Ribbon Gum-Mountain Gum-Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion - minor amendment Determination

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. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion is the name given to the ecological community characterised by the assemblage of species listed in paragraph 2 that typically occurs at elevations of 700 - 1500 m, and is mainly confined to the high undulating basalt plateau with deep, chocolate or krasnozem loam soils (Benson and Ashby 2000). The structure of the community is typically open forest 20 – 30 m tall, although it may assume the structure of woodland, sometimes less than 12 m tall, in exposed sites or where subject to past clearing or thinning. The understorey contains a sparse stratum of shrubs and a continuous groundcover composed mostly of grasses and herbs.

2. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion is characterised by the 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, 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 regimes. 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 mainly of vascular plant species, however the community also includes micro-organisms, fungi, cryptogamic plants and a diverse fauna, both vertebrate and invertebrate. These components of the community are poorly documented.

4. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion is characterised by a tree layer usually c. 20 m tall, reaching up to 30 m in resource-rich sites, but considerably shorter than 20m on exposed or damp sites or where past clearing has removed mature trees. Common overstorey species include Eucalyptus viminalis (Ribbon Gum), E. dalrympleana subsp. heptantha (Mountain Gum), E. pauciflora (Snow Gum or White Sallee) and occasionally E. stellulata (Black Sallee). The understorey comprises a sparse layer of shrubs including Acacia dealbata, Pultenaea microphylla and Pimelea linifolia and a dense to very dense grassy ground cover dominated by Poa sieberiana var. sieberiana, P.labillardieri var. labillardieri, Themeda australis and Elymus scaber with herbs such as Acaena spp. Ammobium alatum, Asperula conferta, Geranium solanderi, Ranunculus lappaceus and numerous other species (Benson and Ashby 2000).

5. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion provides important habitat for the nationally vulnerable plant species Thesium australe, commonly known as ‘Austral Toadflax’ (Benson and Ashby 2000).

6. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion is currently known from parts of the Local Government Areas of Armidale Dumaresq, Bellingen, Clarence Valley, Glen Innes Severn, Guyra, Inverell, Tenterfield, Uralla and Walcha but may occur elsewhere in this bioregion. Bioregions are defined in Thackway and Cresswell (1995).

7. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion includes Communities 6 and 7 of Benson and Ashby (2000) and Tableland Grasslands and Woodlands on Basaltic Soils (Vegetation Type 1b, Eucalyptus viminalis) of Clarke et al. (1995). There may be additional occurrences of the community within and beyond these surveyed areas. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland belongs to the Tableland Clay Grassy Woodlands vegetation classs (Keith 2004).

8. Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion may co-occur with White Box Yellow Box Blakely's Red Gum Woodland, also listed under the Threatened Species Conservation Act (1995). The two Endangered Ecological Communities may intergrade where they adjoin and in intermediate habitats such as occur in the vicinity of Armidale. All intermediate assemblages are collectively included within the two communities.

9. The extent of Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion prior to European settlement has not been mapped across its entire range. However, in the Guyra District, Benson and Ashby (2000) estimate that 85% of their Map Units 6 and 7 have been cleared, leaving less than 8500 ha, of which less than half still retains a largely native understorey. This indicates a large reduction in geographic distribution of the community. Throughout the range of this community most of the understorey is highly modified, with many weeds present and a reduced native species richness (J. T. Hunter pers. comm.). An unknown area persists as native grassland where the woody component of the community has been eliminated by clearing. Of the area still wooded, much is regrowth after clearing or has had its understorey adversely affected by grazing or weed invasion.

10. The remaining stands are severely fragmented by past clearing and further threatened by continuing fragmentation and degradation, high grazing pressure, inappropriate fire regimes and invasion by introduced taxa (Benson and Ashby 2000, Keith 2004). Common introduced taxa include Hypochaeris radicata, Trifolium repens, Cirsium vulgare, Taraxacum officinale, Arenaria leptoclados and Petrorhagia nanteullii (Benson and Ashby 2000). Exotic perennial grasses such as Eragrostis curvula and Andropogon virginicus also threaten the community at higher altitudes (J. T. Hunter pers. comm.). Grazing pressure within remnant stands may be intense at certain times and high frequency (in some cases, annual) fires are a common management practice, leading to reduced understorey diversity. Most remnants are in poor condition, with some of the best examples now found along roadsides where they are often susceptible to gradual attrition due to road maintenance activities (J. T. Hunter pers. comm.). Collectively these processes represent a large reduction in the ecological function of the community. Clearing of native vegetation, High frequency fire resulting in disruption of life cycle processes in plants and animals and loss of vegetation structure and composition and Invasion of native plant communities by exotic perennial grasses are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995.

11. The community is poorly represented in conservation reserves with only 17 ha represented in Little Llangothlin Nature Reserve (Benson and Ashby 200).

12. In view of the above, the Scientific Committee is of the opinion that Ribbon Gum - Mountain Gum - Snow Gum Grassy Forest/Woodland of the New England Tableland Bioregion is likely to become extinct in nature in New South Wales 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

Benson JS, Ashby EM (2000) The natural vegetation of the Guyra 1:100 000 map sheet, New England Tableland Bioregion of New South Wales. Cunninghamia 6, 747-872.

Clarke PJ, White GJ, Beckers D, Williams JB, Whalley RDB, Bruhl JJ, Able E (1995) Survey and Assessment of plant species and vegetation along the proposed EASTLINK powerline corridor between Armidale, New South Wales and Gatton, Queensland. Botany Department, University of New England.

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

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).