White Gum Moist Forest in the NSW North Coast Bioregion - endangered ecological community listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list White Gum Moist Forest in the NSW North Coast Bioregion as an ENDANGERED ECOLOGICAL COMMUNITY in Part 3 of Schedule 1 of the Act. Listing of endangered ecological communities is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. White Gum Moist Forest in the NSW North Coast Bioregion is the name given to the ecological community dominated by White Gum, Eucalyptus dunnii, either in pure stands or with  E.saligna, E.microcorys and/or  Lophostemon confertus. The community is characterised by the species listed in paragraph 2, and at maturity typically has a tall open canopy of eucalypts with a structurally complex understorey of rainforest trees and shrubs, vines, palms and ferns. Structural characteristics of the community may vary, depending on the intensity and characteristics of past disturbances including fire, logging, insect attack and partial clearing.

2. White Gum Moist Forest is characterised by the following assemblage of species:

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. White Gum Moist Forest is dominated by an open tree canopy of Eucalyptus dunnii (White Gum) , sometimes with  Eucalyptus saligna (Sydney Blue Gum) ,E.microcorys (Tallowwood) and/or  Lophostemon confertus (Brush Box) . The understorey typically includes a diverse and prominent stratum of rainforest trees and shrubs including  Acmena smithii (Lilli pilli),  Acronychia oblongifolia (Common Acronychia),  Cordyline petiolaris (Coast Banksia),  Croton verreauxii (Green Cascarilla),  Cryptocarya microneura (Murrogun),  Diploglottis australis (Native Tamarind),  Eupomatia laurina (Bolwarra),  Guoia semiglauca,  Maclura cochinchinensis (Cockspur Thorn),  Pittosporum multiflorum (Orange Thorn),  Polyscias elegans (Celery Wood) and  Rubus rosifolius (Rose-leaf Bramble). Vines, including  Cissus antarctica (Water Vine),  C.hypoglauca (Giant Water Vine),  Geitonoplesium cymosum (Scrambling Lily) and  Smilax australis (Sarsaparilla), commonly grow over and amongst the understorey shrubs and trees. The groundcover comprises: ferns, including  Adiantum formosum (Giant Maidenhar),  Doodia aspera (Rasp Fern) and  Lastreopsis spp. (Shield Ferns); herbs, including  Dioscorea transversa (Native Yam) and  Alpinia caerulea (Native Ginger); and graminoids including  Imperata cylindrica var.  major (Blady Grass) and  Lomandra longifolia (Spiny-headed Matrush). Mature stands of the community are typically tall open-forest or open-forest with a structurally complex, multi-stratum understorey, while regrowth stands or recently disturbed stands may take on the structure of low closed forest or scrub, or may have simplified understorey structure, depending on the nature of the disturbance and the time elapsed since.

5. A number of threatened fauna species use habitat resources associated with White Gum Moist Forest. These include the following:

6. White Gum Moist Forest typically occurs on the escarpment slopes and foothills of the north-east NSW, most commonly between 400 and 650 m elevation, where mean annual rainfall exceeds approximately 1000 mm and has a summer maximum (DEC 2007). Soils that support the community are relatively fertile and derived from basalt or fine-grained sediments, or colluvium or alluvium influenced by the presence of these substrates upslope or upstream. The community is typically found in gullies and on lower slopes, but has been recorded on upper slopes and basalt ridges (Binns 1995). It occurs less commonly on west-facing slopes than on other aspects.

7. White Gum Moist Forest occurs in the NSW North Coast bioregion, as well as adjacent regions in south-east Queensland. In NSW, White Gum Moist Forest is currently known from the local government areas of Clarence Valley, Coffs Harbour, Kyogle and Tenterfield, but may occur elsewhere within the bioregion. In addition to these areas, suitable habitat for the community is predicted to occur within the local government areas of Bellingen, Glen Innes – Severn and Richmond Valley (DEC 2007).

