Araluen Scarp Grassy Forest in the South East Corner 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 Araluen Scarp Grassy Forest in the South East Corner Bioregion (as described in the determination of the Scientific Committee under Division 5 Part 2) and as a consequence to omit reference to the Araluen Scarp Grassy Forest in the South East Corner Bioregion (as described in the final determination to list the ecological community) which was published on pages 3465 to 3468 in the NSW Government Gazette No. 92 dated 16 July 2010. 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. Araluen Scarp Grassy Forest in the South East Corner Bioregion is the name given to the community characterised by the assemblage of species listed in paragraph 2 and typically comprising eucalypt tree canopy with an open shrub layer and a grassy groundcover. The community is largely restricted to the escarpment and associated ridges on the northern and western sides of the Araluen valley. It occurs typically on sandy loams derived from granite, usually on steep slopes between approximately 200-700 m ASL. This distribution falls within a rain shadow zone, where mean annual rainfall is approximately 890-1000 mm.

2. Araluen Scarp Grassy Forest in the South East Corner Bioregion is characterised by the following assemblage of species:

Other tree species occurring less frequently in this community include:

3. The total species list of the community is considerably larger than that given above, with many species present in only 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 condition and by its disturbance (including fire) history. The number of species, and the above ground relative abundance of species will change with time since fire, and may also change in response to changes in fire regime (including changes in fire frequency). 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 plant species; 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. Araluen Scarp Grassy Forest in the South East Corner Bioregion is characterised by an overstorey that is usually dominated by Eucalyptus melliodora (Yellow Box),  E. maidenii (Maidens Gum)  and  Acacia mearnsii (Black Wattle). Other trees include  E. globoidea (White Stringybark) and  E. tereticornis (Forest Red Gum). The understory often includes an open shrub stratum of small trees dominated by  Melicytus dentatus and  Pittosporum undulatum. The  grassy ground cover is dominated by  Microlaena stipoides (Weeping Grass) and  Oplismenus imbecillis with forbs such as  Dichondra repens (Kidney Weed) , Desmodium varians (Slender Tick Trefoil) , Hydrocotyle laxiflora (Stinking Pennywort) , Hypericum gramineum (Small St John's Wort) , Glycine clandestina and the fern  Cheilanthes sieberi (Poison Rock Fern) . The structure of the community varies depending on past and current disturbances, particularly clearing and grazing. After total or partial clearing, the tree canopy may remain sparse or may regrow to form dense stands of saplings and small trees, which are typically associated with a ground layer of reduced cover and diversity. Either or both of the overstorey and mid-stratum may be absent from the community. Native grasslands derived from clearing of the woodland and forest are also part of this community if they contain characteristic non-woody species listed in paragraph 2.

5. Araluen Scarp Grassy Forest in the South East Corner Bioregion includes: Araluen Acacia Herb/Grass Dry Forest – E. melliodora / E. maidenii (forest ecosystem 51) of Thomas  et al. (2000), Araluen Scarp Grassy Forest (map unit 343) of Tindall  et al. (2004); Araluen Scarp Grassy Forest (map unit p343) of Tozer  et al. (2004); and parts of Araluen Acacia Herb Dry Grass Forest  Eucalyptus melliodora / E. maidenii (map unit g51) of Gellie (2005). Araluen Scarp Grassy Forest in the South East Corner Bioregion is strongly associated with steeper slopes and, locally, is replaced on the gently undulating valley floor by Araluen Valley Grassy Woodland (map unit GW e20 p229) (Tozer  et al. 2004). The former is dominated by  E. melliodora and  E. maidenii with  Acacia mearnsii as a sub-dominant while  E. tereticornis and  E. globoidea tend to dominate on the flats, with  A. mearnsii and  A. implexa as sub-dominants.  Eucalyptus melliodora and  E. maidenii may also occur in Araluen Valley Grassy Woodland but are much less common than on the steeper slopes. Araluen Scarp Grassy Forest has a much sparser and much less diverse coverage of grass species than Araluen Valley Grassy Woodland which may be further distinguished from the latter by a representation of species characteristic of moister, more sheltered habitats including  Clematis glycinoides var.  glycinoides,  Ficus rubiginosa,  Marsdenia rostrata,  Melicytus dentatus,  Pandorea pandorana,  Pellaea falcata,  Pittosporum undulatum,  Plectranthus parviflorus and  Sigesbeckia orientalis subsp.  orientalis. On the summit of the escarpment, Araluen Scarp Grassy Forest grades into Southern Tablelands Flats Forest (map unit GW p220 Tozer  et. al 2004) which is dominated by tableland species such as  E. viminalis and  E. pauciflora, and  A. mearnsii is replaced by  A. melanoxylon. Southern Tablelands Flats Forest lacks the moister, more sheltered species of Araluen Scarp Grassy Forest. Mountain Wet Fern Forest (map unit WSF e12) may also be found on the higher peaks of the escarpment (Tozer  et al. 2004). This community is readily distinguishable from Araluen Scarp Grassy Forest by the dominance of  E. cypellocarpa and  E. fastigata with a diverse representation of ground ferns and tree ferns in the understorey (Tozer  et al. 2004). Araluen Scarp Grassy Forest in the South East Corner Bioregion belongs to the Southern Hinterland Dry Sclerophyll Forests vegetation class of Keith (2004).

