The Tasmanian Forests and Woodlands dominated by black gum or Brookers gum (Eucalyptus ovata / E. brookeriana) ecological community is a type of eucalypt forest to woodland that is restricted to Tasmania and is associated with sites that are typically damp and/or poorly draining.
Tasmanian Forests and Woodlands dominated by black gum or Brookers gum (Eucalyptus ovata / E. brookeriana)
Status: Critically Endangered on the EPBC Act list
Government evidence of impact of climate change:
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APPROVED CONSERVATION ADVICE (INCORPORATING LISTING ADVICE) - Tasmanian Forests and Woodlands dominated by black gum or Brookers gum (Eucalyptus ovata / E. brookeriana)
Over the long term; resilient; intact ecosystems are more likely to retain their services plus adaptive capacity to sustain production of these services in the face of environmental disruptions; such as climate change.
Also; environmental variables; such as climate (and the ecological community s response to them); fluctuate or change over time.
Potential impacts of climate change; including altered fire and flooding regimes; decline in tree health due to prolonged drought and heat stress; exacerbating proliferation of invasive species and poor regeneration and recruitment of native species.
Seed collection; propagation and other ex situ recovery action. o Use locally collected seed where available to create an appropriate canopy and diverse understorey; however; choosing sources of seed closer to the margins of their range may increase resilience to climate change. o Ex situ seed banks provide an important capacity for medium to long term storage of diaspores of threatened plant species.
Patterns of increasing storm and lightning activity coupled with drier conditions is consistent with predictions under climate change scenarios.
However; it may not necessarily be detrimental because it could help introduce genetic resources that assists a species to adapt to climate change.
Climate change Some trends indicating changes to key climate measures have been observed for Tasmania since the mid 20th century (Corney et al.; 2010 Steffen and Hughes; 2013 Grose et al.; 2015).
Climate modelling forecasts a rise in temperature for Tasmania of between 1.6oC (low emissions) to 2.9oC (high emissions) over the next century to 2100; depending on emissions scenario (Corney et al.; 2010).
The observed and predicted changes are partly driven by shifts in the large scale climate drivers that influence Australia.
Any likely impacts due to climate change will be additional to existing stressors already facing the native plants and animals of Tasmania; notably the landscape modification and fragmentation of native vegetation across the north and east of the State.
The changes in climate are also likely to foster the establishment and spread of undesirable pests and diseases that currently are not suited for the Tasmanian climate (Steffen and Hughes; 2013).
The observed climatic trends from the late 20th century plus the available climatic modelling indicate that the black gum Brookers gum forest woodland ecological community is likely to be impacted by future climate change.
However; a consequence of climate change is the likelihood of more severe weather events (storms; droughts); (as happened in 2016).
Often considered as altered fire frequency but also from changes to fire intensity and season; such as occurs during prescribed burning.
Infestations also increase erosion and silting; reduce water availability; alter nutrient cycles; damage the quality of habitats for native fauna (e.g. shading by willows reduces light and temperature for aquatic fauna resident in streams and ponds) and may increase the risk of fire hazard through their dense; rampant growth.
Fire increased the richness of exotic species; especially for sites burnt in spring or at more frequent intervals of under seven years.
The nature and impacts of fire can be influenced by other threats in the landscape.
Conversely; circumstances that promote fire occasionally occur; notably; invasion by weeds that increase fuel load; allowing fire to spread more quickly through a patch or into the tree canopy.
Too frequent fires may eliminate sensitive species; for example obligate seeder species that require fire to stimulate seed germination may die out if recurring fires kill plants before they have a chance to mature and develop new seeds.
Conversely; a lack of fire or extended intervals between fire events may limit recruitment of plant species; especially those that require heat; smoke or other feature of a fire to stimulate germination and establishment of seedlings.
Changes to fire frequency also impacts on fauna by affecting habitat diversity.
For instance; depending on the nature of the changed fire regime; there may be reduced opportunities for tree hollows and logs; or regeneration of dense thickets of trees and shrubs may be prevented; providing less shelter and food resources to many kinds of fauna.
The result was significant damage to natural vegetation; particularly highly fire sensitive vegetation in the World Heritage Area that may take decades to recover (Bowman; 2016).
The ratings indicate the component of the ecological community most sensitive to fire is the E. brookeriana wet forest; rated as highly fire sensitive and moderately flammable (Table C4).
These adjacent wet forest types are poorly adapted to fire; being rated as highly to very highly (for Nothofagus rainforest) fire sensitive (Pyrke and Marsden Smedley; 2005).
A single fire has capacity to effect significant change to wet ecological communities.
The extensive fires in the east and south east are most likely to concern the least sensitive dry sclerophyll black gum forests that are able to recover from single fire events or fires spaced over intervals measured in years rather than decades.
TASVEG vegetation unit Fire Attributes Category Fire Sensitivity Flammability Key units Eucalyptus brookeriana wet forest Wet sclerophyll forest High Moderate (WBR) Eucalyptus ovata forest and Dry sclerophyll forest Low High woodland (DOV) Eucalyptus ovata heathy woodland Dry sclerophyll woodland Low High (DOW) Associated mosaic units Eucalyptus globulus King Island Mixed forest Moderate Moderate forest (WGK) King Island eucalypt woodland Damp sclerophyll forest Moderate Moderate (DKW) Midlands woodland complex Dry sclerophyll woodland Low High (DMW) Source Pyrke and Marsden Smedley (2005) updated by Tasmanian Planning Commission (2009).
A single fire will generally not affect biodiversity although repeated short intervals (i.e. 10 years) may cause long term changes.
Given the ecological community is associated with moist and poorly draining sites; the potentially hotter and drier summers along with likely harsher extreme and fire weather events; could impose limits to suitable habitat and capacity for regeneration of the ecological community within the coming century.
The impacts from bushfire or drought would most likely be regional; rather than affect the entire range of the ecological community.
Eligible under Criterion 4 for listing as Endangered Evidence The Black gum Brookers gum forest woodland ecological community has experienced an approximate 90 loss of extent and an associated reduction in community integrity that is most apparent through the impacts of fragmentation of the ecological community; loss of the old growth forest component; changes to vegetation structure and altered species composition (in terms of loss of native species and their replacement by weeds and feral animals); and fire impacts.
There appears to be relatively less impact of fires in north western Tasmania; where the fire sensitive Brookers gum wet forest component mostly occurs.
Overall; about 7 of the total extent of fire sensitive units were burnt since 2000 01 (compared to about 12 of the total extent of low sensitivity dry forest units being burnt over the same period).
Fire sensitive units accounted for about a quarter of the total extent of the ecological community burnt since 2000. 4.
Such events could make the fire sensitive wet forest components more susceptible to fires; noting their recovery is likely to take decades to centuries post fire.
A considerable proportion of the ecological community has been impacted by fire events within the past 30 years.
In light of persistent weed invasion; the impacts of recent fires; particularly to more fire sensitive components of the ecological community; plus the potential for increased fire events; it is likely restoration of the ecological community can take a long time.
As well as disrupting natural water flows; there are also changes to water quality; for instance acidification or contamination with toxins or excessive nutrients of the water supply.
Given the ecological community is associated with moist and poorly draining sites; the potentially hotter and drier summers along with likely harsher extreme and fire weather events; could impose limits to suitable habitat and capacity for regeneration of the ecological community within the coming century.
There remains a possibility of catastrophic impacts due to bushfires; drought or ongoing clearance (see Criterion 5; below).
The impacts from bushfire or drought would most likely be regional; rather than affect the entire range of the ecological community.