Environmental determinants of a restricted cycad in central Australia, Macrozamia macdonnellii
Luke D. Preece A C , Angus W. Duguid B and David E. Albrecht BA School for Environmental Research, Charles Darwin University, Darwin, NT 0909, Australia.
B Alice Springs Herbarium, Alice Springs, NT 0871, Australia.
C Corresponding author. Email: lukepreece@gmail.com
Australian Journal of Botany 55(6) 601-607 https://doi.org/10.1071/BT06122
Submitted: 13 June 2006 Accepted: 6 March 2007 Published: 27 September 2007
Abstract
Macrozamia macdonnellii (F.Muell. ex miq.) 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.
Acknowledgements
L. Preece thanks his Honours supervisors Professor Mark Burgman and Dr Jane Elith of the University of Melbourne for guidance throughout this study. We thank Dr Noel Preece, Dr Glenn Edwards, Penny van Oosterzee and two anonymous reviewers for reviewing drafts of this paper. We also thank Nina Sawtell, Penny van Oosterzee and Dr Noel Preece for assisting in field work and colleagues in PWSNT for assisting in the present study. The field study was conducted through the Environmental Science group at the Botany Department, University of Melbourne, and Parks and Wildlife Service of the Northern Territory (PWSNT). Partial funding was provided by the G.A.M. Scott Research Award from the University of Melbourne. Prior species record data were provided by the NT Herbarium and PWSNT. We wish to further acknowledge CSIRO Sustainable Ecosystems and Parks and Wildlife Service of the Northern Territory in Alice Springs for their assistance with data, especially the Central Australian Ranges geographic information system (CARGIS).
Bowman D, Connors GT
(1996) Does low temperature cause the dominance of Acacia on the central Australian mountains? Evidence from a latitudinal gradient from 11 degrees to 26 degrees south in the Northern Territory, Australia. Journal of Biogeography 23, 245–256.
| Crossref | GoogleScholarGoogle Scholar |
Carpenter RJ
(1991) Macrozamia from the Early Tertiary of Tasmania and a study of the cuticles of extant species. Australian Systematic Botany 4, 433–444.
| Crossref | GoogleScholarGoogle Scholar |
Clarke PJ,
Latz PK, Albrecht DE
(2005) Long-term changes in semi-arid vegetation: invasion of an exotic perennial grass has larger effects than rainfall variability. Journal of Vegetation Science 16, 237–248.
| Crossref | GoogleScholarGoogle Scholar |
Grove TS,
O’Connell AM, Malajczuk N
(1980) Effects of fire on the growth, nutrient content and rate of nitrogen-fixation of the cycad Macrozamia riedlei. Australian Journal of Botany 28, 271–281.
| Crossref | GoogleScholarGoogle Scholar |
Jones DL,
Forster PI, Sharma IK
(2001) Revision of the Macrozamia miquelii (F.Muell.) A.DC (Zamiaceae section Macrozamia) group. Austobaileya 6(1), 67–97.
Keast A
(1959) Relict animals and plants of the Macdonnell Ranges. Australian Museum Magazine September, 81–86.
Latz PK
(1975) Notes on the relict palm Livistona mariae F.Muell. In central Australia. Transactions of the Royal Society of South Australia 99, 189–196.
Markgraf V,
McGlone M, Hope G
(1995) Neogene paleoenvironmental and paleoclimatic change in southern temperate ecosystems—a southern perspective. Trends in Ecology & Evolution 10, 143–147.
| Crossref | GoogleScholarGoogle Scholar |
Mound LA, Terry I
(2001) Thrips pollination of the central Australian cycad, Macrozamia macdonnellii (cycadales). International Journal of Plant Sciences 162, 147–154.
| Crossref | GoogleScholarGoogle Scholar |
Osborne R
(1999) Macrozamia macdonnellii. Encephalartos 59, 4–7.
Wintle B,
Elith J, Potts J
(2005) Fauna habitat modelling and mapping: a review and case study in the lower hunter central coast region of NSW. Austral Ecology 30, 719–738.
| Crossref | GoogleScholarGoogle Scholar |
Appendix 1. Data set for the field study
Available as an Accessory Publication on the web.
