Outback Info (Private Seiten) © seit 1999

Boorabin National Park

Boorabin National Park protects 26,000 hectres of south-west vegetation growing on the eastern edge of its distribution and has a very rich suite of reptiles and small mammals.

The park lies along the Great Eastern Highway, halfway between Southern Cross and Coolgardie, in Western Australia's eastern Goldfields. It takes its name from the former Boorabbin townsite, a settlement established in 1898 to provide water for steam locomotives going to and from the Goldfields. Boorabbin is the Aboriginal name of a rock on the edge of the park.

The national park occupies a plateau between landscapes which drain both north and south (it was this circumstance that probably determined the route of the highway). The plateau carries a distinctive sandplain vegetation, growing in deep sands that were produced by erosion during the Tertiary period, some 50 million years ago. During the Tertiary there was a much wetter climate, and the ancient Archean land surface, called the Yilgarn Shield, was eroding at a faster rate than it is today. As a result, the sands are highly weathered, leached and deficient in nutrients.

In spite of this, the sandplain vegetation is surprisingly diverse. At Boorabbin the species-rich kwongan heaths of south-western Australia reach their easterly limit. John Beard, a botanist who conducted a major vegetation survey of Western Australia, recognised the distinctness of the plateau's vegetation by naming it the 'Boorabbin Plateau' vegetation system. Woodlands and mallee shrublands also occur in Boorabbin National Park, in association with either granite outcrops or the upper reaches of ancient drainage lines.

Wildflowers of Boorabin

Showy wildflowers which can be seen from the highway include flame grevillea (Grevillea eriostachya), grass leaf hakea (Hakea multilineata) and Roe's featherflower (Verticordia roei). The three semi-arid banksia species: swordfish banksia (Banksia elderiana), inland banksia (Banksia audax) and Lullfitz's banksia (Banksia lullfitzii) are all present in the kwongan, and the latter is a rare plant.

A proposal to extend Boorabbin National Park will considerably increase its size, and enable the park to fully represent the landscape sequence of the Boorabbin Plateau vegetation system. The extension includes large areas of eucalypt woodlands made up of at least ten eucalypt species. Nowhere else in the world are there such extensive semi-arid woodlands with trees achieving heights of up to 20 metres.

The woodlands have regrown after being cut for fuel, to power the Mundaring to Kalgoorlie water pipeline number eight pumping station, in the early 1900s. The most conspicuous are salmon gum (Eucalyptus salmonophloia), gimlet (E. salubris), redwood (E. transcontinentalis), red morrell (Eucalyptus longicornis) and ribbon-barked gum (E. sheathiana). These woodlands grow in broad valleys, the upper reaches of former drainage lines which have been filled in by alluvial (deposited by flowing water) or colluvial deposits (accumulation of unconsolidated material at the bottom of a cliff or slope). Unlike the Tertiary sandplains, these valleys are relatively 'new' environments (less than two million years old). As they are low in the landscape, they accumulate nutrients from elsewhere and develop relatively rich, reddish-brown loam soils, which support the larger woodlands.

The proposed extension to the park also includes numerous granite outcrops. The extra water run-off, and the coarse gritty loam soils, give rise to a distinctive fringing vegetation. Characteristic species are rock sheoak (Allocasuarina huegeliana), granite rock box (Eucalyptus petraea), Goldfields York gum (Eucalyptus loxophleba var. lissophloia), silver wattle (Acacia lasiocalyx) and roadside teatree (Leptospermum erubescens). One of the rarest plants in the Goldfields, granite rock poison (Gastrolobium graniticum) grows in small thickets, in association with some of these plants, at one outcrop within the proposed extension. Two granite outcrops within this area, Boondi and Woolgangie Rocks, were modified as water catchments to provide water to steam locomotives and have an interesting history.

Samphire and Salt Lakes

At the opposite end of the landscape spectrum are the salt lakes. The lake beds which are present today are the lowest points of a vast system of rivers which traversed the Yilgarn Shield during the Tertiary period, at the same time the ancient land surface was eroding to create the sandplains. The ancient rivers have now largely been filled in by the same processes which formed the broad valleys now occupied by eucalypt woodlands. The former course of the rivers can only be revealed now by detailed analysis of contours and vegetation patterns.

The lake floors contain low shrublands of samphire (Halosarcia halocnemoides), ball leaf bluebush (Maireana glomerifolia) and other species. The lake slopes and dunes are vegetated with rough-barked red mallee (Eucalyptus hypochlamydea), salt gum (Eucalyptus salicola) and mallee cypress pine (Callitris preissii subspecies verrucosa). Black oak (Casuarina pauper) and white cypress pine (Callitris glaucophylla) woodlands grow in gypsum soils. For such plants, the advantages of living low in the landscape in a moisture and nutrient accumulating environment, is partially offset by having to cope with highly saline or gypseous soils.

THINGS YOU NEED TO KNOW

Where is it?
About 70 km east of Southern Cross.

Travelling time:
 

What to do:
Bushwalking, nature study.

Facilities:
Boorabbin National Park has no facilities, although wild camping is permitted in appropriate areas.