Recovery of Mountain Plum-Pine Shrubland After Wildfire (Cobberas)

Arthur Rylah Institute for Environmental Research

Technical Series Report No. 153

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

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 (Edwards 2003).

This project was identified in the Statewide Public Land Ecological and Cultural Fire Recovery Plan (Parks Victoria and Department of Sustainability and Environment 2003). The objectives of the project were:

• Identify threats currently and potentially acting on the community in the Alpine National Park along the Cobberas Range,

• Identify urgent management requirements

• Provide baseline information to monitor progress of key species or communities toward recovery.

In particular, threats related to the grazing and browsing by both native and pest animal populations were to be considered when identifying management recommendations.

8 Technical Report No. 153 Mountain Plum-pine Recovery

Methods

The peaks commonly referred to as the Cobberas Range are situated in the far east of Victoria, close to the headwaters of the Murray River (Figure 3), and range in altitude from 1640 m to 1830 m. The geology consists mostly of igneous extrusive rocks dating from the Lower Devonian, such as rhyodacite, andesite, basalt and rhyolite (LCC 1977). The region has mean annual precipitation of around 1600 mm (much of it as snow), and mean minimum to maximum daily temperatures of around 1º to 11º in winter, and 9º to 26º in summer (Australian Bureau of Meteorology).

Field assessments of the Mountain Plum-Pine Podocarpus lawrencei populations on five peaks of the Cobberas area were undertaken from 20 to 24 March 2004:

• Cleft Peak (1760 m)

• Middle Peak (1760 m)

• Cobberas No. 1 (1830 m)

• Cobberas No. 2 (1720 m)

• Moscow Peak (1640 m)

All populations assessed were recorded on sketch maps and the approximate boundaries of the population recorded using a handheld GPS unit. The following data were recorded for each population:

• Proportion of Podocarpus plants ‘killed’ by recent fire (not presently showing signs of regeneration)

• Proportion of Podocarpus plants scorched but not killed by the fire

• Proportion of Podocarpus plants unburnt

• Presence of resprouting from the base or branches of scorched shrubs

• Presence of Podocarpus seedlings

It was initially anticipated that individual resprouting plants and seedlings would be recorded for future monitoring. However, the large number of resprouts and very small numbers of seedlings were deemed to make monitoring impractical given the time and budget of this and likely future projects.

In addition to ground based monitoring, oblique aerial photographs were taken of selected populations. These were not utilised for the current report, but might be able to assist future monitoring or mapping. The approximate location of each photograph was recorded using a GPS unit.

9 Technical Report No. 153 Mountain Plum-pine Recovery

2 km

Figure 3. Cobberas Ranges showing locations of areas searched and populations assessed.

10 Technical Report No. 153 Mountain Plum-pine Recovery

Results and Discussion

Approximately 30 - 40 Podocarpus lawrencei populations were located in the Cobberas area, ranging in size from as little as 1 m2 to around 3000 m2. The largest individual populations were located on Cleft Peak, with high cover noted within the cleft and on the southern flanks. The great majority of plants were located on rocky slopes or outcrops of a southerly (south-west to south-east) aspect. There were few populations with a more northerly aspect, the exception being a minor occurrence at Cleft Peak.

The locations and spatial extent of all populations were recorded (Table 1), with the exception of some on Cobberas 2, where numerous small populations were widely scattered over inaccessible terrain. The assessment at this site was somewhat restricted but was nevertheless sufficient to capture most of the area covered by the species.

Table 1. Summary data for 25 populations of Podocarpus lawrencei in the Cobberas area, eastern Victoria. Note that blank values for the presence of seedlings or resprouts do not indicate definitively that they were absent, as it was often not possible to closely examine sites on rocky outcrops or readily access the centre of large burnt patches.

