Associations...
Euclyptus microcarpa
(grey box) open forest
Euclyptus microcarpa (grey box) woodland
E. microcarpa (grey box) / Allocasuarina
verticillata (drooping she-oak) low woodland
Eucalyptus leucoxylon (SA blue gum) woodland
Eucalyptus camaldulensis (red gum) woodland
(riverflat)
Olearia ramulosa (daisy bush) / A verticillata
(drooping she-oak) tall shrubland
Grassland / herbland
Bare ground
Tree plantings
Prior to European settlement, most of the land comprising the park would have carried a
typical Eucalyptus microcarpa (grey box) open woodland / open forest association and
E.
camaldulensis (red gum) would have dominated the watercourses.
Although the park still exhibits a range of indigenous species, a history of grazing,
timbercutting and cropping has resulted in modification of virtually all of the native
vegetation. Since the cessation of grazing in 1966, considerable regeneration of
Eucalyptus and Allocasuarina species has occurred.
Unfortunately, the absence of grazing has also allowed the establishment of undesirable
species such as:
Today, several vegetation associations can be delineated in the park, some of which
obviously result from degradation of indigenous associations.
In delineating the boundaries of the associations shown above, no
quantitative data were obtained, and decisions were based on subjective assessment of
aerial photography.
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Euclyptus microcarpa (grey box)
open forest
This association is the most similar to the open forest which must have originally
covered much of the park area. However, almost all is coppice regrowth regenerating after
tlmbercutting operations between 1936 and 1949, and as a result, trees are multi-stemmed
and of uniform age.
The understorey is variable, although much remains in good condition with relatively
few exotic species present. Prominent species are Acacia pycantha (golden
wattle) and
Acacia paradoxa (kangaroo thorn) which form dense thickets in moist gullies; and
Olearia ramulosa. The major introduced species are Sparaxis species and
scattered South African daisy (Senecio pterophorus).
The occurrence of this formation in the park is limited to the Craigburn
addition where it is the major vegetation type. This area is a valuable addition to
the park of an association which is not well conserved and of which there are
increasingly few intact examples.
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Euclyptus microcarpa (grey
Box) woodland
This association is largely confined to the less steep slopes in the
park and includes areas which would once have supported an open forest association.
Other than in the Craigburn addition, this association is
dominated by well-spaced, overmature E. microcarpa trees. In the Craigburn addition, trees are largely coppice regrowth.
The understorey is variable, some areas being dominated by dense regrowth of Eucalyptus
with scattered Acacia pycantha. Other areas are variously dominated by A.
paradoxa, Allocasuarina
verticillata, Dodonaea viscosa, and in the western
section of the park by Olea europaea (European
olive) and a variety of largely introduced grasses.
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Eucalyptus microcarpa (grey box) /
Allocasuarina
verticillata (drooping she-oak) low woodland
On steep slopes the E microcarpa woodland
association is replaced by a low woodland of A. verticillata and E. microcarpa over an understorey dominated by one or several of the following species: paradoxa
Oxalis pes-caprae
(soursob) frequently dominates the ground layer, particularly
on the lover slopes.
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Eucalyptus leucoxylon (SA
blue gum) woodland
Confined to two small areas with south-easterly aspects, this formation
consists of well-spaced, overmature E. leucoxylon over a grassland / herbland largely
dominated by introduced species. Dense groves of young European
olives dominate all areas
under the Eucalyptus.
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Eucalyptus camaldulensis (red gum)
woodland
(riverflat)
This association is confined to the riverflats adjacent to the Sturt River and is
dominated by scattered large E. camaldulensis
(river red gum).
In recent years, mainly since sheep were removed in the late 1960s, numerous
Fraxinus rotundifolia ssp.
rotundifolia (desert ash), Salix spp. (willows), Ficus carica (common
fig) and Crataegus
monogyna (hawthorn) have grown to form a variable lower tree strata.
Groundcover in this association is varied, Paspalum distichum
(salt-water couch-grass)
dominates much of the waterland interface with Typha species
(bulrush) and Phragmites
australis (common reed) dominating shallow water areas. Several sedge arid rush species,
particularly Cyperus vaginatus, are prominent in damp localities. Introduced species,
notably Oxalis pes-caprae
(soursob), form the dominant groundcover on the riverflats
above the flood level.
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Olearia ramulosa (daisy bush) /
Allocasuarina verticillata (drooping she-oak) tall shrubland
This association is confined to a limited area with a southerly aspect below
The Boulevard. One of the most densely vegetated areas in the park, this association in places
approaches a closed shrubland. Typically the area is dominated by large Olearia ramulosa
with scattered Acacia pycnantha and Dodonaea
viscosa, which are
locally common in small areas. Allocasuarina verticillata and Xanthorrhoea
quadrangulata dominate areas of shallow soil along the top of the tillite cliffs which
mark the lower limit of this association.
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Grassland / Herbland
In terms of area covered, this is the major vegetation form in Sturt Gorge Recreation
Park. Its occurrence is largely limited to the western half of
the park, although a small area occurs in the Craigburn
addition, probably as a result of clearing for crop production.
In the western section, apart from occasional large eucalypts, principally along
creeklines, the native overstorey has been entirely removed as a result of grazing
pressure, and introduced herbaceous species have become dominant.
A great variety or introduced species are present including:
The most abundant native grasses are Enneapogon nigricans and Themeda
australis.
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Bare ground
Before the introduction of introduced
grasses, bare patches of ground were common in the poor shallow soils of
many parts of the gorge. and were often home to mosses and lichens (ehat
spots in the image below).
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Tree Plantings
In the period between 1975 and 1978, approximately 4000 trees and shrubs were planted
by the Bellevue Heights and Eden Hills Community Association Inc under the supervision of
the National Parks and Wildlife Service staff. The area planted was largely restricted to
the upper slopes of the southern and western ends of the park and below The Boulevard,
Bellevue Heights. The species planted were Eucalyptus odorata (peppermint box),
E
camaldulensis (river red gum), Acacia pycnantha
(golden wattle) and
Allocasuarina verticillata (drooping she-oak). It is likely that the
lack of a co-ordinated weed control programme contributed to the death of many of the
plantings and few of these trees can be seen today.
Since 1980, however, the Flagstaff Hill Scout Group has been involved in tree-planting
and weed eradication in the Craigburn addition. More recently,
seedlings have been raised from local seed sources and have had a reasonable survival rate
of 50—60%.
The following numbers have been planted over the years:
Many of these tree plantings, whilst better than introduced species and weeds
suffers from a lack of bio-diversity. Large numbers of a few species were planted randomly
but there has been little opportunity for regeneration of under story plants.
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