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Understorey thinning and burning trials are needed in conservation reserves: The case of Tuart (Eucalyptus gomphocephala D.C.)

Authors

  • Robert D. Archibald,

  • Jack Bradshaw,

  • Barbara J. Bowen,

  • Dugald C. Close,

  • Lachie McCaw,

  • Paul L. Drake,

  • Giles E. St. J. Hardy


  • This opinion article has arisen from studies into Tuart decline that have been funded by the Australian Research Council. The work is being continued under the Western Australian Centre of Excellence for Climate Change, Woodland and Forest Health.

Robert Archibald is a Post-Doctoral Research Fellow, School of Biological Sciences and Biotechnology, Murdoch University (South Street, Murdoch, WA 6150, Australia; Email: r.archibald@murdoch.edu.au). Jack Bradshaw is a Forest Consultant (60 Pritchard Street, Manjimup, WA 6258, Australia; Email: jbrad@karriweb.com.au). Barbara Bowen is a Lecturer in the School of Biological Sciences and Biotechnology, Murdoch University (Murdoch, WA, Australia; Email: b.bowen@murdoch.edu.au). Dugald Close is Centre Leader for Perennial Horticulture, Tasmanian Institute of Agricultural Research, University of Tasmania (Hobart, Tas. 7000, Australia; Email: Dugald.Close@utas.edu.au). Lachie McCaw is a Principal Research Scientist, Department of Environment and Conservation (Brain Street, Manjimup, WA 6258, Australia; Email: lachie.mccaw@dec.wa.gov.au). Paul Drake is a Senior Research Scientist, Natural Resources Branch, Department of Environment and Conservation (Locked Bag 104, Bentley Delivery Centre, Bentley, WA 6984, Australia; Email: paul.drake@dec.wa.gov.au). Giles Hardy is a Professor in the School of Biological Sciences and Biotechnology, Murdoch University, and Director of both the Western Australian Centre of Excellence for Climate Change, Woodland and Forest Health and the Centre for Phytophthora Science and Management, Murdoch University (Murdoch, WA, Australia; Tel: +61 8 9360 6272; Fax: +61 8 9360 6303; Email: g.hardy@murdoch.edu.au).

Abstract

Summary  Management interventions are needed to reverse the decline of Tuart (Eucalyptus gomphocephala) woodland in the Yalgorup area of south-west Western Australia where the largest intact remaining example of this ecosystem is located. Although the cause of the decline is uncertain and several factors may be involved, management action should not be withheld because the decline process is not fully understood. We contend that the reduction in fire frequency over the last 50 years has led to an increase in understorey density, particularly of Western Australian Peppermint (Agonis flexuosa), resulting in greater competition for resources, which may in turn have increased the susceptibility of healthy woodland to decline. In contrast to Tuart regeneration, which is usually tied to fire, Western Australian Peppermint can establish readily in unburnt woodland. Further, once Western Australian Peppermint seedlings develop to the lignotuberous stage, they can resprout vigorously after fire. Therefore, a combination of fire and the physical removal of understorey in sites where this species has formed extensive thickets is required to: (i) provide an opportunity for regeneration of Tuart in both healthy and declining stands; (ii) improve the chances of sustained recovery of Tuart trees in declining stands; and (iii) ensure heterogeneity in the vegetation at multiple scales, a recognized strategy for conserving biodiversity and increasing ecosystem resilience. We propose that this approach may also be relevant to other tree decline syndromes in southern Australia. However, fostering community support for active intervention using thinning and fire in conservation reserves and staging the operations within an experimental framework will be important for such action to gain both the social and scientific acceptance necessary for it to be applied widely.

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