Journal of the Royal Society of Western Australia, 87:63-79, 2004 
Vegetation classification and ordination of the central 
Hamersley Ranges, Western Australia 
E J B van Etten 1 & J E D Fox 2 
1 Centre for Ecosystem Management, School of Natural Sciences, Edith Cowan University, Joondalup WA 6027. 
IS! e.van_etten@ecu.edu.au 
2 Department of Environmental Biology, Curtin University of Technology, Box U1987, Perth WA 6845. 
£3 J.Fox@curtin.edu.au 
(Manuscript received August 2003; accepted June 2004) 
Abstract 
Vegetation studies of Australian mountainous deserts are limited. The Hamersley Ranges region 
of north-west Australia is such an environment. It comprises a series of ranges and other uplands 
which rise above an extensive plateau. Geologically the region is complex (bedrocks range from 
Archaean granites gneisses to Proterozoic sedimentary ironstones to Tertiary limestone to 
various colluvial and alluvial deposits). At 139 sites within the central portion of the Ranges, the 
cover, frequency and abundance of perennial plant species were measured. The data were used to 
construct a site dissimilarity matrix using the Bray-Curtis measure. Both hierarchical (flexible- 
UPGMA) and non-hierarchical (ALOC) classification procedures were used on this matrix to derive 
a vegetation classification consisting of 16 plant communities, 2 vegetation types and 8 sub-types. 
Each community is described in detail and contrasted in terms of floristics, life-forms, structure 
and indicator species. Ordination (using a hybrid form of multidimensional scaling) showed 
intergradation of communities in terms of species composition, although the lowland communities 
were found to be relatively distinct from the uplands and pediment slopes. A floristic gradient 
along the topographic profile from mountain/hill top to valley floor was identified in the 
ordination space and characterised in terms of dominant species. A differential profile constructed 
for such floristic gradient found that, spatially, the transition zones between communities varied in 
width and other characteristics. It is hoped that the classification scheme and the methodology 
developed here will serve as a foundation for the whole Hamersley Ranges region. 
Keywords: vegetation, plant communities, classification, arid climate, Pilbara, Hamersley Ranges 
Introduction 
Extensive areas of hot desert with mountainous terrain 
are found on all continents with the exception of 
Antarctica and Europe (Evenari et al. 1985). Plant 
communities and other vegetation types have been 
determined and described for a large number of such 
areas (Goodall & Perry 1981; Evenari et al. 1985). 
Although they have employed a variety of classification 
approaches, such studies have regularly demonstrated or 
described the distinctiveness of plant communities, both 
spatially and in terms of species composition. Such 
vegetation patterning has often been attributed to the 
distinctiveness of landforms in such regions (Ayyad 1981; 
Wierenga et al. 1987; Abbas et al 1991; Cowlishaw & 
Davies 1997). For instance, typical desert landforms, such 
as hill slopes, pediments, bajadas, playas and regs, are 
often reported as having characteristic plant communities 
with relatively sharp boundaries between communities. 
Other authors have shown that, although some 
landforms have characteristic communities and dominant 
species, measurable gradients in species composition 
occur in the landscape in response to environmental 
gradients linked to gradually decreasing slopes and/or 
© Royal Society of Western Australia 2004 
altitude (Ezcurra et al. 1987; Cornelius et al. 1991; 
Ghazanfar 1991; Parker 1991; Vetaas 1992; Patten & Ellis 
1995). This often results in broad transition zones 
between communities (i.e. ecoclines), especially along 
subdued slopes of the piedmont ("foot of the mountain") 
zone. Where vegetation studies have been regional rather 
than local in extent, various geological substrates and 
climatic gradients are likely to be encountered, which 
further complicates variation patterns. There are some 
reports of different communities on the same landform 
in response to different types of parent rocks (Danin & 
Orshan 1990; Ward et al. 1993), whilst others have 
reported geological control on vegetation to be secondary 
to landform (Parker 1991). 
Mountainous deserts cover about 12% of Australia's 
extensive arid zone (Mabutt 1977; Williams & Calaby 
1985). They are generally of much lower relief than 
mountainous deserts elsewhere, but tend to show the 
same broad pattern of landforms. Examples include the 
Macdonnell, Flinders, Central and Hamersley Ranges. 
The Hamersley Ranges cover an extensive area of 
approximately 60 000 km 2 within the arid, north-west of 
Australia (Fig 1). The Ranges consist of a series of east- 
west trending mountain ranges rising above an extensive 
plateau. Between the ranges are broad drainage systems. 
Previous vegetation studies of the Ranges are limited and 
comprise a regional delineation and mapping of 
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