8. White Gum Moist Forest includes ‘Dunn’s White Gum’ (Forest Type 51) of Baur (1989), habitat of Eucalyptus dunnii described by Bension and Hager (1993), ‘ Eucalyptus dunnii’ (Floristic Group 73) of NPWS (1995), ‘ Eucalyptus dunnii’ (Community URBov 8) of Binns (1995) and ‘Dunn’s White Gum Community’ (Forest Ecosystem 45) of NPWS (1999) and DEC (2004). White Gum Moist Forest belongs to the North Coast Wet Sclerophyll Forests vegetation class of Keith (2004).

9. All known records of White Gum Moist Forest occur within two disjunct areas: one in the upper northern reaches of the Richmond River catchment; and the other in the north-eastern foothills of the Dorrigo plateau. Together, these areas comprise a total extent of occurrence of less than 2500 km². The area of suitable habitat within this distribution is estimated to be approximately 1700 km², of which approximately 120 km² was assessed as ‘high quality’ habitat (DEC 2007). A map of forest ecosystems in north-eastern NSW (NPWS 1999), shows less than 1000 ha of ‘Dunn’s White Gum Community’ (Ecosystem 45) throughout the range of Eucalyptus dunnii in NSW, suggesting that less than 1% of modelled suitable habitat is occupied by the community (DEC 2007). Based on available mapping and site records, and using a grid scale of 4 km² (as recommended by IUCN 2006, White Gum Moist Forest is estimated to occupy an area of about 600 km². These estimates indicate that the community has a moderately to highly restricted distribution.

10. Since European settlement, and relative to the longevity of its dominant trees, which live for several hundred years, White Gum Moist Forest has undergone a moderate to large reduction in geographic distribution. Estimates of reduction in the distribution of the community vary from 33% (NPWS 1999) to 50% (Wall 2005). However, the extent of the community prior to clearing may have been under-estimated (DEC 2007), suggesting that reductions have been larger than currently estimated. Isolated remnant trees along Duck, Koreelah, Lindsay, Boomi and Beaury creeks are indicative of a previously more extensive occurrence of the community, prior to land clearing (DEC 2007). White Gum Moist Forest continues to be threatened by clearing, particularly where it occurs on fertile soils in valleys and on river flats that are suitable for agriculture and plantation forestry. Approximately one-third of the remaining suitable habitat occurs on private land, the majority of which has been assessed as high- or medium-capability rural land (DEC 2007). ‘Clearing of native vegetation’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.

11. White Gum Moist Forest has undergone changes in structure, including loss of hollow-bearing trees, as a consequence of timber harvesting. Its dominant tree species are valuable commercial timber species and much of the community is currently in a state of regrowth after past logging activity. Benson and Hager (1993) estimated that less than 10% of the E. dunnii forest they surveyed was in an ‘old growth’ state and that 87% of the trees they sampled had a diameter at breast height of less than 0.5 m. Logging operations continue in stands of the community on state forest and private land, which account for approximately two-thirds of the remaining suitable habitat (DEC 2007). For example, recent logging of the community has been reported in Beaury State Forest (DEC 2007). Loss of hollow-bearing trees, which provide important fauna habitat, and other structural changes associated with timber harvesting are indicative of a large reduction in ecological function of the community. ‘Loss of hollow-bearing trees’ is listed as a Key Threatening Process under the  Threatened Species Conservation Act 1995.

12. White Gum Moist Forest is threatened by forest eucalypt dieback associated with over-abundant Bell Miners and psyllids (Wardell-Johnson et al. 2006, DEC 2007). This complex process is associated with substantial changes in community composition and structure, including the defoliation and eventual death of canopy eucalypts, increased densities of mid-stratum plant species and decline in diversity of small forest birds. Forest dieback affects White Gum Moist Forest across all land tenures, including stands that are now included within Mt Clunie and Yabbra National Parks. Areas of low, moderate and severe forest dieback have been mapped within suitable habitat for White Gum Moist Forest (DEC 2007). A field inspection in November 2006 recorded defoliation of upper stratum trees associated with a dominance of Bell Miners in local bird communities in eight of 16 sites inspected (DEC 2007). The impacts of forest eucalypt dieback are indicative of a large reduction in ecological function of the community.

