Ecologists, Yarralumla residents, university students and Ngunnawal people are uncovering a grassy woodland full of threatened button wrinklewort, sticky everlasting and hoary sunray flowers, and Aboriginals' rich cultural past.

A stream once flowed from Capital Hill to the Molonglo River, which became a birthing place for women, a place for secret women's business, says Ngunnawal elder Wally Bell.

Yarralumla resident Peter McGhie, and Friends of Grasslands president Sarah Sharp, say the National Capital Authority, which four years ago wanted to develop some of the land for diplomatic missions, had now become a supporter, buying weeding tools for volunteers.

New embassies are unlikely to be built in Stirling Park after a parliamentary inquiry backed objections of residents to the controversial proposal, and criticised the ad hoc approach to allocating land for new missions.

Mr McGhie's monthly newsletter updates about 90 like-minded people on Stirling Park clearing of cotoneaster, hawthorn and blackberry, and the planting of 150 trees and shrubs native to the area. Mr McGhie says the location is outstanding.

"There is a small pine plantation down at the lake end of the park and if those were cut down you would have glorious views from a sloping hillside over the lake. It would be the best land in Canberra," he said.

Mr McGhie draws a parallel with major overseas cities, like New York's Central Park, for example. "Here [in Canberra] is the city virtually within walking distance, [and] 52 hectares of bush with walking tracks and wild flowers; that is quite unique."

Unlike Central Park, Stirling Park has more ant beds and foraging birds than people, and smells of eucalypts and warm grass. Some of the fat gum trees are 350 years old. Ms Sharp says the profusion of button wrinklewort is matched by birdlife. "It is an important area ecologically because it is a sort of east to west connection between Molonglo and on to Red Hill, a key area for bird movements and other animals."

Ms Sharp said under the NCA's previous, sporadic management the site was "falling through the cracks," but this reversed under the NCA's current asset manager, Peter Beutel.

The top of the ridge was once considered the most appropriate site for the Prime Minister's Lodge, but that idea has since been abandoned. Ms Sharp says it's time Aboriginals were able to become involved in the land management.

Mr Bell said well before Parliament House, Capital Hill was a major meeting place for several tribal groups and Acton peninsula was a pathway. Now numerous stone artefacts, including hammer stones and ground axes, could be found around Stirling Park.

The area had cultural sites for men's business and women's business. He had been surveying a section with Molonglo Catchment groups' Karen Williams when he inadvertently stepped into the women's area. "As an Aboriginal man I wandered on to this area, I felt quite ill. Once I stepped out of the area I was fine again," he said.

"One of the best tools we use as Aboriginal people of course is fire. Under ACT fire management we are not allowed to do that."

His people have been talking with government authorities about doing cool burns. which take off the top layer of a burn area, unlike ACT-initiated burns which create hot burns, destroying what is on top of the ground and what is below.

Red Hill Regenerators volunteer Paul Ratcliffe says government agencies can do the big picture weed control, but volunteers are needed for more time-consuming hand weeding.