Inland Grey Box Woodland in the Riverina, NSW South Western Slopes, Cobar Peneplain, Nandewar and Brigalow Belt South Bioregions - Determination to make a minor amendment to Part 3 of Schedule 1 of the Threatened Species Conservation 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. Inland Grey Box Woodland in the Riverina, NSW South Western Slopes, Cobar Peneplain, Nandewar and Brigalow Belt South Bioregions is the name given to the ecological community found on relatively fertile soils of the western slopes and plains of NSW in which Eucalyptus microcarpa (Inland Grey Box) is the most characteristic species. The community generally occurs where average rainfall is 375–800 mm pa (Moore 1953, Beadle 1981, Botanic Gardens Trust 2005) and the mean maximum annual temperature is 22–26^oC (Botanic Gardens Trust 2005). In NSW the community principally occurs within the Riverina and South West Slopes Bioregions and is also found in portions of the Cobar Peneplain, Nandewar and Brigalow Belt South Bioregions. Bioregions are defined in Thackway and Cresswell (1995).

2. Inland Grey Box Woodland includes those woodlands in which the most characteristic tree species – Eucalyptus microcarpa – is often found in association with Eucalyptus populnea subsp. bimbil (Bimbil Box), Callitris glaucophylla (White Cypress-pine), Brachychiton populneus (Kurrajong), Allocasuarina luehmannii (Buloke) or Eucalyptus melliodora (Yellow Box), and sometimes with Eucalyptus albens (White Box).

Shrubs are typically sparse or absent, although this component can be diverse and may be locally common, especially in drier western portions of the community (Prober and Thiele 2004). A variable ground layer of grass and herbaceous species is present at most sites. At severely disturbed sites the ground layer may be absent. The community generally occurs as an open woodland 15–25 m tall but in some locations the overstorey may be absent as a result of past clearing or thinning, leaving only an understorey. Beadle (1948) commented that in its pristine state the overstorey density of this community was sometimes high, approaching a forest structure in southern portions of its range.

3. Inland Grey Box Woodland is characterised by the following assemblage of species:

4. 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 very 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 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 fire intensity and 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. Further examples are provided below, but the full complement of species in the community is incompletely documented.

5. Inland Grey Box Woodland may be found in the local government areas of Albury, Berrigan, Bland, Blayney, Boorowa, Cabonne, Carrathool, Conargo, Coolamon, Cootamundra, Corowa, Cowra, Deniliquin, Dubbo, Forbes, Gilgandra, Greater Hume, Griffith, Gundagai, Gunnedah, Gwyder, Inverell, Jerilderie, Junee, Lachlan, Leeton, Liverpool Plains, Lockhart, Mid-western Regional, Murray, Murrumbidgee, Narrabri, Narrandera, Narromine, Parkes, Temora, Upper Lachlan, Urana, Wagga Wagga, Wakool, Warrumbungle, Weddin, Wellington and Young. Inland Grey Box Woodland may occur elsewhere in the nominated bioregions. Bioregions are defined in Thackway and Cresswell (1995).

6. In their detailed assessment of grassy box woodlands in central NSW, Prober and Thiele (2004) identified a correlation between Eucalyptus microcarpa communities and “soils of Tertiary and Quaternary alluvial (or occasionally colluvial or eluvial) origin, largely corresponding with the Red Brown Earths as described in Beadle (1948) and Moore (1953).” This ecological attribute helps distinguish between Inland Grey Box Woodlands and the White Box Yellow Box Blakely’s Red Gum Woodland which is listed as an Endangered Ecological Community. The latter community generally occurs further east and typically occupies a wide variety of alluvial and non-alluvial soils (Prober and Thiele 2004).

7. Gradients in floristic diversity found across Inland Grey Box Woodland are also related to climatic differences as rainfall declines to the west and temperature increases to the west and north. Inland Grey Box Woodland can, in some regions, be differentiated from Eucalyptus albens–E. melliodora communities by grass species. Themeda australis and Poa sieberiana characterise the latter community whereas Austrostipa scabra, Austrodanthonia spp. and Enteropogon spp. are more typically associated with Eucalyptus microcarpa, although disturbance weakens this correlation (Prober and Thiele 2004). Chenopods and other shrubs are more common in the western than eastern portions of Inland Grey Box Woodland, and diversity of canopy species decreases with latitude (Keith 2004)

