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Practical and theoretical implications of a browsing cascade in Tasmanian forest and woodland
journal contribution
posted on 2023-05-18, 16:01 authored by Hazeldine, A, James KirkpatrickJames KirkpatrickBrowsing cascades have strong implications for biodiversity conservation and fire management. The associational resistance and associational susceptibility hypotheses suggest different mechanisms. We tested the veracity of these two hypotheses by using small dry eucalypt forest and woodland trees. At 67 sites, we measured the height of the browse line and estimated the proportion of foliage remaining below it for all adult individuals of small trees within a 50 × 50 m area, recorded scat numbers, browsing damage to tree seedlings by species and environmental data. The 110–130-cm browse line, and strong relationships between macropod scat numbers and the remaining foliage below the browse line, suggested that Bennetts wallabies (Macropus rufogriseus Shaw) were the main cause of umbrella-shaped trees. The browsers preferred Exocarpos cupressiformis Labill. and Bursaria spinosa Cav. At the other extreme, adult Acacia dealbata Link suffered no browsing damage. All species were browsed as seedlings. Associational resistance occurred in some species and associational susceptibility in others, with the degree of difference in palatability between alternative sources of browse possibly resolving this apparent contradiction. Low browsing pressure is likely to cause woody thickening, an increase in fire hazard and a decrease in biodiversity. Extremely high browsing pressure had no such effects.
History
Publication title
Australian Journal of BotanyVolume
63Issue
5Pagination
435-443ISSN
0067-1924Department/School
School of Geography, Planning and Spatial SciencesPublisher
CSIRO PublishingPlace of publication
150 Oxford St, Po Box 1139, Collingwood, Australia, Victoria, 3066Rights statement
Journal compilation Copyright CSIRO 2015Repository Status
- Restricted