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28 Oct 2008
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Not many high dunes have survived in the Sydney suburbs.

Avalon Dunes, 35 km north of the city, has a full range of coastal dune vegetation, ranging from spinifex grass and hardy front line shrubs on the foredune to littoral rainforest in the protected northwest corner.

In the 60s sand dunes were seen as a useful source of building sand. When in protest at the loss of the dunes, some local people blockaded the bulldozer , the removal stopped, but not until a large area of the northern dunes was removed from the present Barrenjoey High school area.

Dune vegetation provided forage for elephants for the nearby Ashtons Circus in the 60s The dunes were for fun. Many people recall coming to Avalon to slide down the dunes, which rise to about 22 metres above sea level.

With loss of native vegetation, the sand became unstable and when sand blew into Avalon village in the late 60s, the NSW Soil Conservation Service reshaped, planted and fenced the dunes into several “paddocks” to regulate beach access. Was this when bitou was planted? By the late 80s bitou covered about 80 percent of the dunes, with native vegetation having a battle to survive.

In 1989 Warringah Council began clearing in the paddock near the south next to the surf club. Next year our volunteer group formed to pull up the thousands of seedlings that popped up and to extend work into other paddocks.

Our technique then was to cut and paint stumps with glyphosate, removing the bitou to the tip.

By chance we learnt that bitou is sensitive to glyphosate at concentrations of 1:200 or 1:300 during the winter months. Most native plants such as Acacia sophorae are not affected. This technique really speeded up the rate of work when grants from Coastcare and the Sydney Northern Beaches CMA enabled us to engage bush regeneration contractors.

Dead bitou was crushed to form mulch into which thousands of tubestock was planted. Brown areas show dead bitou among living native shrubs.

Bare areas called blowouts mean sand is on the move, but as work continued these were covered by regenerating native vegetation.

Before and after photos tell the story of the swing from weeds to native vegetation. Pittwater Council supports the work with regular contract bush regeneration.

Now bitou is is a minor weed but others weeds need ongoing work. The garden plant Gazania is a problem . It can survive front- line wind and salt anad its seeds blow under Acacia and when that dies after its usual lifespan, it can form a monoculture.

Our volunteers are still meeting on the dunes once a month. Some have been turning up for 18 years. We won the NSW State Coastcare Award in 2007 for the dunes project , but the work goes on.

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