Duffys Forest ecological community in the Sydney Basin Bioregion - endangered ecological community listing

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. A Notice of Final Determination to list the Duffys Forest vegetation community appeared in the NSW Government Gazette No. 112 on 24th July, 1998. The Scientific Committee considers that an amendment should be made to this listing following the receipt of additional information about the ecological community.

2. Duffys Forest Ecological Community is the accepted name for the ecological community that occurs on the ridgetops, plateaus, upper slopes and occasionally mid slopes on Hawkesbury sandstone geology, typically in association with laterite soils and soils derived from shale and laminite lenses. It has the structural form predominantly of open-forest to woodland. The Duffys Forest Ecological Community has been reported from the Warringah, Pittwater, Ku-ring-gai, Hornsby and Manly Local Government Areas, although it may occur elsewhere in the Sydney Basin Bioregion.

3. Duffys Forest Ecological Community is characterised by the following assemblage of vascular plant species:

4. The total species list of the community is considerably larger than that given in 3 (above), with many species present in only one or two sites or in very small quantity. In any particular site not all of the assemblage listed in 3 may be present. At any one time, seeds of some species may only be present in the soil seedbank with no above ground individuals present. 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. The community is an important habitat for a diverse fauna (vertebrates and invertebrates), but detailed records are not available from most stands and the invertebrate fauna is poorly known.

5. Smith & Smith (2000) give a list of diagnostic plant species for Duffys Forest Ecological Community and describe how the community can be distinguished from surrounding ecological communities. Diagnostic 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 part of the soil seedbank or as dormant buds/tubers.

6. The endangered shrub Grevillea caleyi is largely restricted to Duffys Forest Ecological Community though it is not present at all locations of the community. Other threatened plant species known from the community include Persoonia hirsuta, Tetratheca glandulosa, Pimelea curviflora var. curviflora, Epacris purpurascens var. purpurascens.

7. The Scientific Committee noted that general information on the Duffys Forest Ecological Community is contained in:

Benson, D. & Howell, J. (1994) The natural vegetation of the Sydney 1:100 000 map sheet. Cunninghamia 3(4) 677-787.

NPWS (2001) Grevillea caleyi R.Br. (Proteaceae) Draft Recovery Plan for public comment. NSW National Parks and Wildlife Service, Hurstville.

Thomas, J. & Benson, D.H. (1985) Vegetation survey of Ku-ring-gai Chase National Park. National Herbarium of New South Wales, Royal Botanic Gardens, Sydney.

Sheringham, P.R. & Sanders, J.M. (1993) Vegetation survey of Garigal National Park and surrounding Crown Lands. A report for the NSW National Parks and Wildlife Service.

Scott, J., Marshall, A. & Auld, T.D.(1995) Conservation research statement and recovery plan for Grevillea caleyi. ANCA Endangered Species Project No. 456.

Smith, P. & Smith, J. (2000) Survey of the Duffys Forest Vegetation Community. Unpublished Report to NSW National Parks and Wildlife Service and Warringah Council.

These surveys and accompanying maps are by no means inclusive in their representation of Duffys Forest Ecological Community. The scale of the Sydney map is too coarse to map the smaller remnants of this community. The community is highly fragmented by urban developments and not all the small fragments appear on the maps. Duffys Forest Ecological Community is represented on the southern edge of the Ku-ring-gai Chase National Park vegetation map (Thomas & Benson 1985) and the northern edge of the Garigal National Park vegetation map (Sheringham & Sanders 1993). These two maps do not directly abut as there is a gap in the middle comprising cleared land within which small remnant patches of the Duffys Forest Ecological Community exist. Some disturbed or degraded remnants of Duffys Forest Ecological Community may not be mapped as the community in Smith and Smith (2000).

8. It is estimated that only 15% of the original area of the Duffys Forest Ecological Community currently exists in the form of a number of remnants.

9. Threats to the survival of the Duffys Forest Ecological Community include land clearing and associated fragmentation, habitat degradation by rubbish dumping; weed invasion facilitated by urban runoff, an inappropriate fire regime, unauthorised horse riding activities in the area and access by people, trail bikes, and other vehicles.

10. Only a small number of fragments of the Duffys Forest Ecological Community occur within Ku-ring-gai Chase and Garigal National Parks, and all of these are on the boundary of the Parks and bounded by roads.

11. In view of the substantial reduction in the area occupied by the community, its fragmentation and the numerous threats to the community, the Scientific Committee is of the opinion that Duffys Forest Ecological Community is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival cease to operate and that listing as an endangered ecological community is warranted.