In a combined effort last week, National Parks and Wildlife Service(NPWS) officers, local bush regeneration contractors and volunteers from the Australian Trust for Nature Conservation tackled a major gorse infestation along Govetts Leap Brook in Blue Mountains National Park near Blackheath.

In an area of gorse described as "So thick you couldn't open your lunchbox in it." thousands of gorse plants covering an area of over five hectares were sawn down and poisoned during the week-long campaign.

The enthusiastic team of nine volunteers included visitors from Denmark, Germany, USA and Scotland and were expertly supervised by Hugh Paterson from the Good Bush People and Alan Oliver from A&S Bushcare Services.

Gorse, a noxious weed introduced earlier this century from Europe, was planted as a hardy impenetrable hedge on the windswept ridges of the Upper Blue Mountains.

Unfortunately gorse is a ferocious coloniser, capapble of spreading more than 20,000 seeds a square metre every year. Seeds are carried by water in creeks and streams and may lay dormant in the soil for up to 30 years. Gorse can grow to a size of a small tree and is covered by thousands of 3 centimetre long needle-sharp spikes.

Gorse is a major conservation problem because Blue Mountains National Park lies downstream of a number of infestations. Seeds have travelled down the creeks and colonised sandy areas on river banks along 50 km of the Grose River.

Govetts Leap Brook cascades into the Grose Valley at Bridal Vale Falls and forms part of the Hawkesbury-Nepean Catchment. Like many streams in the Blue Mountains, urban development in the upper catchment has provided the conditions favourable for weed growth. Nutrients, sediment, other pollutants and a weed seed source combine to inhibit the growth of native plants and encourage weed establishment.