Charred and chewed chalkies: Effects of fire and herbivory on the reintroduction of an endangered wattle

Abstract

Herbivory can threaten the persistence of palatable plant species and the fauna communities dependent upon diverse and structurally complex post-fire regeneration. This study compared the introduction success of the nationally Endangered Chalky Wattle (Acacia cretacea) in the South Australian mallee under different fire and browsing treatments. Recruitment from both seed and seedlings was enhanced by fire and was absolutely conditional on protection from herbivory, even though domestic stock were excluded and numbers of kangaroos, goats and rabbits were lower than regional averages. Several other fire-responsive plant species, including the ecologically important Porcupine Grass or spinifex (Triodia irritans), which provides habitat for threatened fauna, also benefited from herbivore exclusion. Conservation of wild populations of Chalky Wattle and other palatable fire-responsive plants, and the ecosystem processes they enable, is likely to be conditional on significant and sustained reduction in herbivore populations, especially kangaroos, following wildfires or control burns in the mallee.