Robertson Basalt Tall Open-forest in the Sydney Basin Bioregion - Determination to make a minor amendment to Part 3 of Schedule 1 of the Threatened Species Conservation Act

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Determination to make a minor amendment to Part 3 of Schedule 1 (Endangered ecological communities) of the Act by inserting the Robertson Basalt Tall Open-forest in the Sydney Basin Bioregion (as described in the determination of the Scientific Committee under Division 5 Part 2) and as a consequence to omit reference to the Robertson Basalt Tall Open-forest in the Sydney Basin Bioregion (as described in the final determination to list the ecological community) which was published on pages 3697 to 3701 in the NSW Government Gazette No. 97 dated 15 June 2001. Minor amendments to the Schedules are provided for by Division 5 of Part 2 of the Act.

The Scientific Committee is of the opinion that the amendment is necessary or desirable to correct minor errors or omissions in the Determination in relation to the Thackway and Cresswell (1995) reference.

NSW Scientific Committee – final determination

The Scientific Committee has found that:

1. Robertson Basalt Tall Open-forest in the Sydney Basin Bioregion is the name given to the ecological community characterised by the species assemblage listed in 2 below. The community occurs on high nutrient soils in high rainfall areas of the Southern Highlands. All sites are within the Sydney Basin Bioregion. Bioregions are defined in Thackway and Cresswell (1995).

2. Robertson Basalt Tall Open-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 vertebrates and invertebrates, many of which are poorly known. Invertebrate species may be restricted to soils or canopy trees and shrubs. In any particular site not all of the assemblage listed above may be present. At any one time, seeds of some species may only be present 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 Robertson Basalt Tall Open-forest was predominantly of tall open-forest structure, though remnants may now be of open forest or woodland structure due to clearing and disturbance. Typical trees include Eucalyptus fastigata,  Eucalyptus viminalis, Eucalyptus elata and  Eucalyptus radiata.

5 Robertson Basalt Tall Open-forest is found on high fertility soils derived generally from Tertiary basalts (mainly the Robertson Basalt and Kangaroo Valley Basanite), on areas of high rainfall (1000-1600 mm per annum). It is referred to in Fisher, Ryan & Lembit (1995) and Kodela (1990).

6 Robertson Basalt Tall Open-forest is or has been known to occur in the Wingecarribee and Shoalhaven Local Government areas, but may occur elsewhere in the Sydney Basin Bioregion (sensu Thackway and Cresswell 1995). It has been reported from the Southern Highlands on the Robertson plateau and Cambewarra Range (Kodela, 1990, Kevin Mills pers. comm.).

7 Disturbed Robertson Basalt Tall Open-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.

8 Robertson Basalt Tall Open-forest has been extensively cleared for agriculture and rural development. About 400ha or less than 15% of its original occurrence has been estimated to remain though this is mostly as small and isolated pockets.

9 Robertson Basalt Tall Open-forest has not been reported from any NPWS national parks or nature reserves.

10 Much of the remaining area of Robertson Basalt Tall Open-forest is highly fragmented with much of it occurring on private land. Threatening processes include clearing, logging, burning, introduced species and grazing.

11 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 Robertson Basalt Tall Open-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.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 14/10/11
Exhibition period: 14/10/11 - 9/12/11

Note this ecological community was originally listed in 2001 as indicated in the determination

References

Fisher, M., Ryan, K. & Lembit, R. (1995) The natural vegetation of the Burragorang 1:100 000 map sheet. Cunninghamia 4(2): 143-215.

Kodela, P.G. (1990) Modern pollen rain from forest communities. Australian Journal of Botany 38:1-24.

Thackway R, Cresswell ID (1995) An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserves System Cooperative Program. (Version 4.0. Australian Nature Conservation Agency: Canberra.)