Summary
Poa annua is the most widespread alien species in the sub-Antarctic, occurring on all major island groups and is invasive and spreading on the Antarctic Peninsula. P. annua colonises areas disturbed by human activity, seal wallows, penguin rookeries and glacial moraines. It also invades native communities and competes with native species. P. annua can withstand heavy grazing enabling it to significantly expand on islands inhabited by alien herbivores. It has a restricted distribution on Heard Island but is common and widespread on Macquarie Island, Australia's two World Heritage Areas. With the call for removal of non-native plants in Antarctica by the Committee for the Environmental Protection, investigating management strategies of this invasive plant is important. Our study aims to investigate the ecology and management strategies for P. annua to assist in development of non-native plant management in the sub-Antarctic and Antarctic and further our knowledge of invasion biology in the region. The results of this study will assist in the development of rapid response techniques for managing future non-native plant incursions in the sub-Antarctic and Antarctica. In situ and ex situ experiments investigating the response of P. annua and native species to manual disturbance are underway and herbicide efficacy and selectivity on P. annua and native sub-Antarctic grasses is being assessed. Herbicide movement and persistence in sub-Antarctic soils is also being measured. We are quantifying pereniality, seed longevity, seed viability and the soil seed bank. Preliminary results indicate that on Macquarie Island P. annua exhibits a perennial growth form and has an abundant seed bank in the top 5 cm of the soil. Seeds have high viability but low longevity. Initial studies indicate that Glyphosate, Rimsulfuron and Trifloxysulfuron selectively control P. annua under sub-Antarctic climatic conditions. This work aims to improve management of non-native species in the sub-Antarctic and Antarctic by investigating how invasive species perform, and the impacts of management techniques in the sub-Antarctic and Antarctic terrestrial environments.