Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions - endangered ecological community listing
NSW Scientific Committee - final determination
The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South 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.
The Scientific Committee has found that:
1. Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions is the name given to the ecological community found on the grey, self-mulching clays of periodically waterlogged floodplains, swamp margins, ephemeral wetlands, and stream levees. The structure of the community may vary from tall riparian woodlands to very open 'savanna like' grassy woodlands with a sparse midstorey of shrubs and saplings. The latter is the more common structural form, generally with a crown cover greater than 0.2%, although this may be less in areas subjected to tree clearing or ring-barking. Typically these woodlands form mosaics with grasslands and wetlands.
The composition of the suite of plant assemblages that comprise this ecological community is primarily determined by the frequency and duration of inundation by overbank floods. As a consequence, species composition varies from the channelised parts of the floodplain to the less frequently inundated outer parts of the floodplain. The community is characterised by the following assemblage of species:
| Abutilon oxycarpum | Acacia cambagei |
| Acacia excelsa | Acacia pendula |
| Acacia salicina | Acacia stenophylla |
| Alectryon oleifolius subsp. elongatus | Alstonia constricta |
| Alternanthera nodiflora | Apophyllum anomalum |
| Aristida platychaeta | Astrebla lappacea |
| Atalaya hemiglauca | Atriplex leptocarpa |
| Atriplex muelleri | Atriplex nummularia |
| Atriplex vesicaria | Austrodanthonia setacea |
| Brachyscome dentata | Brachyscome smithwhitei |
| Capparis lasiantha | Capparis mitchellii |
| Carex inversa | Casuarina cristata |
| Casuarina pauper | Chenopodium nitrariaceum |
| Chloris truncata | Chloris ventricosa |
| Cyperus bifax | Cyperus concinnus |
| Cyperus victoriensis | Dactyloctenium radulans |
| Daucus glochidiatus | Dichanthium sericeum subsp. sericeum |
| Einadia nutans subsp. nutans | Eleocharis acuta |
| Eleocharis pallens | Eleocharis plana |
| Eleocharis pusilla | Enchylaena tomentosa |
| Enteropogon acicularis | Eragrostis setifolia |
| Eremophila bignoniiflora | Eremophila maculata |
| Eremophila mitchellii | Eucalyptus camaldulensis |
| Eucalyptus coolabah | Eucalyptus largiflorens |
| Eucalyptus populnea subsp. bimbil | Geijera parviflora |
| Goodenia pusilla | Lachnagrostis filiformis |
| Leptochloa digitata | Marsilea drummondii |
| Melaleuca trichostachya | Muehlenbeckia florulenta |
| Myoporum montanum | Oxalis chnoodes |
| Panicum decompositum | Panicum subxerophilum |
| Parsonsia eucalyptophylla | Paspalidium distans |
| Paspalidium jubiflorum | Plantago cunninghamii |
| Pratia concolor | Pycnosorus globosus |
| Rhagodia spinescens | Salsola tragus subsp. tragus |
| Sclerolaena bicornis var. bicornis | Sclerolaena birchii |
| Sclerolaena calcarata | Sclerolaena intricata |
| Sclerolaena muricata var. muricata | Sclerolaena tubata |
| Solanum esuriale | Sporobolus caroli |
| Swainsona galegifolia | Tetragonia tetragonioides |
| Thyridolepis mitchelliana | Tribulus micrococcus |
2. The total species list of the community is considerably larger than that given above, with many species present at 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 conditions and by its disturbance (including grazing, flooding, fire and land clearing) history. The number and relative abundance of species will change with time since flooding or fire, and may also change in response to changes in grazing, water and fire regimes (including changes in fire or flood frequency, grazing intensity, etc.). 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.
3. Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions is currently known from parts of the Local Government Areas of Brewarrina, Central Darling, Cobar, Coonamble, Moree Plains, Narrabri, and Walgett but may occur elsewhere in these bioregions. Bioregions are defined in Thackaway and Creswell (1995).
4. Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions is usually formed as a woodland or open woodland with a grassy groundlayer but the composition of this layer will vary depending on past grazing pressure. Eucalyptus coolabah (Coolibah) is typically the most common tree in this community, and it may occur with or without Acacia stenophylla (River Cooba), Acacia salicina (Cooba), Casuarina cristata (Belah), Eremophila bignoniiflora (Eurah), Eucalyptus largiflorens (Black Box), and Eucalyptus populnea subsp. bimbil (Bimble Box). Eucalyptus largiflorens (Black Box) may become the dominant tree species on parts of the central-northern riverine plains and on slightly more elevated parts of the floodplain, but is less common in the north-eastern part of the community's distribution. Eucalyptus populnea subsp. bimbil (Bimble Box) may occur on the outer floodplain, while Eucalyptus camaldulensis (River Red Gum) is generally restricted to the vicinity of the stream channels. The typically sparse midstorey includes Muehlenbeckia florulenta (Lignum), which is most common close to the stream channels and in depressions, and Alectryon oleifolius subsp. elongatus (Rosewood), Alstonia constricta, Eremophila bignoniiflora, Eremophila mitchellii (Budda), Geijera parviflora (Wilga), and Rhagodia spinescens. The understorey may include Astrebla lappacea (Mitchell Grass), Cyperus victoriensis (Yelka), Dactyloctenium radulans (Button Grass), Daucus glochidiatus (Native Carrot), Dichanthium sericeum (Queensland Bluegrass), Eragrostis setifolia (Neverfail), Paspalidium jubiflorum (Warrego Summer Grass), Panicum decompositum (Native Millet), Paspalidium distans, Plantago cunninghamii (Sago-weed), Pycnosorus globosus (Drumsticks), Marsilea drummondii (Common Nardoo) plus exotic species.
