The Cooks River/Castlereagh Ironbark Forest of the Sydney Basin Bioregion is a dry sclerophyll open-forest to low woodland which occurs predominantly in the Cumberland Subregion between Castlereagh and Holsworthy, as well as around the headwaters of the Cooks River
Cooks River/Castlereagh Ironbark Forest of the Sydney Basin Bioregion
Status: Critically Endangered on the EPBC Act list
Government evidence of impact of climate change:
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Approved Conservation Advice (including listing advice) for Cooks River/Castlereagh Ironbark Forest of the Sydney Basin Bioregion
Climate change Other threats related to increased urbanisation.
Other ongoing threats include Climate change.
Climate change is likely to increase the severity of many existing threats.
Climate change Climate change poses 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).
Not only does climate change directly threaten species that cannot adapt; it is also likely to exacerbate existing threats; including loss of habitat; altered hydrological regimes; altered fire regimes and invasive species.
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 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 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 flora and fauna species mix and Altered fire regimes due to changed climate and weather; and due to changed vegetation structure and composition.
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.
In addition to clearance and fragmentation of native vegetation; key threats to the ecological community occurring as a result of increasing urbanisation are Inappropriate fire regimes; most significantly increased fire frequency due to arson; although some patches have been impacted by a lack of burns.
The ecological community is subject to a range of ongoing threats including clearing; fragmentation and other damage associated with urbanisation inappropriate fire regimes; weed invasion; nutrient loading and changes to hydrology (NSW DECCW; 2010).
Criterion 4 Reduction in community integrity The ecological community has undergone a very severe reduction in its ecological integrity through fragmentation structural alteration to the mid and ground layers as a result of altered fire regimes and to the canopy as a result of clearance; urbanisation; weed invasion; inappropriate fire and grazing regimes and decline in faunal components.
The Best Practice Guidelines Cooks River Castlereagh Ironbark Forest contains further information on appropriate and inappropriate fire regimes; recommended frequency; site preparation and post fire maintenance and monitoring.
The main threats are vegetation clearance due to agriculture and; more recently; urban and industrial expansion inappropriate fire regimes and weed invasion.
Altered fire regimes The vegetation composition of Cooks River Castlereagh Ironbark Forest is influenced by its recent disturbance history; as well as the patch size (NSW Scientific Committee; 2011).
High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition is a Key Threatening Process under the NSW Threatened Species Conservation Act 1995 (NSW OEH; 2014a).
Conversely; the exclusion of fire for greater than 30 years is likely to have a detrimental impact on the ecological community; particularly through the loss of understorey plant diversity (DECC; 2005).
Invasion by weeds Alteration of the natural fire regime (fewer fires) leads to the accumulation of leaf litter.
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 loss through clearance of vegetation; threats associated with urbanisation including weed invasion; inappropriate fire regimes; changes to hydrology; dumping and predation by domestic pets are expected to increase as western Sydney is further developed.
Reduction in integrity through inappropriate fire regimes Another impact of increasing urbanisation is arson.
It is also likely to interact with other threats; such as changed fire regimes or the invasion of weeds.
Summary Substantial clearing; severe fragmentation; urbanisation; weed invasion; inappropriate fire regimes; and associated changes to vegetation structure and loss of faunal components have substantially reduced the integrity of the ecological community across its range.
The increasing urbanisation of western Sydney will increase the rate of detrimental change through increased run off and nutrient loads further changes to fire regimes predation by introduced species and other impacts.
High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition profile.