Shale Sandstone Transition Forest of the Sydney Basin Bioregion

Status: Critically Endangered on the EPBC Act list

Shale Sandstone Transition Forest occurs only in New South Wales, within the Sydney Basin Bioregion. As the name implies, this ecological community occurs between other ecological communities found respectively on shale or sandstone substrates. It is found to the west of Sydney, on the edges of the Cumberland Plain, (particularly the southern edge), as well as on the sandstone-dominated Hornsby, Woronora, and Lower Blue Mountains plateaux that adjoin the plain.

Government evidence of impact of climate change:

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  • Approved Conservation Advice (including listing advice) for Shale Sandstone Transition Forest of the Sydney Basin Bioregion (EC25R)

    Lat) (NSW TSC Act) Infection of native plants by Phytophthora cinnamomi (NSW TSC Act) Dieback caused by the root rot fungus (Phytophthora cinnamomi) (EPBC Act) Introduction and establishment of Exotic Rust Fungi of the order Pucciniales pathogenic on plants of the family Myrtaceae (NSW TSC Act) Competition and land degradation by rabbits (EPBC Act) Competition and grazing by the feral European Rabbit; Oryctolagus cuniculus (NSW TSC Act) Loss of hollow bearing trees (NSW TSC Act) Removal of dead wood and dead trees (NSW TSC Act) Competition from feral honeybees (NSW TSC Act) Aggressive exclusion of birds from woodland and forest habitat by abundant Noisy Miners Manorina melanocephala (NSW TSC Act) Predation by European red fox (EPBC Act) Predation by the European red fox (Vulpes vulpes) (NSW TSC Act) Predation by feral cats (EPBC Act) Predation by the feral cat (Felis catus) (NSW TSC Act) Loss of terrestrial climatic habitat caused by anthropogenic emissions of greenhouse gases (EPBC Act) Anthropogenic climate change (NSW TSC Act) High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition (NSW TSC Act).

    Climate change is likely to increase the severity of many existing threats; as well as adding new stress to the ecological community.

    Climate Change Climate change is now understood to pose a serious long term threat to terrestrial and aquatic ecosystems and to have the potential to change the ecology of these environments; through changed species composition and function (Dunlop et al.; 2012).

    In summary; these include Continued clearing; degradation; and fragmentation will limit the ability of the ecological community to adapt and or migrate in response to climate change Grazing pressure and associated detrimental effects such as depletion of the indigenous understorey; and ringbarking of some tree species (especially stringybarks and woollybutt) may increase under forecast climate change Invasion by non native plant species is likely to increase in intensity; spread; and diversity; with some such species taking advantage of climate change induced effects such as periodic depletion of ground cover due to drought and over grazing.

    Weeds such as African olive and lantana (Lantana camara) are likely to move into areas where they are currently excluded by relatively cold temperatures Remnants containing riparian vegetation may suffer erosion due to intensification of rainfall events; and this increased disturbance may facilitate or worsen weed invasion Altered native plant species mix Altered structural composition of remnants may include an increase in shrub cover; a decrease in grass cover; and variable changes to tree cover Altered structure and or floristics may change fauna composition in and between remnants; and may alter the behaviour of migratory species; including some that perform significant ecosystem functions Increased risk of ecological instability through asynchrony of events such as emergence of insect prey and arrival of migratory bird predators and Altered fire regimes due to changed climate and weather; and due to changed vegetation structure and composition.

    While the ecological community is likely to be vulnerable to the impacts of climate change; at a regional level it may still play an important role in supporting ecological adaptation.

    With other woodlands and forests on the coastal slopes of the Great Dividing Range it may provide refuge for threatened lowland specialists such as regent honeyeaters and swift parrots in an increasingly dry climate further inland.

    This process operates separately to any temperature rise due to global climate change.

    Climate change is expected to cause increasing damage to the ecological community; through changed temperature and rainfall patterns.

    Other influences on the frequency and intensity of fire in the ecological community include suppression for asset protection; change in floristic composition (for example; with the introduction of weeds such as African olive) and climate change.

    Reduction in integrity through climate change As described in Description of Threats; climate change is likely to compromise the integrity of the community both directly and by altering the survival rates of constituent species.

    These losses are compounded by climate change; and together with a range of ecological characteristics of the community; as well as the nature of the ongoing threats severely limit the likelihood of recovery.

    Benson and Howell (2002) describe the rapidity with which the structure of understorey layers of woodlands on the Cumberland Plain can change in response to influences such as rainfall; fire or grazing.

    The key threats that have had a major impact in the past and or are affecting the ecological community now are vegetation clearing and fragmentation; particularly for urban development invasion by exotic species inappropriate grazing regimes (and mowing) inappropriate fire regimes inappropriate recreational use rubbish dumping (as a source of weeds and pollutants) removal of wood soil salinisation. 2.1 Key Threatening Processes Key threatening processes identified under the NSW TSC Act and EPBC Act that are affecting Shale Sandstone Transition Forest are Land clearance (EPBC Act) Clearing of native vegetation (NSW TSC Act) Loss and degradation of native plant and animal habitat by invasion of escaped garden plants; including aquatic plants (NSW TSC Act EPBC Act) Invasion of native plant communities by exotic perennial grasses (NSW TSC Act) Invasion of native plant communities by African olive (NSW TSC Act) Invasion and establishment of exotic vines and scramblers (NSW TSC Act) Invasion; establishment and spread of Lantana (Lantana camara L. sens.

    The ecological community is subject to a range of ongoing threats including clearing; fragmentation and other damage associated with urbanisation loss of ecological services associated with populations of fauna that have been lost or reduced and inappropriate fire regimes.

    Bursaria has often been removed from the ecological community for pasture improvement or by a change in fire regime; resulting in the likelihood that Christmas beetle populations will boom more often; with possible effects on the canopy trees (sensu Ridsdill Smith; 1970 Davidson Davidson; 1992).

    The number of species; and the above ground relative abundance of species will change with time since fire; and may also change in response to changes in fire regime (including changes in fire frequency) (NSW Scientific Committee; 2012).

    T. australis declines in the absence of fire and Bursaria spinosa is found in high abundance in low fire frequency sites to the point where the species can dominate much of the landscape (Watson and Morris; 2006).

    Leary (2007) also comments on the substantial reduction and modification of ground cover; due to the alteration of fire regimes.

    Altered fire regimes Shale Sandstone Transition Forest occurs in and near urban and peri urban areas.

    Key threats include the impacts associated with clearance and fragmentation of remnants as well as weed invasion and change in fire regimes.

    In addition to direct stress on plants and animals; this is likely to result in changed habitat features and food availability; as well as being expected to compound other threats such as inappropriate fire regimes.

    Reduction in integrity through inappropriate fire and grazing regimes The ground layer of the ecological community is often extensively modified by grazing and mowing contributing to the loss of grazing sensitive palatable species and those that are intolerant of relatively frequent and or intensive mowing (Douglas and James; pers. comms.; 2011).

    It is also likely to interact with other threats; such as changed fire regimes or the invasion of weeds.

    Nonetheless; the likely change in temperature and precipitation; as well as influences on the fire regime and the competitive relationships between species limit the likelihood of the ecological community recovering its former nature.

    Summary Substantial clearing; severe fragmentation; urbanisation; weed invasion; inappropriate fire and grazing regimes; and associated changes to vegetation structure and loss of faunal components have substantially reduced the integrity of the ecological community.

    In addition; inappropriate fire and grazing regimes that alter the species composition of the vegetation in the ecological community and urban and peri urban development continue to be detrimental to the ecological community.