Fire Supporting Recovery from African Olive Invasion
A field experiment conducted at Mt Annan Botanic Gardens in Western Sydney compared the use of fire treatment, direct seeding and combined treatments for early stage restoration of Cumberland Plain Woodland. African Olive (Olea europaea ssp. cuspidata), is a highly invasive dense crowned evergreen tree that has been present at the site for at least 15 years, preventing the growth of native plants in the understorey and midstorey. Peter Cuneo from the Royal Botanic Gardens and Domain Trust and Michelle Leishman from Macquarie Univerity published the results of this 3 year field experiment involving this ‘bottom up’ model of ecological restoration.
Site preparation & treatment
The site was prepared by cutting down the African Olive trees and treatment of the stumps with glyphosate, followed by chipping of the biomass which was spread across the site. A range of treatments were applied to the experimental plots including: 1) control, 2) burn, 3) sow native seed, and 4) combined burn and sow seed. The fire treatments applied to the burn plots involved a medium-hot intensity fire that was allowed to burn for 2.5 hours to ensure soil heat penetration and total fuel consumption.
Ultimately the practice of fire combined with direct seeding produced greater native species cover, less exotic species and the lowest number of established African Olives when compared to the control plots or direct seeding alone. The team concluded that fire and direct seeding “often prove more successful than would either approach alone”. This experiment and its findings may also be applicable to other degraded grassy woodland sites.
References (full article available for free download)
Cuneo, P. and Leishman, M. R. (2015), Recovery after African Olive invasion: can a ‘bottom-up’ approach to ecological restoration work?. Ecol Manag Restor, 16: 33–40. doi:10.1111/emr.12139
Details of the native seed production (external link)
Overview of African olive ecology and introduction into Australia (external link)