- Title
- Macrozamia flexuosa C. Moore (Zamiaceae): a review of distribution, habitat and conservation status of an endemic cycad from the Hunter Region of New South Wales
- Creator
- Bell, Stephen A. J.
- Relation
- Cunninghamia Vol. 19, p. 7-27
- Publisher Link
- http://dx.doi.org/10.7751/cunninghamia.2019.19.002
- Publisher
- National Herbarium of NSW
- Resource Type
- journal article
- Date
- 2019
- Description
- 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.
- Subject
- Macrozamia flexuosa; Hunter Valley; cycad; distribution; habitat; conservation status
- Identifier
- http://hdl.handle.net/1959.13/1405629
- Identifier
- uon:35528
- Identifier
- ISSN:0727-9620
- Language
- eng
- Full Text
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