8. Inland Grey Box Woodland includes several closely related associations. Both Beadle (1948) and Moore (1953) included the Eucalyptus microcarpa community within their ‘Tall Woodland Eucalyptus woollsiana’ associations. Specht et al. (1995) identified ‘T362: Eucalyptus microcarpa’ on western slopes of southern NSW which represents part of the nominated community. In the Riverina the community was identified by Porteners (1993) as ‘Map Unit 24: Grey Box Woodland’, and this name was continued in Todd (2003). White et al. (2002) identified a somewhat broader vegetation unit in the Riverina, typically dominated by Eucalyptus microcarpa, as ‘Temperate Plains Grassy Woodland’. Seddon et al. (2002) described ‘Community B: Grey Box–White Cypress-pine Woodland’ in the Little River Catchment. In the Forbes–Lake Cargelligo area, Sivertsen and Metcalfe (1995) described three ‘Box Woodlands’ (P3, P4 and F3) in which Eucalyptus microcarpa was a characteristic species along with E. populnea and Callitris glaucophylla. They later distinguished ‘P13 Grey Box Woodlands’ from two ‘Poplar Box Woodlands’ (P4 and P16) in their assessments north of the Lachlan River (Metcalfe et al. 2003). In the vicinity of Dubbo, Kerr et al. (2003) described the broad vegetation class of ‘Grey Box/Pilliga Box/Poplar Box woodland on undulating rises and flats,’ with Eucalyptus microcarpa becoming less prevalent to the north. On a statewide scale, Benson et al. (2006) described six communities as fitting within the definition of Inland Grey Box Woodland (ID76, ID80, ID81, ID82, ID110 and ID237). The nominated community belongs to ‘Floodplain Transition Woodlands’ vegetation class of Keith (2004) which also includes the Eucalyptus conica (Fuzzy Box) and E. pilligaensis (Pilliga Box) woodland communities where E. microcarpa rarely occurs.

9. Two woodland communities that are listed as Endangered Ecological Communities under the Threatened Species Conservation Act adjoin and intergrade with Inland Grey Box Woodland:

• Fuzzy Box on alluvials of the NSW South Western Slopes, Darling Riverine Plains and Brigalow Belt South Bioregions
• White Box Yellow Box Blakely’s Red Gum Woodland

Woodlands of Eucalyptus pilligaensis and E. populnea, and those of E. moluccana (Coastal Grey Box) in the Sydney Basin Bioregion are also related. Inland Grey Box Woodland can grade into inland riverine forests of Eucalyptus camaldulensis (River Red Gum) and E. largiflorens (Black Box) along inland rivers and floodplains. These later communities are not covered by this Determination.

10. Fauna species found in some stands of Inland Grey Box Woodland that are listed under the Threatened Species Conservation Act include:

• Aprasia parapulchella – Pink-tailed Legless Lizard
• Burhinus grallarius – Bush Stone-curlew
• Lathamus discolor – Swift Parrot
• Melithreptus gularis gularis – Black-chinned Honeyeater
• Neophema pulchella – Turquoise Parrot
• Ninox connivens – Barking Owl
• Petaurus norfolcensis – Squirrel Glider
• Phascogale tapoatafa – Brush-tailed Phascogale
• Polytelis swainsonii – Superb Parrot
• Pomatostomus temporalis temporalis – Grey-crowned Babbler
• Pyrrholaemus sagittata – Speckled Warbler
• Stagonopleura guttata – Diamond Firetail
• Vespadelus troughtoni – Eastern Cave Bat

Flora species found in some stands of Inland Grey Box Woodland that are listed under the Threatened Species Conservation Act include:

• Austrostipa wakoolica – A spear-grass
• Dichanthium setosum – Bluegrass
• Diuris tricolor (syn. D. sheaffiana) – Pine Donkey Orchid
• Swainsona sericea – Silky Swainson-pea

