Ten year post-fire response of a native ecosystem in the presence of high or low densities of the invasive weed, Asparagus asparagoides
Peter J. TurnerA,B,C,E and John G. VirtueB,D
A School of Animal Biology, University of Western Australia, Stirling Highway, Crawley, Western Australia 6009, Australia.
B CRC for Australian Weed Management.
C CSIRO, Division of Entomology.
D Department of Water, Land and Biodiversity Conservation, GPO Box 2834, Adelaide, South Australia 5001, Australia.
E Present address: Pest Management Unit, Department of Environment and Climate Change, PO Box 1967, Hurstville, New South Wales 1481, Australia.
Bridal creeper, Asparagus asparagoides (L.) Druce, is a major environmental weed in southern Australia. Being a geophyte, it has annual shoot growth with a large tuberous root mat belowground. It is capable of displacing native vegetation and has been targeted for control in Australia, especially using biological control. Previous studies on the impact of this environmental weed have suggested that without further restoration, invaded areas could take many years to recover. As fire can be used as a restoration tool, given it can stimulate the regeneration of some native Australian plants, this study aimed to determine the response of a native plant community for the first ten years following a fire, with and without the presence of bridal creeper.
Following a wildfire in March 1996, plots were established in a mallee remnant in South Australia. In October 1996, bridal creeper was controlled in half the plots using glyphosate. In 2006, there was still a significant difference in the density of bridal creeper, with 33.4 ± 5.0 (mean ± SE) emerging shoots m-2 in the untreated plots compared to 9.1 ± 1.2 shoots m-2 in the controlled plots. However at the same time, there was no significant difference in the native plant assemblages or with the number of native plant species between plots with high or low density of bridal creeper, except for small shrubs, creepers and climbers which had higher cover in the untreated plots. A difference in soil nutrients was also evident. The soil where bridal creeper was not controlled had significantly higher ammonium, potassium and organic carbon, compared to where bridal creeper was controlled. This study site, in the early stages of post-fire succession, appears to be resilient to the impacts of bridal creeper and other weed species, with acacias and other native trees and shrubs dominating the site. It is therefore concluded that fire can be an important restoration tool to stimulate the regeneration of some native Australian plants and speed up the recovery of bridal creeper-invaded ecosystems, provided that bridal creeper and other weeds are kept at a low post-fire density, naturally or through targeted control.
Key words: bridal creeper, environmental weeds, soil nutrients, succession, weed impacts.
Plant Protection Quarterly (2009) 24 (1) 20-26.