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Environmental determinants of a restricted cycad in central Australia, Macrozamia macdonnellii

Preece, LD, Duguid, AW and Albrecht, DE (2007). Environmental determinants of a restricted cycad in central Australia, Macrozamia macdonnellii. Australian Journal of Botany,55(6):601-607.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 6 times in Scopus Article | Citations

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Title Environmental determinants of a restricted cycad in central Australia, Macrozamia macdonnellii
Author Preece, LD
Duguid, AW
Albrecht, DE
Journal Name Australian Journal of Botany
Publication Date 2007
Volume Number 55
Issue Number 6
ISSN 0067-1924   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-34848846884
Start Page 601
End Page 607
Total Pages 7
Place of Publication Collingwood, Vic, Australia
Publisher CSIRO Publishing
HERDC Category C1 - Journal Article (DEST)
Abstract Macrozamia macdonnellii (F.Muell. exmiq.) A.DC. (Zamiaceae) is a cycad restricted to the MacDonnell and surrounding ranges of central Australia. Although it is a conspicuous, iconic and reasonably abundant plant of these ranges, there has been little previous documentation of the factors that limit current distribution. The distribution is distinctively patchy with some observed preference for gullies, gorges and relatively shady slopes. Anecdotal evidence suggests this species may be a relict that had more widespread distributions during previous cooler and more mesic climates. In the present study field data were collected at 143 sites within 13 locations to test the environmental determinants of its current distribution, using logistic regression. A regression model was created to model the presence of M. macdonnellii in relation to the field-collected environmental variables and GIS software was used to create a second model for derived environmental variables and collated known locations of M. macdonnellii. Variables included in the models were selected by using Akaike's information criterion. The results suggest that M. macdonnellii is more likely to be present in environments that provide relatively low radiation (high shade), low maximum temperature, an optimum minimum temperature, steep slopes, high wetness, short distances to drainage lines and skeletal soils. Fire and rockiness indices were poor predictors of the presence of M. macdonnellii. Microclimate, determined by some of the variables, was found to be the primary limiting factor for the distribution of M. macdonnellii, which supports the possibility that this species is a climatic relict.
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