Recovery of Mountain Plum-Pine Shrubland After Wildfire (Cobberas)
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Arthur Rylah Institute for Environmental Research Technical Series Report No. 153 Recovery of Mountain Plum-Pine Shrubland After Wildfire (Cobberas) Arn Tolsma, Fiona Coates & Geoff Sutter December 2004 Arthur Rylah Institute for Environmental I Research Technical Report No. 153 Mountain Plum-pine Recovery Published by the Victorian Government Department of Sustainability and Environment Melbourne, December 2004 © The State of Victoria Department of Sustainability and Environment 2004 This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. ISBN 1 74152 086 X ISSN 0810-5774 For more information contact the DSE Customer Service Centre 136 186 Front cover: Mountain Plum-Pine (Podocarpus lawrencei) on Cleft Peak, eastern Victoria. Disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Citation Tolsma, A, Coates, F. and Sutter, G. (2004) Recovery of Mountain Plum-Pine Shrubland After Wildfire (Cobberas). Arthur Rylah Institute for Environmental Research Technical series Report No. 153. Department of Sustainability and Environment, Victoria, Melbourne. II Technical Report No. 153 Mountain Plum-pine Recovery Contents Contents ........................................................................................................................ III List of Figures and Tables............................................................................................... IV Executive Summary..........................................................................................................V Introduction ..................................................................................................................... 6 Methods ............................................................................................................................ 9 Results and Discussion ................................................................................................... 11 Management Implications.............................................................................................. 20 Acknowledgments .......................................................................................................... 23 References...................................................................................................................... 24 III Technical Report No. 153 Mountain Plum-pine Recovery List of Figures and Tables Figures Figure 1. Mountain Plum-Pine (Podocarpus lawrencei). ...................................................................6 Figure 2. Distribution of Podocarpus lawrencei in Victoria .............................................................7 Figure 4. Podocarpus population ‘PLAW3’ at Cleft Peak. This population was mostly unburnt, with only minor scorching at the edges. .................................................................... 13 Figure 5. Podocarpus population ‘PLAW7’ at Cobberas 1. Only around 10% of this population remained unburnt, with 80% currently showing no signs of regeneration. ... 14 Figure 6. Podocarpus population ‘PLAW11’ at Middle Peak. This population was only burnt in one small corner........................................................................................................................... 14 Figure 8. Burnt Podocarpus at the edge of a community at Moscow Peak. Fire intensity was almost always higher at the margins than within the community. ....................................... 17 Figure 9. Dead Podocarpus in the centre of a community at Middle Peak, with fire intensity only sufficient to burn the bark. ................................................................................................... 17 Figure 10. Resprouting from epicormic buds on lower branches at Cleft Peak........................ 18 Figure 11. Resprouting from epicormic buds on a lightly scorched, small specimen of Podocarpus at Cleft Peak................................................................................................................. 18 Figure 12. Three year-old resprouts on a Podocarpus that was burnt at Cleft Peak in April 2001, highlighting the low growth rate. ...................................................................................... 19 Figure 13. Podocarpus seedlings under scorched shrubs at Moscow Peak ................................ 19 Figure 14. Podocarpus seedling at Moscow Peak. Root resprouts were outwardly similar, but lacked the soft, white root tissue.................................................................................................. 20 Figure 15. Hoof damage from horses among rocky outcrops at Moscow Peak. ....................... 21 Tables Table 1. Summary data for 25 populations of Podocarpus lawrencei in the Cobberas area, eastern Victoria. .............................................................................................................................. 11 IV Technical Report No. 153 Mountain Plum-pine Recovery Executive Summary Populations of Mountain Plum-Pine (Podocarpus lawrencei), ranging in size from around 10 m2 to 3000 m2, were assessed at five peaks on the Cobberas Range, eastern Victoria in March 2004 under the Victorian Bushfire Recovery Program. The aims were to determine the extent of damage to the populations from the 2003 alpine fires, the mode and success of regeneration, any threats that might act upon that regeneration, and to identify urgent management actions. The proportion of each population killed varied substantially, ranging from zero to 95%. The total proportion killed at each of the five peaks ranged from 2% to 63%, with an overall average of 28%. Podocarpus did not carry fire with the same intensity as adjacent shrubby vegetation, but it was sufficiently sensitive to fire that burning of the bark at the base of the trunk caused plant death. Regeneration of scorched plants was occurring, albeit at low levels, through resprouts on the trunks and branches, and occasional root resprouts. Sprout location was directly related to the intensity with which individual plants were burnt or scorched. Small numbers of seedlings were present, ranging in size from around 2 to 6 cm. Fire management plans to protect the remaining populations are recommended, along with continued rabbit control. Weeds do not currently pose a threat. However, periodical monitoring of weeds and other factors that might affect on-going regeneration success is recommended. V Technical Report No. 153 Mountain Plum-pine Recovery Introduction The Mountain Plum-Pine Podocarpus lawrencei (Figure 1) is the only native conifer occurring in the wet forests and alpine areas of mainland eastern Australia (Gibson et al. 1995). Figure 1. Mountain Plum-Pine (Podocarpus lawrencei). Clockwise (from top left); growth habit, female seed, male cones, male cones on branch, leaves. Source: Viridans Biological Databases and Andy Blackburn. This small-leaved conifer, with separate male and female plants, is widespread as a small to medium shrub of rocky areas in alpine and sub-alpine areas of Victoria (Figure 2), Tasmania and New South Wales. In exposed areas the species is often procumbent, hugging the face of glacial moraines, rock screes and outcrops. Where larger rocks afford adequate protection it may occur as a spreading shrub up to 2 metres tall. Very occasionally the species (or plants with close affinities) is found as a large shrub or small tree (up to 20 metres tall) in subalpine woodland (such as at Echo Flat, Lake Mountain) or in montane wet forest (Goonmirk Rocks on the Errinundra Plateau (Podocarpus spp. aff. 6 Technical Report No. 153 Mountain Plum-pine Recovery nov.) and a site on the Mersey River in Tasmania). These non-alpine occurrences have generated much interest as to the age of the plants and their taxonomic, genetic and ecological significance. The likely fire history of such sites is of particular interest, as the species is usually considered to be both slow growing and sensitive to all but the lowest intensity fires (Barker 1991). Indeed, growth rates are so slow that a 170-year old specimen near Mt Kosciuszko was recorded with a trunk diameter of only 6 cm (ANBG 2003). Figure 2. Distribution of Podocarpus lawrencei in Victoria (Source: Viridans Biological Databases). Alpine vegetation communities dominated by Podocarpus lawrencei are thought to be pioneers of scree slopes (Costin et al. 1979) and the protection provided by the shrub may be important in the colonisation of this habitat by many plants and animals. Most notably, the endangered Mountain Pygmy-Possum (Burramys parvus) relies heavily on this habitat for shelter and food. Due to its restricted range and importance, Mountain Plum-Pine Shrubland is potentially a threatened community in Victoria. 7 Technical Report No. 153 Mountain Plum-pine Recovery The extensive fires in eastern Victoria and southern New South Wales of January-February 2003 burnt a large part of the Mountain Plum-Pine’s mainland range, raising concerns about the species survival and regeneration over large areas. The ability of the community to recover from fire is relatively unknown, although seedlings and basal resprouts were observed after a fire on the Cobberas Range in April 2001