13. White Gum Moist Forest is also potentially threatened by grazing and inappropriate fire regimes. Cattle grazing is practiced in large areas of freehold and leasehold eucalypt forest in north-east NSW, including White Gum Moist Forest. Frequent burning of the understorey is carried out as part of forest management for both cattle production and timber production. Benson & Hager (1993) were able to distinguish the species composition of White Gum Moist Forest sites that appeared to be unburnt for more than 30 years from those that appeared to have been burnt more regularly. The less frequently burnt sites were richer in fire-sensitive rainforest species than the latter, while recently logged and burnt sites had the lowest species diversity (Benson & Hager 1993). More generally, frequent burning and grazing are associated with changes in the structure, diversity and composition of a range of eucalypt forest communities in northern NSW (York 1999, 2000, Andrew et al. 2000, Henderson and Keith 2002, Harris  et al. 2003, York and Tarnawski 2004, Tasker and Bradstock 2006). ‘High frequency fire resulting in disruption of life cycle processes in plants and animals and loss of vegetation structure and composition’ is listed as a Key Threatening Process under the  Threatened Species Conservation Act 1995.

14. Clearing activity, forest dieback, grazing, frequent burning and other disturbances accelerate the invasion of weeds into White Gum Moist Forest. Principal weed species include Lantana camara,  Ochna serrulata and  Senna septemtrionalis.  Lantana camara was recorded in 40% of 43 documented sites of White Gum Moist Forest, and dominated the mid stratum at most of these sites. Infestations of this species have been implicated in forest eucalypt dieback (Wardell-Johnson  et al. 2006). The invasion and establishment of exotic species in White Gum Moist Forest results in a large reduction in the ecological function of the community. ‘Invasion, establishment and spread of  Lantana camara’ is listed as a Key Threatening Process under the  Threatened Species Conservation Act 1995.

15. Eucalyptus dunnii is grown in commercial timber plantations in northern NSW. Until relatively recently, these plantations were grown from seed that was harvested from wild populations, however, an increasing proportion of seed is now produced from controlled breeding stock in seed orchards. The level of gene flow from plantation stock into wild populations is currently unknown, as is the impact of genetic contamination from controlled breeding stock on fitness and genetic diversity of wild populations.

16. Limited examples of the community are have been mapped and recorded from Koreelah, Mt Clunie, Richmond Range, Tooloom, Toonumbar and Yabbra National Parks, Captains Creek and Hortons Creek Nature Reserves. Small stands may also occur within Border Ranges, Chaelundi and Mt Nothofagus National Parks. The remaining stands occur primarily on private land or state forest.

17. White Gum Moist Forest in the NSW North Coast Bioregion is not eligible to be listed as a critically endangered ecological community.

18. White Gum Moist Forest in the NSW North Coast 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.

Clause 27

The ecological community has undergone, is observed, estimated, inferred or reasonably suspected to have undergone or is likely to undergo within a time span appropriate to the life cycle and habitat characteristics of its component species:

(b) a large reduction in ecological function,

as indicated by any of the following:

(d) change in community structure

(e) change in species composition

(f) disruption of ecological processes

(g) invasion and establishment of exotic species

(h) degradation of habitat

Professor Lesley Hughes
Chairperson
Scientific Committee

Proposed Gazettal date: 04/07/08

Exhibition period: 04/07/08 – 29/08/08

References

Andrew N, Rodgerson L, York A (2000) Frequent fuel reduction burning: the role of logs and associated leaf litter in the conservation of ant biodiversity. Austral Ecology 25 , 99-107.