6. Araluen Scarp Grassy Forest in the South East Corner Bioregion is currently known to occur within the Eurobodalla and Palerang Local Government Areas, but may occur elsewhere in the bioregion. Bioregions are defined in Thackway and Cresswell (1995). Approximately 2 400 ha of the community are mapped in conservation reserves, equating to 15-30% of its pre-European distribution, with most of the remaining area occurring on freehold tenure (Tozer et al. 2004).

7. Since European settlement, and relative to the longevity of its dominant trees which live for several hundred years, Araluen Scarp Grassy Forest in the South East Corner Bioregion has undergone an estimated 10-25% reduction in geographic distribution due to clearing (Tozer et al. 2004). The extent of occurrence is approximately 350 km² and the area of occupancy is 300 km², based on a minimum convex polygon and a 2 x 2 km grid, respectively, as recommended by IUCN (2008). The geographic distribution of the community is inferred to be highly restricted with the total remaining area estimated to be approximately 9 000 ha (Tozer et al. 2004). Estimates by Thomas  et al. (2000) and Gellie (2005) were based on fewer sites and broader mapping.

8. Like other Southern Hinterland Dry Sclerophyll Forests, steep terrain has prevented extensive clearing of Araluen Scarp Grassy Forest in the South East Corner Bioregion (Tozer et al. 2004) although patch clearing associated with agriculture and development of hobby farms may be threatening the community (EcoGIS 2001). Much of this forest is used for rough-country cattle grazing, especially on the lower slopes (Tozer  et al. 2004, D. Keith pers. comm. 2009), and the understorey and erodible soils are also impacted by feral goats (Tozer  et al. 2004). Locally and/or periodically heavy grazing of Araluen Scarp Grassy Forest by domestic livestock and feral pests results in the decline and disappearance of palatable plant species, including shrubs and herbs, and compaction and erosion of topsoil, making it difficult for a diverse native understorey to re-establish. The effects of such overgrazing may be exacerbated under drought conditions. The community is susceptible to extreme dry spells which may increase in duration and magnitude under climate change. Field sampling in 2003-04 identified extensive dieback of eucalypt crowns and understoreys attributed to recent extended drought, particularly on the spurs of the escarpment (Tozer  et al. 2004, D. Keith pers. comm.). Death of leaf canopies was especially pronounced in stringybark eucalypts, suggesting differential susceptibility between species and potential changes in community composition as a result. ‘Competition and habitat degradation by Feral Goats  Capra hircus’ and ‘Anthropogenic Climate Change’ are listed as Key Threatening Processes under the  Threatened Species Conservation Act 1995.

9. Weed invasion may be threatening the ecological function of Araluen Scarp Grassy Forest in the South East Corner Bioregion with parts of the community potentially subject to invasion by pastoral weeds. Survey work to date has focused on the best examples of the community, hence little is known about the patches worst-affected by weeds. The following introduced species however are known to occur within Araluen Scarp Grassy Forest in the South East Corner Bioregion:

10. Habitat degradation associated with overgrazing, erosion and weed invasion is contributing to a moderate reduction in ecological function of Araluen Scarp Grassy Forest in the South East Corner Bioregion.

11. Araluen Scarp Grassy Forest in the South East Corner Bioregion is not eligible to be listed as a Critically Endangered Ecological Community.

12. Araluen Scarp Grassy Forest in the South East Corner Bioregion is eligible to be listed as an Endangered Ecological Community as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near future, as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:

Clause 26

The ecological community’s geographic distribution is estimated or inferred to be:

(b) highly restricted

and the nature of its distribution makes it likely that the action of a threatening process could cause it to decline or degrade in extent or ecological function over a time span appropriate to the life cycle and habitat characteristics of the ecological community’s component species.

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 2010 as indicated in the determination

References:

EcoGIS (2001) ‘Vulnerable Ecosystems of Eurobodalla Shire.’ Report to Eurobodalla Shire Council.

Gellie NJH (2005) Native vegetation of the southern forests: South-east Highlands, Australian Alps, South-west Slopes and South-east Corner Bioregions. Cunninghamia 9, 219-254.

IUCN (2008) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland).

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

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.)

Thomas V, Gellie N, Harrison T (2000) ‘Forest Ecosystem Classification and Mapping for the Southern CRA Region.’ Report for the NSW CRA/RFA Steering Committee, Project No. NS 08EH. NSW National Parks and Wildlife Service, Queanbeyan.

Tindall D, Pennay C, Tozer MG, Turner K, Keith DA (2004) ‘Native vegetation map report series. No. 4. Araluen, Batemans Bay, Braidwood, Burragorang, Goulburn, Jervis Bay, Katoomba, Kiama, Moss Vale, Penrith, Port Hacking, Sydney, Taralga, Ulladulla, Wollongong.’ NSW Department of Environment and Conservation and NSW Department of Infrastructure, Planning and Natural Resources, Sydney.

Tozer MG, Turner K, Keith DA, Simpson C, Beukers P, Mackenzie B, Tindall D, Pennay C (2004) ‘Native vegetation of southeast NSW: a revised classification and map for the coast and eastern tablelands.’ Version 1.0. NSW Department of Environment and Conservation and NSW Department of Natural Resources, Sydney.