The planting marks the end of the first stage of an ambitious project to transform a bleak, windswept landscape bordered by the Murrumbidgee River and the Scabby Range.

"The new plantings include more than 2,500 native trees to regrow critically endangered Box Gum woodlands and will help with erosion control and restoration of the landscape," ACT Environment Minister Mick Gentleman said at a celebratory event at the site.

The ACT government has earmarked $1.73 million for the project.

The area was once a vast plantation pine forest until the bushfires in 2003, since when it has languished as rough scrub.

But not so much in the future as the plantlings mature into trees.

Thousands of radiata pine seedlings were germinated and planted as part of a two-year program which will cover 490 hectares with something like 500,000 trees.

The first phase has now been completed.

"Over 120 coir logs have also been installed to help with erosion and to capture sediment in drainage lines and shelter the newly planted vegetation, Mr Gentleman said

Senior forester Christian Bihlmaier said the project would take years before true completion.

"It will look a bit ugly for a while until the trees become established but once they gain hold, the pines grow about a metre per year," he said.

"We will retain the older gum trees where we can and down through the gullies and water courses, create erosion controls and plant out with native hardwoods.

"There are also areas of cultural value here which are being identified and protected."

Small patches of native woodlands are being retained but elsewhere the radiata plantations are being rolled out in a long-term program which the next generation of ACT foresters will see harvested around 2050.

Trees soak up carbon dioxide so a forest helps the ACT get its carbon footprint down.

The aim is to use the forest for recreation, including mountain biking and outward bound courses.