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

  • 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.

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Metadaten
Author:Stephen A. J. Bell
URN:urn:nbn:de:hebis:30:3-583281
DOI:https://doi.org/10.7751/cunninghamia.2019.19.002
ISSN:0727- 9620
ISSN:2200 - 405X
Parent Title (English):Cunninghamia : a journal of plant ecology for eastern Australia
Document Type:Article
Language:English
Year of Completion:2019
Year of first Publication:2019
Publishing Institution:Universit├Ątsbibliothek Johann Christian Senckenberg
Release Date:2021/02/10
Tag:Hunter Valley; Macrozamia flexuosa; conservation status; cycad; distribution; habitat
Volume:19
Page Number:21
First Page:7
Last Page:27
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 58 Pflanzen (Botanik) / 580 Pflanzen (Botanik)
Sammlungen:Sammlung Biologie / Sondersammelgebiets-Volltexte
Zeitschriften / Jahresberichte:Cunninghamia : A Journal of Plant Ecology for Eastern Australia / Cunninghamia : A Journal of Plant Ecology for Eastern Australia, Volume 19 (2019)
:urn:nbn:de:hebis:30:3-514446
Licence (German):License LogoDeutsches Urheberrecht