Hunter Valley Weeping Myall Woodland of 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 Hunter Valley Weeping Myall Woodland of 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 Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion (as described in the final determination to list the ecological community) which was published on pages 9754 to 9756 in the NSW Government Gazette No. 142 dated 25 November 2005. 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.

This determination has been superseded by the 2016 Determination (Critically endangered ecological community listing).

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion is the name given to the ecological community associated with heavy clay soils on depositional landforms in the south-western part of the Hunter River valley floor. Mean annual rainfall within the current known range of the ecological community varies from about 550 to 650mm. Hunter Valley Weeping Myall Woodland is characterised by the assemblage of species listed in paragraph 2 and typically comprises a relatively dense or open tree canopy up to about 15m tall, sometimes with an open understorey of semi-sclerophyllous shrubs, and a variable groundcover dominated by grasses or herbs. In disturbed stands the canopy may consist of either scattered trees or dense regrowth and the understorey may comprise relatively few native species above ground.

2. The Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion is characterised by following assemblage of species:

3. The total species list of the community is larger than that given above, with many species present only in one or two sites, or in low abundance. The species composition of a site will be influenced by the size of the site, recent rainfall or drought conditions and by its disturbance (including grazing, flooding, land clearing and fire) history. The number and relative abundance of species will change with time since fire, and may also change in response to changes in fire frequency or grazing regime. At any one time, above-ground individuals of some species may be absent, but the species may be represented below ground in the soil seed banks or as dormant structures such as bulbs, corms, rhizomes, rootstocks or lignotubers. The list of species given above is of vascular plants, however the community also includes micro-organisms, fungi, cryptogamic plants and both vertebrate and invertebrate fauna. These components of the community are poorly documented.

4. Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion typically has a dense to open tree canopy up to about 15 m tall, depending on disturbance and regrowth history (Peake 2005). The most common tree is Acacia pendula (Weeping Myall), which may occur with  Eucalyptus crebra (Narrow-leaved Ironbark),  A.salicina (Cooba) and/or trees within the  A. homalophylla – A. melvillei complex. Understorey shrubs may include  Canthium buxifolium (Stiff Canthium),  Dodonaea viscosa (Sticky Hopbush),  Geijera parviflora (Wilga),  Notelaea microphylla var.  microphylla (Native Olive) and  Senna zygophylla (Silver Cassia). However, the shrub stratum is absent from some stands. The groundcover varies from dense to sparse, and is comprised of grasses such as  Austrodanthonia fulva (a wallaby grass) and  Themeda australis (Kangaroo Grass), and low shrubs and herbs such as  Chrysocephalum apiculatum (Common Everlasting),  Einadia nutans subsp.  nutans (Climbing Saltbush),  Enchylaena tomentosa (Ruby Saltbush),  Maireana microphylla (Eastern Cotton Bush) and  Ptilotus semilanatus.

5. Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion is currently known from parts of the Muswellbrook and Singleton Local Government Areas, but may occur elsewhere in the bioregion. It may also occur in the Upper Hunter Local Government Area within the Brigalow Belt South bioregion, although its presence has not yet been confirmed there. Bioregions are defined in Thackway and Cresswell (1995).

6. Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion was described in Peake’s (2005) vegetation survey of the central Hunter valley. A number of vegetation surveys and mapping studies carried out in the surrounding regions have not detected the community. These include surveys of the Lower Hunter – Central Coast (NPWS 2000), Maitland Local Government Area (Hill 2003), Myanbat Military Area (Thomas 1998), and Yengo (Bell et al. 1993), Wollemi (Bell 1998) and Goulburn River national parks (Hill 2000). Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion is included within the ‘Western Vine Thickets’ vegetation class of Keith (2004). It also contains a number of species that are characteristic of the ‘Riverine Plain Woodlands’ vegetation class, including the dominant tree species,  Acacia pendula. However, Hunter Valley Weeping Myall Woodland occurs well outside the distribution of other communities that typify both of these classes of vegetation (Keith 2004).

7. Hunter Valley Weeping Myall Woodland is of conservation significance because it represents a disjunct coastal example of vegetation that is found principally on the western slopes of Great Dividing Range. Taxa such as Acacia pendula, A. homalopyhlla-A. melvillei complex,  Geijera parviflora, Enchylaena tomentosa, Maireana microphylla and  Ptilotus semilanatus are typical of the inland flora of southeastern Australia. The community also provides habitat for  Acacia pendula population in the Hunter catchment, listed as an Endangered Population on Schedule 1 of the  Threatened Species Conservation Act (1995).

8. Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion occurs within a region in which native vegetation has been extensively cleared and persists only as very small remnants of less than one-hectare or as isolated trees. It is threatened by small-scale vegetation clearing, fragmentation, small-scale disturbance to soils and groundcover, grazing and weed invasion. The total remaining area of Hunter Valley Weeping Myall Woodland is estimated to be less than ten hectares (Peake 2005). The community is likely to be at risk from stochastic events due to its small patch sizes and restricted range. Most examples of the community are grazed or affected by severe disturbance to the groundcover, and many of the constituent species exhibit poor recruitment (Peake 2005). In addition, invasion by pasture and roadside weeds and Asparagus asparagoides (Bridal Creeper) pose significant threats throughout the range of the community. Collectively, these processes indicate a continuing decline in the distribution and ecological function of the community. Clearing of native vegetation is listed as Key Threatening Processes under the  Threatened Species Conservation Act (1995).

9. Hunter Valley Weeping Myall Woodland in the Sydney Basin bioregion is not currently known to be represented within any conservation reserves.

10. In view of the above, the Scientific Committee is of the opinion that Hunter Valley Weeping Myall Woodland of the Sydney Basin bioregion is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival cease to operate.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 08/07/11
Exhibition period: 08/07/11 - 02/09/11

References

Bell SAJ (1998) ‘Wollemi National Park vegetation survey.’ Volumes 1 & 2. NSW National Parks and Wildlife Service, Hurstville.

Bell SAJ, Vollmer J, Gellie N (1993) ‘Yengo National Park and Parr State Recreation Area. Vegetation survey for use in fire management.’ NSW National Parks and Wildlife Service, Hurstville.

Hill L (2000) ‘Goulburn River National Park and Munghorn Gap Nature Reserve: vegetation survey for fire management purposes.’ NSW National Parks and Wildlife Service, Muswellbrook.

Hill L (2000) ‘The natural vegetation of the Maitland Local Government Area.’ Maitland City Council, Maitland.

Keith DA (2004) ‘Ocean shores to desert dunes: the native vegetation of New South Wales and the ACT.’ Department of Environment and Conservation, Sydney.

Peake T.C.(2005). The Vegetation of the Central Hunter Valley, New South Wales. A Report on the Findings of the Hunter Remnant Vegetation Project. Final Draft Version 1.Hunter – Central Rivers Catchment Management Authority, Paterson.

Thackway R, Cresswell ID (1995) (eds) ‘An interim biogeographic regionalisation of Australia: a framework for establishing the national system of reserves.’ (Version 4.0 Australian Nature Conservation Agency: Canberra).

Thomas D (1998) ‘Vegetation communities of the Singleton Military Area.’ Department of Defence, Singleton.