11. Grassy box woodlands of NSW were rapidly targeted for agriculture development and extensively cleared or degraded (Benson 1991) so that by 1948 few remnants existed and those were often degraded by grazing (Beadle 1948). Inland Grey Box Woodland has been greatly reduced in area, highly fragmented and greatly disturbed by clearing, cropping, grazing, introduction of exotic species and addition of fertiliser. Areal reductions of Inland Grey Box Woodland have been independently documented by several authors for regional portions of this community. For example, Austin et al. (2000) found the community had been reduced to 3% of its original extent in the central Lachlan region. Kerr et al. (2003) estimated that of 116 000 ha of a broader community (including some Eucalyptus pilligaensis and E. populnea woodland) in the vicinity of Dubbo, only 16% remains. In the Riverina and Cobar Peneplain Bioregions, Todd (2003) reported that 762000 ha of Inland Grey Box Woodland has been reduced by 97% to 20000 ha of remnants. Of the estimated 9600 ha of Grey Box–White Cypress-pine Woodland in the Little River Catchment, less than 250 ha (2%) remains (Seddon et al. 2002). On the basis of regional estimates, 67–92% of the pre-European extent of Inland Grey Box sub-communities have been cleared (Benson et al. 2006). A cumulative assessment of these regional values indicates an overall decline of 85% from 1532000 ha to 236000 ha. The various regional values and the cumulative estimate indicate a reduction of a least 70% in the geographic distribution. This large reduction of the community has occurred in the past 150 years and clearing continues to affect areas of the community. ‘Clearing of native vegetation’ is listed as a Key Threatening Process under the Threatened Species Conservation Act.

12. Some remnants of the community survive with trees partly or wholly removed. Conversely, often the remnants of the community survive with trees largely intact but with the shrub or ground layers degraded to varying degrees through grazing or pasture modification. Some species that are part of the community appear intolerant to heavy grazing by domestic stock and are confined to the least disturbed remnants (Prober and Thiele 2004). Remnants are subject to various processes of degradation that have led to a large reduction in ecological function including:

• Continuing small scale clearing for cropping, pasture improvement or other developments;
• Firewood cutting, increased livestock grazing, stubble burning, weed invasion, inappropriate fire regimes, soil disturbance and increased nutrient loads;
• Degradation of the landscape in which remnants occur including soil acidification, salinisation, extensive erosion scalding and loss of connectivity.

A number of Key Threatening Processes listed under the Threatened Species Conservation Act adversely affect areas of Inland Grey Box Woodland. These include:

• Removal of dead wood and dead trees
• Invasion of native plant communities by exotic perennial grasses
• Predation by the European Red Fox, Vulpes vulpes
• Predation by the Feral Cat, Felis catus
• Competition from feral honey bees, Apis mellifera
• Competition and grazing by the feral European Rabbit, Oryctolagus cuniculus

13. Some remnants are highly degraded, with weedy understoreys and only a few hardy natives remaining. A number of less degraded remnants have survived in Travelling Stock Routes, cemeteries and reserves. Understorey species composition may differ markedly between these sites because of past and present management practices. In some instances intentional introduction of non-indigenous species has occurred in these reserves. Some remnants of the community that consist of only an intact overstorey or an intact understorey still have high conservation value due to the flora and fauna they support. Other sites may be important examples of specific faunal habitat, have significant occurrences of particular species, comprise portions of vegetation corridors or have the potential for rehabilitation. The conservation value of remnants may be independent of remnant size. Disturbed remnants are considered to form part of the community including remnants where the understorey, overstorey or both would, under appropriate management, respond to assisted natural regeneration from the soil seed bank.

14. The community is poorly represented in conservation reserves and, even then, is almost invariably found in small patches left after surrounding fertile land has been cleared for agriculture. Examples of Inland Grey Box Woodland are found in Buckingbong Flora Reserve (FR), Cocopara National Park (NP), Cocopara Nature Reserve (NR), Coolbaggie NR, Gubbata NR, Nangar NP, Pucawan NR, Round Hill NR, Strahorn FR, The Rock NR, Warrumbungle NP, Weddin Mountains NP, Wiesners Swamp NR, Wilbertroy FR, Woggoon NR and Wongarbon NR.

15. Inland Grey Box Woodland in the Riverina, NSW South Western Slopes, Cobar Peneplain, Nandewar and Brigalow Belt South Bioregions 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 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 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

(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

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Beadle NCW (1948) ‘The vegetation and pastures of western New South Wales with special reference to soil erosion.’ Soil Conservation Service, Sydney.

Beadle NCW (1981) ‘The vegetation of Australia.’ (Cambridge University Press: Cambridge)

Benson J (1991) The effect of 200 years of European settlement on the vegetation and flora of New South Wales. Cunninghamia 2, 343–370.

Benson JS, Allen, CB, Togher C, Lemmon J (2006) New South Wales Vegetation Classification and Assessment. Part 1 Plant communities of the NSW western plains. Cunninghamia 9, 383-450.

Botanic Gardens Trust (2006) Grey box Eucalyptus microcarpa, in PlantNET (version 2). Accessed on 20 October 2006.

Keith D (2004) ‘Ocean Shores to Desert Dunes: The Native Vegetation of New South Wales and the ACT.’ (NSW Department of Environment and Conservation: Hurstville)

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