Mount Gibraltar 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 Mount Gibraltar 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 Mount Gibraltar Forest in the Sydney Basin Bioregion (as described in the final determination to list the ecological community) which was published on pages 1272 to 1276 in the NSW Government Gazette No. 54 dated 16 March 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. Mount Gibraltar Forest in the Sydney Basin Bioregion is the name given to the plant community characterised by the species assemblage listed in 2 below. All sites are within the Sydney Basin Bioregion. Bioregions are defined in Thackway and Cresswell (1995). The community is described in Fisher, Ryan & Lembit (1995).

2. Mount Gibraltar 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, seeds of some plant 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 Mount Gibraltar Forest includes vegetation ranging from open-forest to woodland and scrub depending on aspect, soil conditions and previous clearing and disturbance. Typical trees include Eucalyptus radiata, Eucalyptus piperita and  Eucalyptus smithii, on the upper slopes, and  Eucalyptus radiata, Eucalyptus piperita, Eucalyptus fastigata and  Eucalyptus viminalis on the deeper soils on the southern side.

5 Understorey species in the open-forest are predominantly herbaceous and grassy and include Stypandra glauca, Dianella caerulea, Dichondra repens, Themeda australis, Blechnum cartilagineum, Adiantum aethiopicum, Tylophora barbata, Oreomyrrhis eriopoda, Cymbopogon refractus, Senecio linearis, Polyscias sambucifolia, Exocarpos cupressiformis, Leucopogon lanceolatus and  Lomandra longifolia. The tall forest is dominated by ferns such as  Blechnum cartilagineum, Doodia aspera, Pteridium esculentum, and twiners such as  Eustrephus latifolius and  Tylophora barbata. There may be small patches of rainforest species such as  Acacia melanoxylon, Hedycarya angustifolia, Notelaea venosa, Pittosporum undulatum and  Cyathea australis. Scrub with  Melaleuca hypericifolia, Leptospermum brevipes and  Leptospermum polygalifolium may occur on exfoliating rock on exposed sites.

6 Mount Gibraltar Forest is found on clay soils derived from a microsyenite volcanic intrusion associated with Mount Gibraltar near Bowral, but may also have occurred on nearby mountains such as Mount Jellore, Mount Flora, Mount Misery and Cockatoo Hill depending on the extent of microsyenite. It is referred to in Fisher, Ryan & Lembit (1995)

7 Mount Gibraltar Forest is or has been known to occur in the Wingecarribee Local Government Area, but may occur elsewhere in the Sydney Basin Bioregion. Bioregions are defined in Thackway and Cresswell (1995).

8 Disturbed Mount Gibraltar 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 Mount Gibraltar Forest has been cleared for agriculture and rural development. Remnants are mostly small isolated pockets.

10 Mount Gibraltar Forest has not been reported from any NPWS reserves.

11 Much of the remaining area of Mount Gibraltar Forest is largely isolated from other areas of bushland. Ongoing threats to the remnants include exotic weed invasion such as Hedera, Lonicera, Ilex, Berberis, Pyracantha and  Genista, pressure from adjacent urban development (including dogs, cats, rubbish dumping, noise, trampling and vehicles), inappropriate fire regimes and disturbances associated with communication tower infrastructure (including clearing, movement of machinery, weed introduction, dumping of rubbish).

12 In view of the restricted distribution of this community, the ongoing threats to the remnants and its inadequate representation within conservation reserves, the Scientific Committee is of the opinion that Mount Gibraltar 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.

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.)