Changes in the ecology and control of introduced non-native plants following pest herbivore eradication in the sub-Antarctic: Stellaria media
- Monitor changes in populations of palatable invasive non-native plants that most threaten the recovery of ecosystem structure and function on Macquarie Island following the eradication of rabbits, rats and mice; and
- Determine whether the ecology of the weed species with most limited distribution, Stellaria media, is conducive to its management or eradication in this early post-herbivore period.
Data on this dicotyledonous weed will complement that collected by our team on the widespread sub-Antarctic grass, Poa annua.
By understanding these issues, we will assist in the development of effective, low-impact control options for island management and sub-Antarctic and international plant eradication programs.
Three data collection periods on Macquarie Island, and experimental activities at UNE.
- Literature review.
- Distribution, cover and plant size mapping, and detailed vegetation surveys at several infested sites.
- Random seedbank sampling to characterise soil seedbank ecology.
- Seed burial to monitor longevity and viability.
- Seedlining emergence and growth: in-situ monitoring and ex-situ experiments.
- Physical control: in-situ experiments involving hand weeding, digging, cutting plants and scalping.
- Herbicide control: ex-situ experimental trials under sub-Antarctic conditions using screened herbicides.
- Herbicide soil dynamics: investigate the interactive effects of soil type, herbicide type and incubation period on herbicide fate.
- A cosmopolitan species which has spread to tropical regions of Africa, South America and Asia and to the islands of the Arctic and sub-Antarctic.
- An annual, over-wintering, or sometimes perennial herb, able to survive temperatures of -10°C.
- Prefers cool, shady, moist habitats, and well adapted to the Macquarie Island environment.
- Spreads by rooting at the nodes and forms thick, succulent mats 30-40 cm tall.
- Known to quickly enter areas disturbed by humans and animals.
- Spread has been associated with colonies of burrowing seabirds, surface nesting birds, and marine mammals in sub-Antarctic and sub-Arctic conditions.
- 45-60 °S
- Wet, windy and cold
- Depauperate flora and faunas > isolation and harsh climate
- High conservation value > wildlife, endemics, unique environments.
Macquarie Island location
- 54°30'S, 158°57'E
- Southern Ocean
- Between Tasmania and Antarctica.
Macquarie Island — natural history
- Climate: wet, windy, cold
- Biogeography: elongated, undulating plateau, oceanic origin
- Soils: peats, dry tundra
- Flora: 42 vascular plants, many bryophytes, 3 aliens
- Fauna: seals, albatross, penguins, seabirds.
Invasive species in the sub-Antartic
- Biological invasions substantially affect the structure and function of ecosystems
- Most serious threat to the conservation of the sub-Antarctic
- Over 108 alien vascular plants
- Majority are transient/persistent and restricted, some aggressively spreading and invading
- Risk of invasion increasing.