Weed invasion increases after large-scale wildfires in remote alpine areas in Eastern Australia

Abstract

Both weed invasion and large-scale fires have been infrequent in alpine habitats, however there is evidence that both are increasing in frequency, resulting in losses to biodiversity and ecosystem health. We investigated the impact of a recent large wildfire on weed invasion in a remote area within Kosciuszko National Park in New South Wales, Australia. We were particularly interested in the responses of an emerging weed, Pilosella aurantiaca spp. aurantiaca (orange hawkweed) as it is being intensely managed for eradication. Despite relatively little human disturbance in these remote areas, at least 16 invasive species were recorded establishing post-fire, while unburnt sites only recording four species. At burnt sites, the increase in weed invasion may be from seed stored in the soil seed bank taking advantage of the open environmentor it could be from seed dispersed into the site from roadside plants. P. a. spp. aurantiaca was able to come back at sites post-fire but establishment appeared hampered by particularly hot fires at those sites where recent presence of the species had not been recorded. This work identified that there is an increase in weed invasion in these high-altitude ecosystems which may be facilitated by increases in the frequency and intensity of fires. Reducing propagule availability through the reduction of source plants along roadsides and managing seed-hygiene protocols for hikers will be essential actions to limit weed invasion into these remote areas.