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Hunter Valley Weeping Myall Woodland is listed as a Critically Endangered Ecological Community (CEEC) under both the New South Wales Threatened Species Conservation (TSC) Act 1995 and the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act 1999. Uncertainty regarding the provenance of Weeping Myall (Acacia pendula) in the Hunter has led to questioning of the place of Hunter Valley Weeping Myall Woodland CEEC in State and Commonwealth legislation. A recent publication has endorsed its legislative listing, largely based on the co-association of Weeping Myall with a range of other semi-arid species in some parts of the Hunter Valley. We counter this argument and show that the semi-arid species present in low rainfall areas on Permian sediments of the Hunter Valley floor are in fact more widespread than previously documented. Through examination of distributional records, we demonstrate that these species display no fidelity to purported Hunter Valley Weeping Myall Woodland, but instead occur in a range of other vegetation communities across much of the central and upper Hunter Valley. Habitat suitability modelling undertaken for Acacia pendula shows there to be nearly 900 times the 200 ha of pre-European extent, or 20 times the area of occupancy previously estimated for this community. We also revisit an earlier ordination analysis which showed a divergence in sample data potentially representative of Hunter Valley Weeping Myall Woodland. We add new samples and provide a revised classification of the purported community, which shows that sample plots from two forms of Hunter Valley Weeping Myall Woodland are floristically indistinguishable from comparative data in 20-25 year old mining rehabilitation forests of Eucalyptus cladocalyx, and native grasslands derived predominantly from landscapes of Eucalyptus crebra and Eucalyptus moluccana. Relevant legislation requires any threatened community to be identifiable based on a particular species assemblage and its area of occupancy. We question whether Hunter Valley Weeping Myall Woodland is recognisable with and without the presence of Acacia pendula. We argue that the identification of Hunter Valley Weeping Myall Woodland is unachievable without the visual cue of Acacia pendula, and note that for some time regional botanists have used this species’ presence as a de facto diagnostic tool to identify this community; in fact, there are no examples of the community having been identified as such in the absence of Acacia pendula. Finally, following from our ordination results, and the presence of key diagnostic species within more widespread grassy woodlands and derived native grasslands, we suggest that 200 years of anthropogenic disturbance across the Hunter Valley has sufficiently masked any distributional pattern of western semi-arid species that might have once occurred. We contend that there is little value in conserving a purported community that cannot be confidently delineated in numerical classifications, lacks a consistent and diagnostic suite of characteristic species, and for which there is uncertainty over the origins of its dominant, flagship species, Acacia pendula.
Rare or threatened vascular plant species of Wollemi National Park, central eastern New South Wales
(2008)
Wollemi National Park (c. 32o 20’– 33o 30’S, 150o– 151oE), approximately 100 km north-west of Sydney, conserves over 500 000 ha of the Triassic sandstone environments of the Central Coast and Tablelands of New South Wales, and occupies approximately 25% of the Sydney Basin biogeographical region. 94 taxa of conservation significance have been recorded and Wollemi is recognised as an important reservoir of rare and uncommon plant taxa, conserving more than 20% of all listed threatened species for the Central Coast, Central Tablelands and Central Western Slopes botanical divisions. For a land area occupying only 0.05% of these divisions, Wollemi is of paramount importance in regional conservation. Surveys within Wollemi National Park over the last decade have recorded several new populations of significant vascular plant species, including some sizeable range extensions. This paper summarises the current status of all rare or threatened taxa, describes habitat and associated species for many of these and proposes IUCN (2001) codes for all, as well as suggesting revisions to current conservation risk codes for some species. For Wollemi National Park 37 species are currently listed as Endangered (15 species) or Vulnerable (22 species) under the New South Wales Threatened Species Conservation Act 1995. An additional 50 species are currently listed as nationally rare under the Briggs and Leigh (1996) classification, or have been suggested as such by various workers. Seven species are awaiting further taxonomic investigation, including Eucalyptus sp. ‘Howes Swamp Creek’ (Doherty 26), known from a single location within the park, and Pultenaea sp. (Olinda) from Dunns Swamp – both these species remain undescribed, but are listed as endangered species. After applying IUCN criteria to the 94 taxa, 2 are considered Critically Endangered; 11 are considered Endangered; 23 are considered Vulnerable; 3 are considered Near Threatened; 19 are considered Data Deficient; and 36 are considered of Least Concern. It is likely that additional highly restricted plant taxa await discovery in remote locations.
