Cunninghamia : A Journal of Plant Ecology for Eastern Australia, Volume 19 (2019)
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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.
A review and update to the list of significant vascular plant taxa has been made for the c. 500 000 ha Wollemi National Park, approximately 100 km north-west of Sydney, New South Wales. A previous assessment in 2008 revealed the presence of 94 significant taxa, including 15 listed as Endangered and 22 listed as Vulnerable in NSW Threatened Species legislation. New field surveys, coupled with analysis of observation (NSW OEH Bionet Atlas) and specimen collection (Australasian Virtual Herbarium) databases, has added a further 16 significant taxa to the reserve total, elevating it to 110. A revised assessment of the total threatened flora, as listed on the NSW Biodiversity Conservation Act 2016, shows there to be 1 Critically Endangered, 19 Endangered, 26 Vulnerable taxa and 2 Endangered Populations. For Commonwealth listed taxa under the Environment Protection and Biodiversity Conservation Act 1999, there are 1 Critically Endangered, 9 Endangered and 23 Vulnerable taxa. Sixty-one taxa are currently unrepresented within either legislation and may be considered rare, 8 taxa remain scientifically undescribed (one addition in this revision, Pultenaea 'monticola' Mt Irvine), while updated names are provided for two taxa now formally described (Eucalyptus expressa and Prostanthera stenophylla). Following assessment of all newly added taxa against IUCN criteria, one currently unlisted species (Hibbertia coloensis) qualifies as Critically Endangered, while a second (Bertya linearifolia) qualifies as Endangered. Discussion is also provided on six taxa where database records show them to be present within Wollemi, but are here excluded following closer examination.