Some species and genera of tall herbs that are widespread both in Tasmanian and in mainland Australian alpine vegetation are dominant or codominant over large areas in the Australian Alps, while being typically subordinate species in Tasmania. This difference has been attributed to the impact of vertebrate herbivores, which are abundant in the Tasmanian high country but rare in or absent from the higher altitudes in the Australian Alps. The present study tests the hypothesis that lack of dominance (>50% cover) of tall alpine herbs in Tasmanian alpine and subalpine areas could be at least partially caused by grazing of their reproductive parts. Both in experimental plots and a clipping experiment, tall herbs produced more flowering stems under lower grazing/clipping pressure. In the field, the greatest reduction in flowering occurred under a grazing regime of sheep plus rabbits plus native herbivores. There was no consistent difference in the number of flowering stems between rabbit-grazed and rabbit plus native-grazed areas. However, there was a significant negative relationship between the number of flower heads and wallaby scats and a non-significant positive relationship between the number of flower heads and rabbit scats, suggesting that wallabies, not rabbits, were largely responsible for flower head depletion. Many species had more flowering stems in rabbit plus native vertebrate-grazed areas than in ungrazed exclosures. Therefore, it seems possible that the effects of vertebrate herbivory on flowering may have contributed to the lack of tall alpine herbfields in Tasmania.

Item Type:	Refereed Article
Research Division:	Environmental Sciences
Research Group:	Environmental management
Research Field:	Wildlife and habitat management
Objective Division:	Environmental Management
Objective Group:	Terrestrial systems and management
Objective Field:	Assessment and management of terrestrial ecosystems
UTAS Author:	Bridle, K (Dr Kerry Bridle)
UTAS Author:	Kirkpatrick, JB (Professor James Kirkpatrick)
ID Code:	22073
Year Published:	2001
Web of Science® Times Cited:	10
Deposited By:	Geography and Environmental Studies
Deposited On:	2001-08-01
Last Modified:	2007-11-06
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