As a consequence of vegetation survey carried out in sandstone environments of the upper Hunter Valley over recent years, a number of new populations of significant plant species have been recorded. The opportunity is taken here to document some of these finds, and also to suggest some revisions to the current conservation risk codes. Twenty-three species are discussed: Acacia bulgaensis, Angophora euryphylla, Callitris rhomboidea, Banksia penicillata, Cynanchum elegans, Eucalyptus aenea, Eucalyptus dealbata, Eucalyptus fergusonii subsp. dorsiventralis, Eucalyptus nubila, Eucalyptus prominula, Gonocarpus longifolius, Grevillea johnsonii, Grevillea montana, Melaleuca groveana, Pomaderris bodalla, Pomaderris brunnea, Pomaderris precaria, Pomaderris queenslandica, Pomaderris reperta, Pomaderris sericea, Prostanthera cryptandroides subsp. cryptandroides, Prostanthera hindii, and Rulingia procumbens. Voucher specimens have been lodged for new populations of all taxa (except some populations of Cynanchum elegans) at State herbaria.
Habitat details and population sizes are provided for six populations of the rare leafless saprophytic terrestrial orchid Cryptostylis hunteriana Nichols (family Orchidaceae) from the Wyong-southern Lake Macquarie area of New South Wales. The extent of potential habitat based on known sites on the Central Coast is examined in a regional context, and annual targeted surveys in similar habitat are suggested. Apart from a population of unknown size in Ku-ring-gai Chase National Park, no populations of Cryptostylis hunteriana are at present within conservation reserves on the Central Coast. The paucity of records in the region suggests that any information about ecology or habitat will be beneficial to conservation and management. Adoption of a landscape approach may be the most appropriate avenue to ensure long term conservation. Due to the limited records, the poor representation in reserves and the species' cryptic nature, assessment and survey of all known populations of Cryptostylis hunteriana in New South Wales should be undertaken, prior to a review of its current conservation status.
Angophora inopina is a vulnerable tree species occurring principally in Wyong and Lake Macquarie local government areas on the Central Coast, with disjunct populations as far north as Bulahdelah on the North Coast of NSW. The largest and most intact stands occur within the Wyee-Morisset areas although even here significant fragmentation is evident. North of Toronto, there are small and scattered residual populations as far as Barnsley near West Wallsend in Lake Macquarie. A total area of occupied habitat of approximately 1500 ha is estimated.
Cluster analysis of floristic information showed that Angophora inopina occurs within three broad habitat types within the Central Coast bioregion, centred mainly on the Gorokan, Doyalson and Wyong soil landscapes. Hybrid forms of the species also occur on the Cockle Creek landscape in northern Lake Macquarie. Most stands are evident within open woodland/ forest vegetation where Eucalyptus haemastoma, Corymbia gummifera, and Eucalyptus capitellata dominate with Angophora inopina. Other populations occur in wet heath, and swamp woodland environments where sedge species are characteristic.
Conservation of Angophora inopina will be most effectively and efficiently achieved if ecological processes that operate across the landscape are maintained. Processes such as fragmentation, altered fire regimes or invasion of habitat by exotic species must be managed in the long-term. These are all significant threats to this species, and will best be effectively managed in the larger remnants in a landscape approach. Such threats are generally associated with urban and agricultural expansion in the area, and these are therefore the most pressing issues to be managed.