Baur GN (1989) ‘Research Note 17 Forest Types in New South Wales.’  Forestry Commission of New South Wales, Sydney.

Benson JS, Hager T (1993) The distribution, abundance and habitat of Eucalyptus dunnii (Myrtaceae) (Dunn’s White Gum) in New South Wales.  Cunninghamia3 , 123-145.

Binns DL (1995) Urbenville Forestry Management Area Environmental Impact Statement - Flora Survey. State Forests of New South Wales, Coffs Harbour.

DEC (2004) Natural Resource Management Field Assessment Guidelines Field key to Forest Ecosystems North East New South Wales. NSW Department of Environment & Conservation, Coffs Harbour.

DEC (2007) Nomination to list White Gum (Eucalyptus dunnii) very tall to extremely tall moist forest on high nutrient soils in the New South Wales North Coast Bioregion as an Endangered Ecological Community under the NSW TSC Act 1995. Department of Environment and Conservation, Coffs Harbour.

Henderson M, Keith DA (2002) Correlation of burning and grazing indicators with the composition of the woody understorey flora of dells in a temperate eucalypt forest. Austral Ecology 27,  121-131.

Harris R, York A, Beattie AJ (2003) Impacts of grazing and burning on spider assemblages in dry eucalypt forests of north-eastern New South Wales, Australia. Austral Ecology 28 , 526-538.

IUCN (2006) Guidelines for using the IUCN Red List Categories and Criteria: Version 6.1. Species Survival Commission, Standards and Petitions Working Group. http://www.iucnredlist.org/info/categories_criteria

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.

NPWS (1995) Vegetation Survey and Mapping of Upper North East NSW. Report to the Natural Resources Audit Council. NSW National Parks & Wildlife Service, Grafton.

NPWS (1999) Forest ecosystem classification and mapping for the upper and lower north east Comprehensive Regional Assessment. Report to Resource and Conservation Division, Department of Urban Affairs and Planning, Sydney.

Tasker EM, Bradstock RA (2006) Influence of cattle grazing practices on forest understorey structure in north-eastern New South Wales. Austral Ecology31 ,490-502.

Stone C (2005) Bell miner associated dieback at the tree crown scale: A multitrophic process.  Australian Forestry 68 , 237-241.

Thackway R, Cresswell ID (1995). An Interim Biogeographic Regionalisation for Australia: a framework for establishing the national system of reserves, Version 4.0. (Australian Nature Conservation Agency: Canberra.)

Wall J (2005) A vegetation map for the Northern Rivers Catchment Management Authority to support application of the Biodiversity Forecasting Toolkit. Eco Logical Australia Pty Ltd, Coffs Harbour.

Wardell-Johnson G, Stone C, Recher H, Lynch J (2006) Bell Miner Associated Dieback (BMAD) Independent Scientific Literature Review. A review of eucalypt dieback associated with Bell miner habitat in north-eastern New South Wales. Occasional Paper DEC 2006/116. NSW Department of Environment and Conservation, Coffs Harbour.

York A (1999) Long-term effects of repeated prescribed burning on forest invertebrates: management implications for the conservation of biodiversity. Pp 181-266 in: ‘Australia’s biodiversity - responses to fire: plants, birds and invertebrates’ (Eds. AM Gill, JCZ Woinarski, A York). Biodiversity Technical Paper No. 1. Environment Australia, Canberra.

York A (2000) Long-term effects of frequent low-intensity burning on ant communities in coastal blackbutt forests of southeastern Australia. Austral Ecology 25 , 83-98.

York A, Tarnawski J (2004) Impacts of grazing and burning on terrestrial invertebrate assemblages in dry eucalypt forests of north-eastern New South Wales: Implications for biodiversity conservation. Pp. 845-859 in: ‘Conservation of  Australia 's Forest Fauna’ (Ed. D Lunney). Second edition. Royal Zoological Society of NSW, Mosman.