5. A number of vegetation mapping studies have been conducted across the Northern Riverine Plains of NSW (Dick 1990, Peasley & Walsh 2001, Sawtell & Miller 2001, Sivertsen & Metcalfe 2001, White 2001, DeVries et al. 2002, Kerr et al. 2003). These all recognise a mapping unit containing Coolibah and Black Box on floodplains but vary in the extent that they include other dominant species such as Eucalyptus camaldulensis (River Red gum) and Eucalyptus populnea subsp. bimbil (Bimble Box) in the mapping unit. The most extensive mapping and detailed floristic survey of the region was by Sivertsen & Metcalfe (2001). Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions ecological community includes their units R3 - Coolibah Red Gum Woodlands and R10 - Open Coolibah Woodlands and also includes some vegetation mapped as R2 - Floodplain Mosaic. Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions ecological community forms part of the North-west Floodplain Woodlands class of Keith (2002, 2004).
6. The extent of the Coolibah - Black Box Woodland of the northern riverine plains ecological community prior to European settlement has not been mapped across its entire range. However, one estimate suggests that Coolibah and Blackbox woodland communities of the frequently flooded channels and outer floodplains of the upper Darling tributaries originally had a combined distribution in New South Wales of about 1.2-2.0 million hectares (J. S. Benson, pers. comm., 2003). One study of the Moree Plains Shire estimated that 'Black Box-Coolabah Floodplain Woodlands' and 'Mixed Bimbil Box and Coolabah Woodlands', together once covered more than 800,000 ha of the Shire, mostly in the western section (White 2001). This estimate may include some Poplar Box communities, but by 2001 only 37% of the original extent was estimated to remain.
7. Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions have been extensively cleared and modified. Overall, more than two-thirds of the original Coolibah woodland communities of the frequently flooded channels and outer floodplains in existence at the time of European settlement is estimated to have been cleared (J. S. Benson, pers. comm., 2003). The greatest extent of change has occurred in the northern parts of the Central Division. For example, less than 20% of the original woodland is estimated to remain on the riverine plains between Moree and Goondiwindi (J. S. Benson, pers. comm., 2003). There has also been considerable modification of the community by ringbarking and poisoning, particularly in the Western Division.
8. Land clearing continues to threaten Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions. A field-validated study based on analysis of aerial photographs in part of the northern riverine plains district, north-east of Walgett, calculated that annual rates of clearing varied between 0.4 and 2.4% per year for several map units dominated by Coolibah woodlands (map units R2, R3 and R10) between 1985 and 2000 (Cox et al. 2001). The study estimated that 12-20 per cent of the coolibah woodlands present on the Moree floodplains in 1985 were cleared over the following 15 years (Cox et al. 2001). The pattern of clearing across the landscape also resulted in increasing fragmentation of what was left, with over half of the remaining woodlands surviving as patches of less than 100 hectares. A recent analysis of clearing rates in the southern part of the range of the Coolibah - Black Box woodlands community indicates that substantial land clearing continued through the 1990s into the twenty-first century, despite the introduction of more stringent regulatory measures during this period (Skully 2003). Advice provided by the Department of Infrastructure, Planning and Natural Resources indicates that approvals issued for clearing of vegetation with woody plant species relevant to Coolibah - Black Box Woodland exceeded 110,000 ha in the Darling Riverine Plains and Brigalow Belt South bioregions between January 1997 and June 2003. The likelihood of continued clearing was foreshadowed in Draft Regional Vegetation Management Plans which were prepared under the Native Vegetation Conservation Act 1996, which proposed to allow for further clearing of this community in the order of tens of thousands of hectares in each of the Moree, Brewarrina and Walgett regions (Brewarrina Regional Vegetation Committee 2002, Moree Regional Vegetation Committee 2002, DLWC 2002). 'Clearing of native vegetation' is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