Multivariate analysis and non-metric multidimensional scaling have been used to compare the floristic composition of vegetation dominated by Spotted Gum, Corymbia maculata, and Grey Ironbark, Eucalyptus paniculata, from the Pittwater and Gosford local government areas, and elsewhere on the Central Coast of New South Wales. When placed within a regional context, vegetation from both local government areas is strongly related, and is sufficiently distinct (at 30% similarity) from other areas of Spotted Gum-Ironbark vegetation within the region to warrant their collective consideration as Pittwater Spotted Gum Forest (PSGF), an Endangered Ecological Community in New South Wales. Within Pittwater local government area, two forms of PSGF are present: a dryer, more widespread form present on ridges and slopes, and a moister form with strong littoral rainforest affinities confined to gullies. Gosford local government area supports only the dryer form. Extant and pre-1750 mapping of PSGF from both local government areas (excluding Ku-ring-gai Chase National Park) shows a total extant distribution of 227 ha, and since 1750 an estimated loss of 727 ha (76%) from the original 954 ha. PSGF is present in two secure conservation reserves: Ku-ring-gai Chase National Park (~40 ha, Thomas & Benson 1985) and Bouddi National Park (~30 ha, Bell 2009), totaling ~ 70 ha. Despite this, much of the extant distribution lies at the reserve-urban interface, and is subject to ongoing threats of regular low-intensity fire, unmitigated clearing and weed invasion.
A vegetation survey was undertaken within Columbey National Park (32° 35’S, 151° 44’E) near Clarence Town in the lower Hunter Valley of New South Wales. Multivariate cluster analysis and non-metric multi-dimensional scaling were carried out on plot-based data to classify the vegetation into twelve native communities (one plantation), and each compared with a larger regional dataset. A vegetation map was also prepared, based heavily on extensive ground-data supplemented with aerial photographic interpretation. Although small in size, this reserve conserves good examples of the endangered Lower Hunter Spotted Gum-Ironbark Forest (475 ha) and River-Flat Eucalypt Forest on Coastal Floodplains (124 ha), together with a small parcel of Hunter Lowlands Redgum Forest (3.7 ha). Collectively, these Endangered Ecological Communities occupy approximately 70% of the 870 ha reserve. Small populations of the threatened and previously unreserved orchid, Pterostylis chaetophora are present in the reserve, together with the Endangered Corybas dowlingii and the regionally significant cycad, Macrozamia flexuosa. An historical record of Eucalyptus glaucina could not be substantiated during the current survey, and may have been recorded in error. A total of 349 vascular plant taxa were recorded, including 25 weed species. The vegetation present within Columbey National Park bears strong resemblance to that in the Cessnock region of the Hunter Valley (Bell 2004; DECC 2008), a feature attributed to similar rainfall and soil types. Vegetation communities common between the two areas include Lower Hunter Spotted Gum – Ironbark Forest, Red Ironbark Scrub-Forest, Paperbark Soak Forest, Floodplain Redgum-Box Forest and Gully Rainforest. Unlike the Cessnock area, however, Columbey has not been subject to illegal rubbish dumping to any great degree.
Little research has been undertaken on the conservation value of natural and derived native grasslands within the Hunter Valley region of New South Wales. In part, this is due to a lack of rigorous survey and classification of grassland habitats, but also because of the ease with which past studies have deferred to the concept of 'derived grasslands' to describe grassland areas. Given the extent of European occupation of the Hunter Valley over the past 200 years, all grasslands have been impacted upon in one way or another by agricultural activities, and hence all can be considered 'derived'. For one site in the upper Hunter Valley, classification and mapping of grasslands was undertaken using data collected over three Spring seasons from 2009 to 2011, encompassing over 1,000 ha of derived grassland habitat within a wider mosaic of forest and woodland. Numerical classification of 168 sampling plots (each 0.01ha in size) delineated 17 floristic groups (16 communities, one with two sub-communities). Based on the composition of component taxa, 8 of these can be considered primarily of exotic origin, while the remaining 9 are predominantly native. All grasslands have been shaped by past agricultural activities, and all have been collectively referred to previously as derived grasslands. Plant species of significance within the grasslands include the threatened terrestrial orchids Diuris tricolor and Prasophyllum petilum, the threatened forbs Swainsona recta and Thesium australe, and the rare but localised grass Bothriochloa biloba. An additional 19 taxa occur at or extend known distributional limits. The lack of an appropriate existing framework with which to assign conservation value to grasslands in the Hunter complicates any assessment of significance. However, considerable diversity is present within grasslands collectively referred to as 'derived', and effort should be applied in future studies to elucidate community patterns more satisfactorily. Within State and Federal threatened species legislation, there are 30 grassland or derived grassland communities, but only one of these (White Box - Yellow Box – Blakely's Red Gum Grassy Woodland and Derived Native Grassland: EPBC Act) potentially include the grasslands under study here.
