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27/10/2015

Leadbeater’s Possum – Impacts of fire

Jenny Nelson

Arthur Rylah Institute

Department of Environment, Land, Water and Planning

Leadbeater’s Possum Gymnobelideus leadbeateri

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• Small, arboreal marsupial

• Related to Sugar Glider but no gliding membrane, so leaps

• Endemic to Victoria

• Victoria’s faunal emblem

Distribution

• Restricted distribution

- 70 x 80 km in the Central Highlands

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Habitat

Montane Ash Forest

- Mountain Ash

- Alpine Ash

- Shining Gum

Sub-alpine Woodland

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Lowland Floodplain Woodland

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Habitat requirements

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• Smooth-barked eucalypts – shedding bark used for nests & foraging

Habitat requirements

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• Hollow-bearing trees – nesting and shelter

Snow Gum hollows

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Habitat requirements

• Wattle & dense well-connected vegetation for food & movement

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Ideal habitat

• Multi-aged forest

• Abundant live & dead hollow-bearing trees

• Dense mid-storey vegetation

• Wattle

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Diet

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• Plant and insect exudates (80% of diet)

- Acacia gum

- Eucalypt nectar and sap

- Sweet exudates of psyllids

• Arthropods (20% of diet)

- Tree crickets

- Beetles

- Moths

- Spiders

Conservation status

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• Particularly vulnerable to disturbances - restricted distribution - depends on hollow-bearing trees; suitable hollows take >100 years to develop - habitat subject to disturbances

• Listed under FFG Act in Victoria

- Endangered on Advisory List of Threatened Vertebrate Fauna

• Critically Endangered under federal EPBC Act

- Recently upgraded from Endangered

Bushfire in the Central Highlands

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• Primary form of large-scale disturbance in Leadbeater’s Possum habitat

• On average bushfire every 10 years

• Most intensive & extensive fires in 1939 & 2009

• Climate change may lead to more bushfires

1939 & 2009 bushfires, key differences

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• only known from Central Highlands • severely impacted by 2009 fires – half range burnt • not recorded in burnt habitat

• 1939 fires burnt majority of Central Highlands ash, forest now 74 years old - extensive areas of old growth prior to 1939 resulted in lots of stags

• 2009 fires burnt 34% of potential habitat - resulting dead trees too small to provide suitable hollows

Old growth Mountain Ash Forest, photo Dan Harley

Impact of fire

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• Impact of fire depends on: - intensity (how hot) - frequency (interval b/t fires) - location (where in range) - extent (area affected)

• Ash trees killed by high intensity fires leading to single-aged stands, with nesting sites in dead trees or surviving live trees

• If fire interval < 20-30 years then ash trees replaced by other species

• Promotes wattle regeneration

Impact of fire

• Extensive, high intensity or frequent bushfires increase the risk of extinction of Leadbeater’s Possum

– Possum mortality

– Loss of hollow-bearing trees

– Destruction of food resources

– Alters stand structure

– Isolates surviving populations

• Patchy or lower intensity bushfires result in multi-aged forests within which hollow-bearing trees may be retained, or can develop

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2009 Black Saturday bushfires

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• 2009 fires burnt 34% of range of Leadbeater’s Possum

• No possums found in burnt habitat - ANU, 161 long-term monitoring sites, no possums on 68 burnt sites - Zoos Victoria, 95% known population killed on Lake Mountain - ARI, 180 sites surveyed in 2012, no possums on 30 burnt sites

• Surviving populations fragmented

2009 bushfire & Leadbeater’s Possum records

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Sub-alpine woodland burnt in 2009

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Montane ash forest burnt in 2009

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ARI – Forest Biodiversity Project

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• Improve knowledge of distribution & habitat use of priority threatened fauna to inform management

• Broad-scale survey to locate priority areas for Leadbeater’s Possum - 180 survey sites throughout range - developed occupancy model to predict strongholds

• Persistence of colonies in ‘fire refuges’ - surveyed 37 unburnt patches within the 2009 fire area

Predicted strongholds post-2009 fire

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Recovery potential in bushfire area

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• Unburnt patches within 2009 fire area

• 37 refuges surveyed

• Recorded at 6 sites (16%)

• Important for future recolonisation of burnt area

Fire management

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• Incorporate known colonies & high quality habitat into fire operations & risk landscapes planning

• No fuel reduction burning in Leadbeater’s Possum habitat

• Active fire management activities to reduce risk of bushfire impacting on known colonies & high quality habitat

• Develop bushfire recovery protocols

Managing bushfire risk

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• Phoenix Rapidfire – bushfire simulation tool

- predict risk to Leadbeater’s Possum habitat & known colonies

- where to target management to reduce bushfire risk

Bushfire recovery protocols

• Management actions that may be undertaken post-bushfire to assist recovery of known colonies

• Aim to improve key habitat requirements:

- availability of den sites

- vegetation connectivity

- food

• Depends on location & significance of known colonies, severity of fire & current management

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