Journal of the Royal Society of Western Australia, 87:19-28, 2004 
Vegetation and flora of a diverse upland remnant of the Western Australian 
wheatbelt (Nature Reserve A21064). 
F J Obbens 1 & L W Sage 2 
1 C/o Western Australian Herbarium, Department of Conservation and Land Management 
Locked Bag 104, Bentley Delivery Centre WA 6983 
O bushtech@wal .quik.com.au 
2 Swan Coastal District, Department of Conservation and Land Management, 
5 Dundebar Road, Wanneroo WA 6065 
CE3 leighs@calm.wa.gov.au 
Abstract 
In the Western Australian wheatbelt, small intact remnants of bushland can contribute 
significantly to overall biodiversity. Our comprehensive vascular flora survey of Nature Reserve 
A21064, a reserve of 110 hectares near the town of Arthur River, has highlighted this aspect. 
Comprehensive surveys of selective wheatbelt reserves provide benchmarks to help us better 
understand the flora and vegetation in this highly cleared and fragmented agricultural landscape. 
In the diverse flora of this relatively undisturbed upland remnant ten distinct plant communities 
encompassing heaths, herbfields, mallee and woodlands can be recognised. The survey identified 
323 vascular plant taxa including one rare species, seven priority species and a number of taxa of 
special interest recorded from 51 families. Weeds accounted for 22 species (6.8% of total flora), 
however, the extent of invasion is relatively low. 
Keywords: Vegetation and flora survey, upland remnant, biodiversity, wheatbelt woodlands 
(Manuscript received January 2003; accepted December 2003) 
Introduction 
Nature Reserve A21064 is an upland bush remnant of 
high conservation value ( i.e . "A" class nature reserve) 
with a diverse flora (see species list in Appendix 1). It is 
approximately 110 ha in area and is located about 190 km 
directly south-east of Perth near the town of Arthur 
River, Western Australia (Fig 1). The district has a dry 
Mediterranean type climate with very warm, dry 
summers and cool, wet winters. Average annual rainfall 
for the reserve is about 470 mm, which is typical of the 
wetter western (inner) margins of the wheatbelt. 
The reserve is situated at the end of an eroded and 
generally flattened ridgeline and its upper slopes; the 
ridge is the watershed between Mailling Gully to the 
south and a smaller unnamed tributary to the north. 
These streams eventually drain into the Arthur River 
about 7 km west of the reserve. The Arthur River and 
adjacent Norcott Plains also run north of the reserve, 
about 3 km away. The reserve is a small L-shaped 
remnant with the longest east-west boundary (1.9 km) 
roughly parallel to the ridgeline/plateau. The north- 
south arm of the L measures approximately 1.2 km (Fig 
2). Slopes descend gently off the ridgeline and the 
predominant aspect is north or north-west. A pattern of 
low undulating hills/ridges with interspersed small 
valleys and/or plains is typical locally and is a familiar 
topography for much of this inner wheatbelt region. 
Granite outcrops and/or lateritic breakaways are often 
found on the upper slopes or hilltops. Historically, many 
upland areas were not cleared for cropping because of 
© Royal Society of Western Australia 2004 
Figure 1. Location of A21064 Nature Reserve, near Arthur River, 
in the south-west of Western Australia; also shown are 100 mm 
rainfall isohyets. 
the rougher topography. Also upland areas were 
generally abundant in the poisonous Gastrolobium species 
that killed domestic stock. Alternatively, some were left 
as 'shade and shelter belts'. Today, very few of these 
upland remnants have survived completely intact. 
Significant numbers have had a reduction in tree cover 
due to past logging ( e.g . for timber and fence posts), 
insect pests, disease etc, and this has occurred in a 
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