Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions - Determination to make a minor amendment to Part 3 of Schedule 1 of the Threatened Species Conservation Act

NSW Scientific Committee

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 Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions (as described in the determination of the Scientific Committee under Division 5 Part 2) and as a consequence to omit reference to the Grey Box - Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions (as described in the final determination to list the ecological community) which was published on pages 1912 to 1916 in the NSW Government Gazette No. 56 dated 23 April 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 and species names.

 

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. Bioregions are defined in Thackway and Cresswell (1995).

 

2. Hunter Floodplain Red Gum Woodland in the NSW North Coast and Sydney Basin Bioregions is characterised by the following assemblage of species:

 

Alternanthera denticulata

Amaranthus macrocarpus var. macrocarpus

Angophora floribunda

Aristida ramosa

Austrodanthonia fulva

Austrostipa verticillata

Brachychiton populneus subsp. populneus

Calotis lappulacea

Carex inversa

Casuarina cunninghamiana subsp. cunninghamiana

Cheilanthes austrotenuifolia

Chrysocephalum apiculatum

Commelina cyanea

Cynodon dactylon

Cynoglossum australe

Cyperus fluvus

Cyperus gracilis

Dichondra repens

Echinopogon caespitosus var. caespitosus

Einadia hastata

Eindadia trigonos subsp. trigonos

Eucalyptus camaldulensis

Eucalyptus melliodora

Eucalyptus tereticornis

Geranium solanderi var. solanderi

Glycine tabacina

Lepidium pseudohyssopifolium

Marsilea drummondii

Melia azedarach

Microlaena stipoides var. stipoides

Notelaea microcarpa var. microcarpa

Oxalis exilis

Plantago debilis

Pratia concolor

Pratia purpurascens

Rumex brownii

Urtica incisa

 

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 Cresswell 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: 08/07/11

Exhibition period: 08/07/11 - 02/09/11

 

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). (http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf).

 

Meddings RA, McComb JA Calver, MC, Thomas SR, Mazanec RA (2003) Eucalyptus camaldulensis x globulus hybrids. Australian Journal of Botany 51, 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 Botany 51, 1-25.

 

Thackway R, Cresswell ID (1995) 'An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserve System Cooperative Program'. (Version 4.0 Australian Nature Conservation Agency: 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.

Page last updated: 08 July 2011