Woodlands and Wetlands Trust chair Dr Jason Cummings also told an inquiry on Canberra's green spaces that developers should be forced to make contributions to conservation projects through planning applications.

But the government has already ruled out adding new charges to June's budget.

Dr Cummings said about 30 other jurisdictions already charged about $100 through similar levies.

"It's not a contentious mechanism elsewhere in Australia," he said.

"For us it seemed like an obvious opportunity for policy change to generate more revenue for conservation so we could restore more places."

Dr Cummings said the levy had been proposed in a 2011 report by the then environment commissioner.

An ACT government spokeswoman said the government "does not intend that this will include new fees and charges" in the budget on June 4.

Trust president Alison Russell-French pointed to the cross-border Ginninderry development in Belconnen, where ACT home buyers would be charged a 1 per cent levy to go towards a conservation trust at Ginninderra Falls.

"A social due on communities as a whole is not a bad idea," she said.

"If you're going develop somewhere you pay a certain amount of social benefit back to the community to manage the areas."

Dr Cummings is also the Ginnindery Conservation Management Trust manager.

He said the $100 levy could be income-tested.

He said even developments or redevelopments inside existing urban areas should pay, citing Braddon's Haig Park as an example.

"People living around Haig Park, they are using the natural landscape ... they will be the people calling up Chief Minister talkback complaining the trails aren't being looked after," Dr Cummings said.

He said corporate leaders often formed partnerships with the trust, which looked after the Jerrabomberra Wetlands and the Mulligans Flat Woodlands Sanctuary.

"But there's a whole section of the economy that could do more if they were required through planning processes for example," Dr Cummings said.

"I think there could be, with minor policy adjustments, a lot more support coming from the business community."

Ms Russell-French said holistic oversight was needed for Canberra developments.

She also said ecological restoration should be a policy priority for the ACT government.

Meanwhile, CSIRO scientists told Wednesday's inquiry that research showed green space raised property prices, improved mental health and benefited the environment.

Their submission said Canberra's natural landscapes were important in mitigating climate change's impact on the capital.

Principal research consultant Guy Barnett said Canberra was ahead of the curve with some of its environmentally integrated design, but more could also be done to halt the reduction in tree canopy cover across the capital.

He also said water-sensitive urban design - projects like urban wetlands - were beneficial but needed more long-term monitoring to assess their impact.

Senior research scientist Dr Sorada Tapsuwan said better monitoring would help provide a cost-benefit analysis, encouraging more developers to use them.