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Australian Journal of Botany Australian Journal of Botany Society
Southern hemisphere botanical ecosystems
RESEARCH ARTICLE (Open Access)

Limited evidence for the use of livestock for the conservation management of exotic plant cover

David J. Eldridge https://orcid.org/0000-0002-2191-486X A F , Ian Oliver B C , James Val D and Samantha K. Travers E
+ Author Affiliations
- Author Affiliations

A New South Wales Department of Planning, Industry and Environment, c/- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.

B New South Wales Department of Planning, Industry and Environment, PO Box 1477, Gosford, NSW 2250, Australia.

C School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.

D New South Wales Department of Planning, Industry and Environment, PO Box 363, Buronga, NSW 2739, Australia.

E Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.

F Corresponding author. Email: d.eldridge@unsw.edu.au

Australian Journal of Botany 68(2) 137-145 https://doi.org/10.1071/BT19183
Submitted: 25 November 2019  Accepted: 12 April 2020   Published: 6 May 2020

Journal Compilation © CSIRO 2020 Open Access CC BY-NC-ND

Abstract

Livestock grazing has been used for conservation management in some situations to reduce exotic plant cover, but supporting empirical evidence is scant. This is particularly true for eastern Australian semiarid woodlands and forests. We surveyed 451 sites across three broad semiarid vegetation communities (cypress pine, black box, red gum) in eastern Australia to examine the effects of recent and longer-term (historic) grazing by livestock on exotic (and native) plant cover. Because our focus was the use of domestic livestock for conservation management, our sites were mostly located in conservation reserves, travelling stock routes and native production forests where domestic grazing is approved via permit. We also included recent grazing by kangaroos and rabbits, which occur widely with livestock across the study sites. Structural equation modelling revealed that recent sheep and cattle grazing was associated with increased exotic plant cover in two of the three communities (cypress pine, black box), and historic grazing was associated with lower exotic (and native) plant cover across all communities. Recent cattle grazing-induced reductions in exotic plant cover in the red gum community resulted from declines in the palatable exotic annual grass Ehrharta longiflora. Higher intensity grazing by rabbits, sheep and cattle in the cypress pine community increased exotic plant cover by suppressing the negative effect of native cover on exotic cover. Higher intensity rabbit grazing reinforced the negative effect of nitrogen on native plant cover, resulting in increases in exotic cover. Overall, we found strong evidence that domestic livestock grazing reduces native plant cover either directly or indirectly in all three communities, but limited evidence that it would be a useful conservation management strategy to reduce exotic plant cover in these communities.

Additional keywords: cattle, forb, grass, herbivory, rabbit, sheep, weeds.


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