, as the wind and rain disperse seeds from afar, it can be surprising what emerges after fire” says Dr Porter.

What can make it difficult for scientists to find out more about these plants is that – while they need fire to break dormancy – they are short lived after germination. The frequency, intensity and extent of fires are increasing with climate change, impacting soil temperatures and health, as well as plants that use fire to germinate.

Our scientists and research partners look at a wide range of factors which threaten species, to find the best possible management solutions in response to changing fire regimes as a result of climate change. This research will not only help manage threats to existing plant populations but will enable modelling to determine the optimal fire regimes and temperatures for a range of fire ephemerals.

Every decision Saving our Species makes is backed up by science and research, and we fund a range of research projects to improve our knowledge of threatened species, ecological communities and threats.

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