Where there's smoke, there's fire

Dr Ben Miller (Research Scientist), Dr Russell Miller (Research Scientist), Ebony Cowan (PhD Student)

Fire is critical to the ecology of many Australian ecosystems. Many plant species have developed adaptations that promote regeneration following fire and, therefore, fire has the potential to be a useful tool for restoration.

Understanding fire ecology and fire risk has been a key focus of Kings Park’s research program and is becoming more important as the need for ecological restoration increases.

Kings Park Science staff monitor a research burn that will help inform future fire and weed management decisions. Photo: Russell Miller

Fire as a key ecological process

Germination, flowering and seed production are closely linked to fire in many Australian plant species. Research at Kings Park has shown the effect of smoke and heat on overcoming seed dormancy and promoting germination in many native species. This knowledge has often proved critical to improving the use of seed in revegetation and restoration.

Understanding the role of fire in the ecology of ecosystems and species is useful for developing techniques for restoration.

Our research on Mason’s Darwinia (Darwinia masonii) a threatened shrub restricted to a small area with active mining projects on the semi-arid edge of the south-west illustrates how a better understanding of the role of fire can help conserve or restore populations.

We found that, despite the infrequent occurrence of fire where it occurs, this long-lived species has a long-lived seedbank which does not establish seedlings in the absence of fire (or soil disturbance). Understanding this helps set realistic expectations for population growth and generation times in conservation.

Fire in weed-invaded ecosystems

Fire is a key part of the life cycle for many native species, however, it can also promote the regeneration and spread of non-native species such as Veldt Grass (Ehrharta calycina).

Rapid post-fire regeneration of grassy weeds in otherwise non-grassy ecosystems can enhance the spread of frequent fire, further favouring weedy species and leading to a selfperpetuating and degrading grass-fire cycle.

Long-term research by Kings Park scientists and land managers, in collaboration with local councils, DBCA’s Parks and Wildlife Service and the Department of Fire and Emergency Services, is assessing the effects of fire and weed control treatments in urban bushlands.

Contrasting outcomes of intensive weed control (left half of photo) vs deliberately uncontrolled (right half) treatments following a research burn in Bold Park bushland. Photo: Ben Miller

Trials of different treatment options are providing evidence that can help inform the management of urban and agricultural ecosystems prone to weed invasion. Initial results indicate that a balance between fire and weed control can help conserve native plant diversity and manage fire risk. Burning, whether planned or unplanned, without follow-up weed management is likely to lead to ecosystem degradation and increased fire hazard in urban bushlands.

Fire in post-mining restoration

Kings Park’s fire ecology research is also investigating the role of fire in restored ecosystems. Ecological resilience – the ability of restored ecosystems to persist following a disturbance such as fire – is a desirable outcome for restoration projects, but rarely assessed. Restoration projects which enable ecological resilience can ultimately support long-term persistence of biodiversity.

PhD student Ebony Cowan (Murdoch University) is investigating whether post-mining restored banksia woodlands of different ages demonstrate ecological resilience to fire at Hanson Heidelberg Cement Group’s Gaskell sand mine near Ellenbrook in Perth’s northern suburbs. By studying restoration ages between three and 26 years, Ebony hopes to understand different plant responses to fire and determine if, and at what age, resilience to fire is established.

PhD student Ebony Cowan burns select species in post sand mining restoration to assess their recovery via resprouting. Photo: Russell Miller

A research burn in post-sand mining banksia woodland restoration to assess the resilience of the restored plant community. Photo: Ebony Cowan

A breakthrough in the 1990s identified smoke as a germination stimulant for many native plant species. Ebony used this stimulant to assess fire-related germination cues of soil seedbank communities in restoration sites of different ages. Species that normally resprout following fire were also selectively burnt to assess whether there is a size threshold for recovery via resprouting.

Plastic sheeting that forms a ‘smoking tent’ is used to stimulate seed germination to assess the composition and abundance of the species-rich soil seed bank. Photo: Russell Miller

The stats

5 experimental fires assessing fire and weed treatment effects

97% lower Veldt Grass density with post-fire weed control

198 plots in a post-fire and weed control monitoring network

106 banksia woodland species emerged following smoke tent treatment

1200+ species from 80 genera respond to smoke