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Friends of Sturt Gorge

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MU17 opposite 21 Bushland Drive

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Restoration of the grey box grassy woodland plant association

By Amy Blaylock

Restoration work at the eastern end of Bushland Drive , Bellevue Heights, began in 1999 with the adoption by one of our members of a ‘Bushcare’ site adjacent to the road. This site is approximately 50m wide, stretches down to Magpie Creek and is bordered on the eastern side by a walking track. Working bees over 5 years have progressively removed a thick understorey of boneseed and olives on this site, which has allowed the native plants to flourish and spread. Regeneration of native apricot (Pittosporum phylliraeoides) and green hood orchids (Pterostylis sp.) have been the most noticeable improvements to date. The site has excellent displays of orchids and native lilies during spring, and a good understorey of grey box woodland plants such as Sweet Bursaria (Bursaria spinosa), Golden Wattle (Acacia pycnantha), Kangaroo Thorn (Acacia paradoxa) and drooping sheoak (Allocasuarina verticillata).

June 1999 Click on image to enlarge

December 1999 Click on image to enlarge

In 2002, the Friends of Sturt Gorge Recreation Park received a grant from the City of Mitcham through its Community Development Scheme, to continue this restoration work at an adjacent site to the east of the walking track. This new site is bounded by a drainage line from a side entry pit and a tributary of Magpie Creek. It was chosen because (a) it represented a significant potential weed source for the restored site, (b) weed control on the site would allow the native vegetation still present to regenerate or germinate from the seed bank and (c) its restoration would increase the visual amenity of the area and reduce the bushfire load.

Our working bees during 2003 have concentrated on the removal and in situ poisoning of the woody weeds boneseed (Chrysanthemoides monilifera) and olive (Olea europaea) which formed a dense understorey on the site. This project has been very successful, with the work site now cleared of all boneseed and small olives, and most large olives frilled and poisoned. This project is ongoing and several working bees a year will be spent maintaining this area.

Above is a picture of Bushland Drive site showing the frontier between Boneseed weed infestation and area cleared.
This site has a number of species of orchids that can be seen flowering in October.
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Bushfires at Bushland Drive (March 2005 Newsletter)

by Pat Bowie

On 28 November 2004 the CFS extinguished two fires, a few hundred metres apart, one of which was just inside the Bushland Drive section of the park, on its eastern boundary.

This gave the Friends group an opportunity to do follow-up work after a fire, and the working bee on 15 January was spent in this area.

Friends group inspecting burnt area (click to enlarge)

There had been some rain following the fire, and regrowth was evident, both in native and introduced species.

Regrowth of black berry (click to enlarge)

While it was satisfying to see regrowth at the base of a number of Eucalypt microcarpa trees it was less satisfying to see similar regrowth occuring at the base of an olive and several Dog Rose shrubs!

Regrowth of Eucalyptus microcarpa and Rosa canina (click each to enlarge)

The destruction by fire of an Acacia Paradoxa enabled us to remove formally inaccessible Boneseed plants. Seedling acacias and boneseed had already germinated.

Acacia seedling emerging (click to enlarge)

Non-native species that were cut and swabbed were Desert Ash, Blackberry (regrowth), mature Dog Rose shrubs and Broom.

Mature Dog Rose (click to enlarge)

It was also an opportunity to give two Mt Lofty Grass-trees (Xanthorrhoea quadrangulata) “room to breathe” by removing Desert Ash from around one and an Olive tree, whose foliage almost completely obscured the other.

Before and after of Grass-tree work(click each to enlarge)
Unfortunately, the chainsaw developed a problem before all the work in this area could be completed, so the next working bee will see us return there

Removing mature Ash trees with chainsaw (click to enlarge)

Why ash trees?

by Amy Blaylock

Desert ash (Fraxinus rotundifolia) is a deciduous tree that is native to the Mediterranean and SW Asia . It can grow to 20m or more and spreads into open vegetation, such as the grassy woodlands or creek lines of the Mount Lofty Ranges . Its winged seeds are spread by wind and water and its roots can sucker. Popular as a street or garden tree because of its hardy nature and summer shade, desert ash lines the Sturt River and several of the creeks and drainage lines that feed into the Gorge.

Unfortunately these characteristics and the many understorey saplings that these trees produce make it difficult for native riverside plants such as sedges, rushes and shrubs to become established.

Exotic species of trees such as the Desert Ash also affect the quality of fresh water entering the sea from rivers and streams. Deciduous exotics drop a large quantity of leaves all at once in Autumn which contributes to problems such as less oxygen and light and more nutrients in the water which, as it reaches Gulf St Vincent and the seagrass beds, causes algal growth which, in turn, inhibits the regeneration of this Leafy Seadragon habitat.

Indigenous species, on the other hand, drop a continuous but small amount of leaf material through out the year, causing less of a problem.

Through a Mitcham Council grant, we contracted Better Bushland to remove some large ash trees at the top of a drainage line off Bushland Drive at Bellevue Heights . They were chain-sawed at ground level and poisoned, and Department of Environment and Heritage staff were kind enough to mulch and remove the wood. We have been following up the dense understorey of young trees, and gradually working our way down the hill.

Cut and poisoned ash stump

We are making every effort to minimise soil disturbance and will put hay bales into the channel before winter, so that stormwater run off from Bushland Drive does not further erode the surrounding soil. The removal of this dense patch of ash trees will allow light back in at ground level, which may favour new weed species, but by working gradually on the area, with minimal soil disturbance, we can reduce the chances of new weeds and erosion.

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