Shale gravel transition forest in the Sydney Basin Bioregion - endangered ecological community listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list Shale Gravel Transition Forest in the Sydney Basin Bioregion, as an ENDANGERED ECOLOGICAL COMMUNITY on Part 3 of Schedule 1 of the Act. Listing of Endangered Ecological Communities is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Shale Gravel Transition Forest in the Sydney Basin Bioregion is the name given to the ecological community characterised by the species assemblage listed in paragraph 2. All sites are within the Sydney Basin Bioregion.

2. Shale Gravel Transition Forest is characterised by the following assemblage:

3. The total species list of the flora and fauna of the community is considerably larger than that given in 2 (above), with many species present in only one or two sites or in very small quantity. The community includes invertebrates many of which are poorly known, as well as vertebrates. In any particular site not all of the assemblage listed above may be present. At any one time, some species may only be present as seeds in the soil seed bank with no above-ground individuals present. Invertebrate species may be restricted to soils or canopy trees and shrubs, for example. The species composition of the site will be influenced by the size of the site and by its recent disturbance history. The number of species and the above-ground composition of species will change with time since fire, and may also change in response to changes in fire frequency.

4. Shale Gravel Transition Forest is predominantly of open-forest structure, usually with trees of Eucalyptus fibrosa sometimes with  E. moluccana and  Eucalyptus tereticornis.  Melaleuca decora is frequently present in a small tree stratum. A sparse shrub stratum is usually present with species such as  Bursaria spinosa,  Daviesia ulicifolia and  Lissanthe strigosa. Ground-layer species include  Microlaena stipoides subsp.  stipoides,  Cheilanthes sieberi subsp.  sieberi,  Themeda australis,  Opercularia diphylla,  Lomandra multiflora subsp.  multiflora,  Aristida vagans,  Pratia purpurascens and  Wahlenbergia gracilis.

5. Shale Gravel Transition Forest occurs primarily in areas where shallow deposits of Tertiary alluvium overlie shale soils but may also occur in association with localised concentrations of iron-indurated gravel. Shale Gravel Transition Forest grades into Cumberland Plain Woodland as alluvial and ironstone influences decline. On thicker deposits of Tertiary alluvium it grades into Cooks River/Castlereagh Ironbark Forest or Castlereagh Scribbly Gum Woodland. South of the Tertiary alluvial deposits at Holsworthy, this community forms complex mosaics with shale/sandstone transitional communities.

6. Shale Gravel Transition Forest is described in NSW NPWS (2000a&b) which lists diagnostic plant species for the community. These species provide a guide to identification of the community, but care should be taken in the application and interpretation of diagnostic plant species because of sampling limitations; the reduction in species diversity in degraded sites; and the fact that some species may only be present at a site at some times as a soil seedbank or as dormant bud/tubers.

7. Shale Gravel Transition Forest is or has been known to occur in the Auburn, Bankstown, Baulkham Hills, Blacktown, Fairfield, Hawkesbury, Holroyd, Liverpool, Parramatta and Penrith Local Government Areas, but may occur elsewhere in the Sydney Basin Bioregion.

8. Disturbed Shale Gravel Transition Forest remnants are considered to form part of the community including where the vegetation would respond to assisted natural regeneration, such as where the natural soil and associated seedbank is still at least partially intact.

9. Shale Gravel Transition Forest has been cleared for agriculture and rural development. About 36% of the original distribution of about 7000 ha remains (NSW NPWS 2000a) and much of this is in a degraded state.

10. Shale Gravel Transition Forest occurs in Agnes Banks Nature Reserve, Castlereagh Nature Reserve, Scheyville National Park and Windsor Downs Nature Reserve. The area in these reserves is about 3% of the original distribution.

11. Much of the remaining area of Shale Gravel Transition Forest has been disturbed by clearing, tracks, weeds invasion and soil disturbance. Continuing threats include invasion of exotic species, illegal dumping, unauthorised access, fragmentation and clearing for urban, rural residential recreational and industrial development.

12. In view of the originally restricted distribution of this community, its inadequate representation within conservation reserves, the extensive disturbance and weed invasion that has occurred, and the threats from ongoing development, the Scientific Committee is of the opinion that Shale Gravel Transition Forest in the Sydney Basin Bioregion is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate and that the community is eligible for listing as an endangered ecological community.

Proposed Gazettal date: 19/04/02
Exhibition period: 19/04/02 - 24/05/02

References

NSW NPWS (2000a). Native vegetation maps of the Cumberland Plain, Western Sydney - Interpretation guidelines. NSW National Parks & Wildlife Service, 2000.

NSW NPSW (2000b). The native vegetation of the Cumberland Plain, Western Sydney - Technical report. NSW National Parks & Wildlife Service, 2000.