Fire is regularly used as a purported means of protecting life and property against uncontrolled wildfire. But does it work?
Haslem et al (2011) warned that we cannot manage fires beneficially without first knowing how litter behaves over long periods after fire. Now, with data gathered in time-since-fire measurements of litter tonnage per hectare (t/ha), interviews with long-term residents, historical family property records and collected materials from other earlier studies, research finally proves that burning vegetation along prescribed 30 year interval guidelines (Department of Environment and Conservation 2005/DECC 2008) based solely on an expected response to fire by plants, is less successful in protecting life and property than leaving it alone (Croft; Hunter, Reid University of New England / Office of Environment and Heritage 2016)
Observant landowners already know that fire brings only a denser layer of dropped leaves, dead sticks, fallen trees and elimination of soil moisture, fungus and organic mulch, all set for a hotter fire the next year.
In line with these views, it is now known that litter loads ('fuel' in human terms) in forests unburned for greater than 100 years pose less threat than occasionally burned areas. Also, on frequently burned sites, leaf and bark build-up is significantly greater (about 10 t/ha) than where fire is removed from the landscape.
Depending on soil and moisture, litter after fire builds up over 20–30 years to around 4–8 t/ha. It then stabilises for a further 10 or so years, then declines with an increase in humidity, fungus and soil creation. In forests unburned for greater than 100 years, litter mass remains generally constant at less than 2 t/ha. Similarly shrub cover increases rapidly in the first 10 years after fire, continues a more gradual increase up to 15–20 years, then declines, eventually reverting to its original balance beyond 100 years.
As ground litter does not, after all, continue to build up ad infinitum, as believed, the prescribed 30 year cycle fire regime is not only ineffective (Whelan 2002; Fernandes and Botelho 2003), but actually detrimental to long-term protection.
Land managers who leave forested areas alone are ensuring a much safer environment for themselves, their neighbours, and their following generations.
- Patricia Edwards
This article was originally published in the VOICES FOR THE EARTH column in The Daily Examiner on October 10, 2016