Acacia pendula, Weeping Myall, (family Fabaceae) is the most legislatively protected plant species in the New South Wales Hunter Valley. Under the NSW Threatened Species Conservation Act 1995 it is listed as an Endangered Population (in the Hunter Valley) and as a component of two Endangered Ecological Communities (one in the Hunter, one elsewhere in NSW); it is also listed as a Critically Endangered Ecological Community (in the Hunter Valley) on the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and listed as threatened in three other eastern Australian States.
To ascertain the likely original distribution of stands of Acacia pendula in the Hunter Valley, this paper examines the writings of early Australian explorers, herbarium and database records, and the species habitat attributes across NSW. None of the journals examined, including those of botanist/explorer Allan Cunningham (who originally collected Acacia pendula from the Lachlan River in 1817), Thomas Mitchell or Ludwig Leichhardt, make note of the species for the Hunter Valley. Several explorers do, however, record Acacia pendula regularly (>100 times) across other parts of NSW, Queensland, and South Australia.
Historical herbarium and database records show a paucity of records from the Hunter prior to the year 2000, after which a 37-fold increase in observations since 1951 is apparent. For the first 128 years of botanical exploration (1823 to 1951), there are no validated collections or records of Acacia pendula from the Hunter Valley. The single exception is a specimen collected by Cunningham from 1825 (lodged at Kew, UK), purported to be from ‘Hunters River’, but which is morphologically different to other collections of Acacia pendula from that time. There is some uncertainty over the origins of this specimen.
Analysis of habitats supporting Acacia pendula in NSW outside of the Hunter show them to differ significantly in geological age, soil type, rainfall and elevation from those in the Hunter.
Collectively, these findings provide a strong circumstantial case that Acacia pendula was absent from the Hunter at the time of European settlement; this has important implications for the conservation and management of Hunter stands. Rather than being a threatened species in the Hunter Valley, it is postulated that Acacia pendula has been intentionally and/or accidentally introduced to the region, and may now be imposing a new and emerging threat to the endangered grassy woodlands and forests there. There is now an urgent need for genetic studies to clarify the origins of the current Hunter Valley stands, and to define the taxonomic limits of Acacia pendula and its close relatives.
A review has been undertaken of herbarium records, point location and full floristic data to assess the distribution, habitat and conservation status of Macrozamia flexuosa (Zamiaceae), a rare cycad endemic to the Hunter Region of New South Wales. Spatial analysis of all records (n=588) showed that the species is most prevalent on Permian-aged sediments but also occurs on older Carboniferous sediments and younger Triassic Narrabeen and Quaternary substrates. Point records intersect with a wide range of annual average rainfall bands (<700 to 1400 mm/yr), suggesting either that the species is tolerant of a variety of soil moisture gradients, or that current distribution may be representative of a differing climatic environment. Interpolation of database records (n=397) across 175,000 hectares of high-resolution vegetation mapping showed Macrozamia flexuosa to most frequently occur within the Lower Hunter Spotted Gum-Ironbark Forest (41%), followed by Kurri Sands Swamp Woodland (16%), Coastal Foothills Spotted Gum-Ironbark Forest (15%) and Coastal Plains Smooth-barked Apple Woodland (13%). Numerical analysis of full floristic plot data (n=86) largely supported these results, with the addition of Hunter Valley Moist Forest to these four regional communities. A revised assessment of the conservation significance of Macrozamia flexuosa suggests that the existing conservation risk code of 2K be amended to 3RCa (distributional range >100km; rare but not immediately threatened; adequately conserved in at least 14 conservation reserves). An extent of occurrence of 6,319 km2 and an area of occupancy of 696 km2 have been determined for the species, and an estimated population size of between 1,740,000 and 43,500,000 individuals has been calculated. Under IUCN threat criteria, a code of NT (Near Threatened) is here considered appropriate for Macrozamia flexuosa, recognising uncertainties applicable to the assessment of Criteria A and B. It is noted, however, that Macrozamia flexuosa may currently be in slow decline due to as yet unknown limitations in flowering, pollination and/or dispersal mechanisms over a long period of time (many decades), with the longevity of individual specimens confounding any observable trends. A lack of demographic data relevant to these life traits limits comprehensive assessment, and further research to address these data gaps is recommended.