The impact of introduced ship rats (Rattus rattus) on seedling recruitment and distribution of a subantarctic megaherb (Pleurophyllum hookeri)

• Published in: Austral Ecology
• Main Authors: Shaw, Justine D., Hovenden, Mark J., Bergstrom, Dana M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2005
• Subjects: Climate change; Introduced species; Megaherbs; Population recruitment; Ship rats; Subantarctic; 1105 Ecology; Evolution; Behavior and Systematics; 2303 Ecology; Buchan; Macquarie Island; Rattus rattus
• Online Access: https://espace.library.uq.edu.au/view/UQ:b929406

The impact of introduced ship rats (Rattus rattus) on recruitment of the megaherb Pleurophyllum hookeri Buchan. (Asteraceae) was examined on subantarctic Macquarie Island, an island with no extant native terrestrial vertebrates. Pleurophyllum hookeri (Asteraceae) forms a dominant component of the Macquarie Island vegetation and is restricted to the subantarctic. The Macquarie Island population of P. hookeri is the most extensive and intact. Introduced ship rats (Rattus rattus) are well established in tall tussock grassland of Macquarie Island. We detected rat activity for the first time within P. hookeri herbfields, in autumn 2000. We found rats were destroying up to 90% of racemes. By excluding rats from caches of inflorescences that they had formed, we found they were having a significant negative effect on initial recruitment and seedling survival within the caches. However, because of high seedling mortality after 1 year, there was no sustained impact of the exclosures on P. hookeri seedling density.