Lantana camara poses a serious threat to the biodiversity of dry rainforest vegetation at Forty Mile Scrub National Park in Queensland, Australia. In areas of recent disturbance or open canopy, it can form dense thickets that are able to out-compete native species. High densities of L. camara have also been associated with an increase in the frequency and intensity of forest fires, which kills native dry rainforest species and promotes further invasion by L. camara. This study tests three common weed control methods for their effectiveness in removing L. camara, their threat to native species, and their success in reducing L. camara fuel loads. In doing so, this study aims to provide an ecosystem-specific management plan for a weed that has been shown to drastically reduce biodiversity. The removal of L. camara and the threat to native species were quantified by counting the numbers of dead and live L. camara plants and native species, and the effects of the treatments on L. camara fuel loads are evaluated through biomass and fuel height comparisons. The three weed control treatments were hand pulling, foliar spraying with a glyphosphate herbicide, and a basal bark application of a picloram and triclopyr based herbicide.  

Results/Conclusions

The foliar spray herbicide was the most effective in removing L. camara. The number of individuals of native species killed did not differ between herbicide treatments. While small sample sizes meant that there were no differences between treatments in the amount of biomass of L. camara in cubic meter samples, a significant positive correlation was found between the average fuel height of the L. camara plants and the biomass in these cubic samples, suggesting that fuel height was an appropriate surrogate measure for L. camara biomass. Hand pulling resulted in the largest decrease in the fuel load height, and thus most effectively reduces the fuel load. Finally, the results and subsequent cost analysis were used to develop a Forty Mile Scrub NP L. camara control plan. This plan recommends hand pulling to be utilized in the creation of a fire buffer along the perimeter of the park to reduce the fuel load in fire-prone areas, as well as along scenic paths to reduce native species deaths in areas available to recreational visitors. Due to its high efficiency and low costs, the foliar spray is recommended for the remainder of the park targeted for L. camara treatment.