Abstract Detail



Biogeography

Jobson, Peter C. [1].

Standing on a Red Rock scanning a Desert Sea: the biogeography of central Australia.

Contrary to what you would expect, the flora of central Australia is not poor in species number, but rather it consists of over 2300 species. This is due, in part, to the diverse landscape and soil types within this region. Sand dunes, claypans, salt lakes, gibber plains, river flood-outs, gorges, hills and mountain ranges all make up the landscape of central Australia. The main soil types are either sands or clays, but their sources are diverse – wind blown, alluvial, and erosion are obvious, but less so are those influenced by salt or derived from gypsum. The most speciose part of central Australia is the MacDonnell Ranges housing well over 1300 species, with the highest level of endemism as well as a refuge to species more often associated with wetter climates. In contrast, the Simpson Desert is quite poor in species with under 100 species recorded and possibly only one endemic. Some surprising facts emerge when you look at the genera and number of species. By far, wattles (Acacia) is the largest genus in the region with over 110 taxa, whereas the eucalypts (Eucalyptus) have 30 species and bloodwoods (Corymbia) just 17. Other groups well represented include Emu or Fuchsia Bush (Eremophila - 44 taxa); sidas (Sida - 43); goodenias (Goodenia - 41); and cassias (Senna - 27). The dominant plant families for the region include grasses (320+ taxa), daisies (184), peas (174), chenopods (146) and the hibiscus family s.lat. (136). Some of these families consist of well represented genera such as Eragrostis and Triodia (grasses), or Maireana, Atriplex and Sclerolaena (chenopods); whereas in the case of the daisies and peas, although there are a few genera that have numerous species, most genera are represented by one or two species. Absences also tell an interesting story: iconic genera such as Boronia, Banksia, and Leptospermum (Tea-Tree), and orchids are absent. Speciose groups such as the egg-and-bacon peas, bearded heaths (Leucopogon) and guinea flowers (Hibbertia) are often represented by one or two species. So, if the species one normally thinks of as iconically Australian are missing, but there are still large numbers of taxa present, what is the likely origin of the central Australian plants? The answer is a complex, three pronged one. The three prongs are: temperate origin, tropical origin, and refugia from a wetter time. These three patterns shall be discussed with possible processes postulated.


1 - Northern Territory Herbarium, Alice Springs, Department of Environment & Natural Resources, PO Box 1120, Alice Springs, Northern Territory, 0870, Australia

Keywords:
biogeography
Australia
desert.

Presentation Type: Oral Paper
Number:
Abstract ID:474
Candidate for Awards:None


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