Site name Location Area (m2) % Unburnt % Scorched % Killed Seedlings Resprouts

PLAW01 Cleft Peak 400 0 5 95 none minor

PLAW02 Cleft Peak 100 0 80 20

PLAW03 Cleft Peak 900 90 10 0

PLAW04 Cleft Peak 350 90 5 5

PLAW05 Cleft Peak 3000 50 30 20

PLAW16 Cleft Peak 500 95 5 0

Cleft Peak Average 59 22 19

PLAW06 Cobberas 1 30 95 0 5

PLAW07 Cobberas 1 500 10 10 80 some some

PLAW08 Cobberas 1 130 70 15 15 9

PLAW09 Cobberas 1 60 95 3 2

PLAW10 Cobberas 1 50 100 0 0

Cobberas 1 Average 36 9 55

PLAW20 Cobberas 2 10 100 0 0

11 Technical Report No. 153 Mountain Plum-pine Recovery

PLAW21 Cobberas 2 10 80 20 0 some

PLAW22 Cobberas 2 300 70 20 10

PLAW23 Cobberas 2 500 95 5 0 some

PLAW24 Cobberas 2 1500 90 10 0

PLAW25 Cobberas 2 500 90 5 5

Cobberas 2 Average 89 9 2

PLAW11 Middle Peak 750 95 3 2

PLAW12 Middle Peak 100 80 10 10 some

PLAW13 Middle Peak 1500 0 5 95 minor

PLAW14 Middle Peak 370 0 30 70 many

PLAW15 Middle Peak 80 0 30 70 minor

Middle Peak Average 28 9 63

PLAW17 Moscow Peak 200 60 20 20 36 some

PLAW18 Moscow Peak 30 50 25 25 20 none

PLAW19 Moscow Peak 30 75 25 0

Moscow Peak Average 61 21 18

Total Average 57 15 28

The data showed substantial variation in the extent to which populations were affected by the fire (Figures 4 – 7):

• Proportion unburnt ranged from 0 to 100%

• Proportion scorched but not killed ranged from 0 to 80%

• Proportion killed ranged from 0 to 95%.

On average, around 57% of the Podocarpus dominated communities (by total area) remained unburnt, 15% was scorched but not killed, and 28% showed no signs of regeneration. However, analysis of data for the five separate areas showed that Cobberas 1 and Middle Peak had suffered proportionately greater damage as a result of the fires, with 55% and 63% respectively of the Podocarpus areas assessed having been killed. In contrast, Cobberas 2, Moscow Peak and Cleft Peak populations suffered mortality of 2%, 18% and 19% respectively.

12 Technical Report No. 153 Mountain Plum-pine Recovery

Note that assessment of the damage from the 2003 fires was confounded by the effects of a fire in April 2001, which partially burnt some communities on Cleft Peak and Middle Peak (Edwards 2003). It was not always possible to determine which fire had been responsible for killing parts of particular communities, and some percentages quoted for area killed may thus overstate the damage from the 2003 fires.

Figure 4. Podocarpus population ‘PLAW3’ at Cleft Peak. This population was mostly unburnt, with only minor scorching at the edges.

13 Technical Report No. 153 Mountain Plum-pine Recovery

Figure 5. Podocarpus population ‘PLAW7’ at Cobberas 1. Only around 10% of this population remained unburnt, with 80% currently showing no signs of regeneration.

Figure 6. Podocarpus population ‘PLAW11’ at Middle Peak. This population was only burnt in one small corner.

14 Technical Report No. 153 Mountain Plum-pine Recovery

Figure 7. Podocarpus population ‘PLAW13’ at Middle Peak. This large population was extensively burnt, with around 95% currently showing no signs of regeneration.

15 Technical Report No. 153 Mountain Plum-pine Recovery

As well as varying in extent, the fire also varied markedly in intensity from one location to another, and between vegetation types.

Individual Podocarpus plants were sometimes completely burnt at ground level where they occurred at the margins of a patch (Figure 8), but were rarely severely burnt within a patch, even where the burnt area was substantial and many plants were killed (Figure 9). This suggested that Podocarpus patches were not carrying fire with the same intensity as the vegetation around it, such as the often severely burnt adjacent patches of Tasmannia xerophila. However, it also suggested that even low intensity fires merely sufficient to burn the bark at the base of the trunk could kill Podocarpus.

