Cooks River Clay Plain Scrub Forest

Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the List of Ecological Communities under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Generally accepted name

A nomination was received for Cooks River Clay Plain Scrub Forest.

The TSSC considers that the nominated ecological community, Cooks River Clay Plain Scrub Forest, is a component of a broader ecological community, and that the broader ecological community should be assessed for listing under the EPBC Act.

2. International/National Context

The nomination refers to vegetation types that occur predominantly along the Cooks River and parts of the catchments of Parramatta and Georges Rivers, within the Sydney Basin Bioregion, NSW.

Recent work by the NSW National Parks and Wildlife Service has identified Cooks River Clay Plain Scrub Forest as being an identified sub-community within the Castlereagh Ironbark Forest. There are likely to be other ecological communities similar to this broader community within the Sydney Basin Bioregion, the South East Corner Bioregion of NSW, or in Victoria.

3. Description

Cooks River Clay Plain Scrub Forest is dominated by Eucalyptus fibrosa (Broad-leaved Ironbark), with E. longifolia (Woollybutt) also present on slow draining sites and E. moluccana (Grey Box) on sites with better drainage. Other tree species that may form part of the canopy include E. resinifera (Red Mahogany), and in moist sheltered positions, Syncarpia glomulifera (Turpentine). The understorey is usually floristically diverse, but is dominated by paperbarks, particularly Melaleuca decora and M. nodosa. Common smaller shrubs include Pultenaea villosa, Acacia falcata and Leptospermum trinervium.

Cooks River Clay Plain Scrub Forest occurs on soils derived from Wianamatta shale, often with a high component of ironstone nodules.

This ecological community was once prevalent in the Bankstown-Auburn-Regents Park and Strathfield districts, but has been severely impacted upon by the development of inner South-western Sydney, and the spread of industrial and urban infrastructure. The nomination states that remaining patches of this vegetation type (totalling approximately 30 ha) occur in only a small number of disjunct sties, and are fragmented, suffer from weed degradation, rubbish dumping, or neglect. Other identified threats include water pollution, unauthorised access, and destructive and inappropriate development.

4. How judged by TSSC in relation to the Environment Protection and Biodiversity Conservation Act 1999 criteria.

The TSSC was unable to assess the nomination against the criteria as insufficient information was provided about its national extent.

Criterion 1 - Decline in geographic distribution

Information was provided about the decline in geographic distribution for one ecological community, Cooks River Clay Plain Scrub Forest. No information about the national extent of this community was provided. The TSSC was therefore unable to determine the overall decline in geographic distribution of the ecological community and hence the eligibility of the ecological community against this criterion.

Criterion 2 - Small geographic distribution coupled with demonstrable threat

The ecological community nominated has a small geographic distribution and occurs as fragmented patches. However, information about the national extent of this community was not provided.

Due to a lack of comprehensive information on the national extent of the ecological community, the TSSC was unable to assess the eligibility of the ecological community under this criterion.

Criterion 3 - Loss or decline of functionally important species

Research conducted by the by NSW National Parks and Wildlife Service suggested that some remnants have had the floristic composition altered by selective removal of canopy species. However, the eventual impact this has on the ongoing survival of the ecological community is not outlined. Therefore, the TSSC was unable to assess the eligibility of the ecological community under this criterion.

Criterion 4 - Reduction in community integrity

The nomination provides no information under this criterion.

Criterion 5 - Rate of continuing detrimental change

The nomination provides no information under this criterion.

Criterion 6 - Quantitative analysis showing probability of extinction

The nomination provides no information under this criterion.

5. Conclusion

An extensive survey and mapping project was conducted by NSW National Parks and Wildlife Service in the Cumberland Plain. The results of this survey indicate that the Cooks River Clay Plain Scrub Forest is part of a larger ecological community, namely the Castlereagh Ironbark Forest. However, Environment Australia's research indicates that even this broader ecological community may be only a single representative of a more widely occurring community, for example 'temperate Eucalyptus fibrosa/Melaleuca decora woodland'. As such, Cooks River Clay Plain Scrub Forest should be assessed as part of the broader ecological community.

6. Recommendation

The TSSC recommends that the nomination for:

  • Cooks River Clay Plain Scrub Forest

be rejected due to the lack of sufficient information about the ecological community's national extent and threatened status, and that this ecological community be considered and assessed as a component of a broader ecological community.

The TSSC will identify and consider an appropriate broader ecological community as part of the process of assessing State and Territory lists of ecological communities.