9. In addition to the direct effects of land clearing, Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions continues to be threatened by fragmentation, overgrazing, weed invasion and the alteration of flood regimes. Drift of herbicides and pesticides may be a concern where remnant patches of woodland occur within an extensive matrix of cropping. Roadside vegetation, for example, may be sprayed inadvertently during aerial spraying of adjacent paddocks, resulting in exposure of bare soil and reduced species richness (J. R. Hosking, pers. comm., 2003). Overgrazing by feral and domestic herbivores, while less extensive in recent decades than in the past (Beadle 1948), may have long-lasting impacts on palatable native plant species, soil erosion, productivity and weed invasion. These impacts are exacerbated during severe droughts. Weeds are abundant in many eastern areas of Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions, but are generally less prevalent in western areas, such as the Culgoa River district (Dick 1990). Weed species of particular concern include Phyla canescens (Lippia) and Lycium ferrocissimum (African boxthorn). The widespread modification of the floodplain by the construction of diversion banks, channels, levees, drains and upstream extraction of water for irrigation has seen considerable changes to seasonality, periodicity, duration, frequency, depth and pattern of flood regimes (Boulton & Brock 1999). Many remnants of this flood-dependent community may be in protracted decline, as individuals of long-lived woody species may persist for many years, but may not be replaced by new plants when they eventually die (Boulton & Brock 1999, White 2001). 'Alteration to the natural flow regimes of rivers, streams, floodplains and wetlands' is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
10. A relatively small area of Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions is contained within existing conservation reserves, and these are primarily located in the western parts of the distribution of the community (e.g. Culgoa National Park, Paroo-Darling National Park). Protected areas in the eastern part of the distribution of this community, including the Macquarie Marshes Nature Reserve, are likely to contain only a few hundred hectares of Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions .
11. In view of the above the Scientific Committee is of the opinion that Coolibah - Black Box Woodland of the northern riverine plains in the Darling Riverine Plains and Brigalow Belt South bioregions is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate
Associate Professor Paul Adam
Chairperson
Scientific Committee
Proposed Gazettal date: 14/05/04
Exhibition period: 14/05/04 - 25/06/04
References:
Beadle NCW (1948) Vegetation and pastures of western New South Wales. Soil Conservation Service: Sydney.
Boulton AJ, Brock M (1999) Australian freshwater ecology: processes and management. Gleneagles Publishing: Glen Osmond, Australia.
Brewarrina Regional Vegetation Committee (2002) Draft Brewarrina Regional Vegetation Management Plan, 29th May 2002. DLWC: Sydney.
Cox J, Sivertsen DP, Bedward M (2001) Clearing of native woody vegetation in the NSW Wheatbelt: extent, rate of loss and implications for biodiversity conservation. Cunninghamia 7, 101-155.
Department of Land and Water Conservation (2002a) Draft Walgett Regional Vegetation Management Plan, Version 17.0, May 16th 2002. DLWC: Sydney.
DeVries R, Cavallaro M, Scott B, Love J, McCauley A, Pelly V, Wild J, Knight H (2002) Vascular flora and vegetation of the Darling Riverine Plains. Unpublished report to NPWS, Western Regional Assessment Unit. NSW NPWS: Dubbo.
Dick R (1990) The vegetation of the Wombeira land system on the floodplains of the Culgoa, Birrie and Narran Rivers in NSW. Occasional Paper No. 13. NSW National Parks and Wildlife Service, Sydney.
Keith DA (2002) A compilation map of native vegetation for New South Wales. NSW Biodiversity Strategy. NSW National Parks and Wildlife Service, Sydney.
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.
Kerr M, Jowett M, Robson D (2003) Reconstructed Distribution and Extent of Native Vegetation within the Lower Macquarie-Castlereagh Region. NSW National Parks and Wildlife Service, Dubbo.
Moree Regional Vegetation Committee (2002) Draft Moree Regional Vegetation Management Plan Version 8.0 May 13th, 2002. DLWC: Sydney
Peasley B, Walsh A (2001) Mapping Vegetation Landscapes of the Moree Shire. Unpublished NHT Report, Department of Land and Water Conservation, Inverell.
Sawtell R, Miller K (2001) Draft Vegetation mapping, Western Division Walgett Shire and Brewarrina Shire. DLWC: Inverell.
Sivertsen D, Metcalfe L (2001) Northern Wheatbelt vegetation mapping. Unpublished 1:250,000 scale vegetation maps and vegetation descriptions covering northern NSW Wheatbelt. NSW NPWS: Hurstville.
Skully L (2003) Relationships between vegetation clearance and the introduction of legislation in the Nyngan region, central western NSW. Ecological Management and Restoration 4: 150-153.
Thackaway R, Creswell ID (1995) (eds) 'An interim biogeographic regionalisation of Australia: a framework for establishing the national system of reserves.' (Australian Nature Conservation Agency: Canberra).
White M (2001) Pre-clearing vegetation mapping of the Moree Shire. Unpublished report. NSW NPWS: Hurstville.
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