Where the fire had been less intense, many individual plants were resprouting from buds under the bark, and these were variously observed on the lower trunk, larger branches (Figure 10), or even smaller branches (Figure 11). Resprout location was directly associated with fire intensity, and only plants that were lightly scorched were able to regenerate from buds on smaller branches. No resprouting shrubs were observed when the bark had been burnt at the base of the trunk.

Some older resprouting was noted at Cleft and Middle Peaks, where portions of some communities had been burnt in the fire of April 2001. The size of the 3-year-old resprouts in Figure 12 demonstrates just how slowly Podocarpus lawrencei grows in this environment.

Seedlings ranging in height from around 2 to 6 cm were noted (Figures 13 & 14), but the quantity and spatial distribution varied substantially between sites. Many small sites on rocky outcrops were difficult to examine closely, and the time available precluded closer examination of the centres of many larger patches. The work was also hampered by the difficulty in negotiating through such badly burnt communities.

Some populations appeared to entirely lack seedlings. It is not clear whether this is due to a naturally small seedbank in the soil and leaf litter, or to a limited amount of fruiting and seed dispersal by birds since the fire. Birds are considered to be the main agent of dispersal in Podocarpus lawrencei (Bowman & Harris 1995) and, as leaf litter and thin soil still exist under and around burnt plants, or in gaps between boulders, seedling recruitment is likely to continue slowly over time.

One individual at Middle Peak was observed resprouting from the roots of an adult plant. However, it was not possible to routinely distinguish root resprouts from seedlings without causing unneccesary disturbance to the limited number of individuals present. An unknown proportion of the individuals classified as seedlings in this report might therefore be resprouting from root buds.

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.

Figure 9. Dead Podocarpus in the centre of a community at Middle Peak, with fire intensity only sufficient to burn the bark. The trunk diameter of this plant was around 30 cm.

Technical Report No. 153 Mountain Plum-pine Recovery

Figure 10. Resprouting from epicormic buds on lower branches at Cleft Peak.

Figure 11. Resprouting from epicormic buds on a lightly scorched, small specimen of Podocarpus at Cleft Peak.

Figure 12. Three year-old resprouts on a Podocarpus that was burnt at Cleft Peak in April 2001, highlighting the low growth rate.

Figure 13. Podocarpus seedlings under scorched shrubs at Moscow Peak

Technical Report No. 153 Mountain Plum-pine Recovery

Figure 14. Podocarpus seedling at Moscow Peak. Root resprouts were outwardly similar, but lacked the soft, white root tissue.

Management Implications

Fire protection

Podocarpus lawrencei, as with other Australian heathy conifers, does not require the intervention of fire to persist across its range (Kirkpatrick 1983), although it can respond to disturbance and has a long recruitment phase (Barker 1991). Indeed, some fire protection is afforded by its rocky habitat, which does not appear to carry as intense a fire as adjacent shrub communities such as those dominated by Tasmannia xerophila. Fires (or at least high intensity fires) that could severely affect Podocarpus communities are likely to have been historically rare. A patch of vegetation at Cleft Peak appeared to be regenerating from a fire that occurred perhaps 40-50 years ago, but the presence of individual plants with trunk diameters up to around 30 cm at Middle Peak suggests that some populations have not experienced fire for hundreds of years.

Nonetheless, some 3300 m2 of Podocarpus community was killed across the five main peaks during the 2003 fires, including some large, old plants that will take many decades to replace. A subsequent fire would severely impact on the recovery of these populations. This could be by a reduction in the local seed source that is crucial for dispersal and recruitment,

or by the killing of resprouts on scorched plants before those plants have recovered their energy reserves in the form of photosynthates.

A Fire Protection Plan that aims to prevent fire from reaching the remaining communities and ensures that the remaining Podocarpus populations are protected in the foreseeable future is therefore a crucial part of any management strategy for the Cobberas region.

Grazing

Feral horses are present in the area around the Cobberas, and signs of hoof damage were seen in some surprisingly steep and rocky areas (Figure 15). No evidence of damage by horses or other livestock was noted in the Podocarpus dominated communities and regeneration may not be affected. Nonetheless, this should be monitored.

