Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions - endangered ecological community listin

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions, 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. Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions is the name given to the ecological community that generally occurs on floodplains and associated floodplain rises along the Hunter River and tributaries and is characterised by the assemblage of species in paragraph 2. The community typically forms a tall woodland. All sites are within the NSW North Coast and Sydney Basin Bioregions. Those sites within the NSW North Coast Bioregion are in the southern part of the bioregion.

2. Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions 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, flooding or drought condition and by its disturbance (including fire and grazing) history. The number of species, and the above ground relative abundance of species will change with time since disturbance, and may also change in response to changes in disturbance regime (including changes in flood 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. Hunter Floodplain Red Gum Woodland typically forms a tall to very tall (18-35 m) woodland. Stands on major floodplains are generally dominated by Eucalyptus  camaldulensis (River Red Gum) in combinations with  Eucalyptus tereticornis (Forest Red Gum),  Eucalyptus melliodora (Yellow Box) and  Angophora floribunda (Rough-barked Apple). Within the community stands of  Casuarina cunninghamiana subsp.  cunninghamiana (River Oak) and  Casuarina glauca (Swamp Oak) can form a part of this community. Dominant groundcovers include  Cynodon dactylon (Couch),  Alternanthera denticulata (Lesser Joyweed),  Austrostipa verticillata (Slender Bamboo Grass),  Dichondra repens (Kidney Weed),  Lepidium pseudohyssopifolium (Peppercress),  Pratia concolor (Poison Pratia),  Urtica incisa (Stinging Nettle),  Einadia hastata (Berry Saltbush),  Amaranthus macrocarpus var.  macrocarpus (Dwarf Amaranth),  Cyperus fulvus (Sticky Sedge),  Cynoglossum australe (Australian Hound’s Tongue),  Cyperus  gracilis, (Sedge),  Glycine tabacina (Variable Glycine),  Geranium solanderi var.  solanderi (Native Geranium) and  Microlaena stipoides var.  stipoides (Weeping Rice Grass).

5. Hunter Floodplain Red Gum Woodland generally occurs on floodplains and floodplain rises. Hunter Floodplain Red Gum Woodland has been described by Peake (2006) and Umwelt (2008) and, in part, by NSW NPWS (2000). Hill (2003) describes the same comminuty as Central Hunter Riparian Forest.

6. Hunter Floodplain Red Gum Woodland has been recorded from the local government areas of Maitland, Mid-Western, Muswellbrook, Singleton, and Upper Hunter but may occur elsewhere within the NSW North Coast and Sydney Basin Bioregions (sensu Thackway and Creswell 1995).

7. Hunter Floodplain Red Gum Woodland occupies an area of less than 500 km² based on 2 x 2 km grid cells, the scale of assessment recommended for species by IUCN (2008). Mapped occurrences of the community include a few remnants greater than 10 ha and many small remnants less than 10 ha indicating severe fragmentation (Peake 2006). Within the Central Hunter Valley it is estimated that the geographic distribution of the community has been reduced by more than 90% of its pre-European extent (Peake 2006).

8. Hunter Floodplain Red Gum Woodland is known to contain an endangered population of Eucalyptus camaldulensis listed under the  Threatened Species Conservation  Act 1995.

9. Threats to Hunter Floodplain Red Gum Woodland include changed hydrology associated with climate change, clearing, fertilizer application, flood mitigation, herbicide application, trampling and grazing by cattle, and weed invasion. The community is also vulnerable to stochastic events due to its highly fragmented distribution and the small size of remnant patches. These threats are escalating and are intensified by the absence of regular flooding to stimulate the recruitment of Eucalyptus camaldulensis (Murray Darling Basin Commission 2003). The introduction of  Eucalyptus camaldulensis cultivars not native to the Hunter Valley and hybrids may also threaten the genetic integrity of native River Red Gums (Meddings  et al. 2003; Potts  et al. 2003). Removal of the native understorey for dairying and cropping has resulted in the invasion of weed species and changed community structure. These weed species include  Pennisetum clandestinum (Kikuyu),  Galenia pubescens (Galenia),  Ehrharta erecta (Panic Veldtgrass),  Axonopus affinis (Carpet Grass),  Alternanthera pungens (Khaki Weed) and  Ricinis communis (Caster Oil Plant). The presence of weeds, grazing and fertilizer application is limiting the recruitment of understorey plants and tree species. 'Anthropogenic climate change', 'Clearing of native vegetation', 'Alteration to the natural flow regimes of rivers and streams and their floodplains and wetlands', 'Invasion of native plant communities by exotic perennial grasses', and 'Invasion and establishment of exotic vines and scramblers' are listed as Key Threatening Processes under the  Threatened Species  Conservation Act 1995. 'Degradation of native riparian vegetation along NSW water courses' is listed as a Key Threatening Process under the  Fisheries Management  Act 1994. Collectively, the effects of these threats indicate a large reduction in the ecological function of the community.

10. Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions is eligible to be listed as an Endangered Ecological Community as, in the opinion of the Scientific Committee, it is facing a high risk of extinction in New South Wales in the immediate future, as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:

Clause 25

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 geographic distribution.

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:

(g) invasion and establishment of exotic species

(h) degradation of habitat

(i) fragmentation of habitat.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 23/04/10

Exhibition period: 23/04/10 - 18/06/10

References:

Hill L (2003) 'The Natural Vegetation of Maitland Local Government Area'. Report to the Maitland City Council.

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).

Meddings RA, McComb JA, Calver MC, Thomas SR, Mazanec RA (2003) Eucalyptus camaldulensis x globulus hybrids. Australian Journal of Botany51 , 319-331.

Murray–Darling Basin Commission (2003) 'Preliminary investigations into observed River Red Gum decline along the River Murray below Euston'. Technical report 03/03. Murray–Darling Basin Commission, Canberra.

New South Wales National Parks and Wildlife Service (2000) 'Vegetation Survey, Classification and Mapping: Lower Hunter Central Coast region. Version 1.2. A project undertaken for the Lower Hunter and Central Coast Regional Environment Management Strategy'. NSW National Parks and Wildlife Service, Hurstville.

Peake TC (2006) 'The Vegetation of the Central Hunter Valley, New South Wales'. A report on the findings of the Hunter Remnant Vegetation Project. Hunter - Central Rivers Catchment Management Authority, Paterson.

Potts BM, Barbour RC, Hingston AB, Vaillancourt RE (2003) Turner review No. 6. Genetic pollution of native eucalypt gene pools - identifying the risks. Australian Journal of Botany51 , 1-25.

Thackway R, Creswell ID (1995) 'An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserve System Cooperative Program'. Version 4.10. ANCA, Canberra.

Umwelt (Australia) Pty Ltd (2008) ‘ River Red Gum post flood assessment and description of ecological character’. Report to Department of Environment and Climate Change, December 2008.