Figure 15. Hoof damage from horses among rocky outcrops at Moscow Peak.

Technical Report No. 153 Mountain Plum-pine Recovery

Rabbits were seen in the study area particularly around Cobberas 1, and pose a direct threat to regeneration. Rabbits shelter in the thickets, and browse on seedlings or resprouts with their higher nutrient content. Given the slow growth rates of seedlings and resprouts, and a prolonged recruitment and regeneration phase, long-term rabbit control is necessary. Some rabbit control measures have already been implemented (P. Rennick, PV pers. comm.), but further control and on-going monitoring should be maintained.

Weeds

The crowded growth structure of Podocarpus heath provides little scope for other species to live beneath mature foliage, ensuring that it forms a virtual monoculture. No weeds were noted within the Podocarpus communities, but weeds observed in grassy areas away from the outcrops included Clover (Trifolium spp.), Sheep Sorrel (Acetosella vulgaris) and Cat’s Ear (Hypochoeris radicata). Weeds such as Plum (Prunus spp.), Shasta Daisy (Leucanthemum maximum) and Columbine (Aquilegia vulgaris), which are considered to be possible threats in other high-altitude heathland areas, were not found.

Weed establishment and persistence would depend heavily on both the availability of propagules and the on-going regeneration success of the Podocarpus shrubs, but at this stage weeds are not considered to represent a threat. In any event, active weed control of highly scattered populations in this remote location would be logistically difficult. Nonetheless, periodical monitoring is needed to detect any unforeseen outbreak and thus allow early intervention.

Future monitoring

The remote location of the Cobberas and difficulties in accessing the sites make regular monitoring of individual plant recovery (via seedlings or resprouts) impractical. However, some long-term monitoring of overall community response and regeneration success should be planned, to determine whether any factors are affecting that regeneration. Of most concern are:

• sequential fires that can kill regeneration or limit dispersal of seeds

• rabbits or other herbivores targetting the fresh regrowth or seedlings

• outbreaks of weeds, particularly competitive woody species

Monitoring, and prompt remedial action if necessary, will ensure that this limited and important vegetation type can recover and persist in the future.

Acknowledgments

The authors are grateful to Jenny Edwards for providing observations and maps of Podocarpus stands and to Dale Tonkinson (Arthur Rylah Institute) for introductory information. Steve Fall, Ben Rankin and Tim Crawford (DSE Forestry Swifts Creek) provided valuable site information. Brian Reese and staff (DSE air desk) arranged helicopter transport and DSE staff at Swifts Creek assisted with re-fuelling.

The project was funded under the Victorian Bushfire Recovery Program (DSE and Parks Victoria).

Technical Report No. 153 Mountain Plum-pine Recovery

References

ANBG (2003) http://www.anbg.gov.au/gnp/interns-2003/podocarpus-lawrencei.html

Barker, P.C.J. (1991) Podocarpus lawrencei (Hook. f.): Population structure and fire history at Goonmirk Rocks, Victoria. Australian Journal of Ecology 16, 149-158.

Bowman, D. M. J. S. and Harris, S. (1995) Conifers of Australia’s dry forests and open woodlands. In Enright, N.J. and Hill, R.S. (Eds) Ecology of the Southern Conifers. Melbourne University Press, Melbourne.

Costin, A.B, Grey, M., Totterdell, C.J. and Wimbush, D.J. (1979) Kosciusko Alpine Flora. CSIRO/Collins, Melbourne.

Edwards, J. (2003) Alpine regrowth after fire. The Clematis 55, 7-9.

Gibson, N., Barker, P.C.J., Cullen, P.J. and Shapcott, A. (1995) Conifers of southern Australia. In Enright, N.J. and Hill, R.S. (Eds) Ecology of the Southern Conifers. Melbourne University Press, Melbourne.

Kirkpatrick, J. B. (1983) Treeless plant communities of the Tasmanian high country. Procroceedings of the. Ecological Society of Australia 12, 61-77.

LCC (1977) Alpine Study Area Report. Land Conservation Council, Victoria.