Green spaces can have psychological effects, Dr Cameron says
The loss of green space has a serious impact on quality of life which should be recognised by planners and politicians, a scientist has argued.
Dr Ross Cameron said 32 sq km (12.3 sq miles) of London gardens had been lost to housing development in five years.
The environmental and health benefits of gardens were being underestimated, the horticultural expert said.
Meanwhile, botanist David Bellamy has unveiled a plan to reintroduce native Elm trees to the British countryside.
Speaking at the British Science Festival, Dr Cameron a from Reading University, said green spaces helped prevent the "heat island" effect that made urban areas warmer than the countryside.
They also encouraged physical activity and had a wealth of beneficial psychological and social effects, he said.
A green environment was known to reduce stress and anxiety, and research in the US also showed it lowered the crime rate.
Dr Cameron said when comparing two similar social housing schemes in Chicago, scientists found that the one with more greenery had a third less crime.
"The greatest reduction was related to domestic violence, which is associated with anxiety," he said.
Urban gardens are technically defined as "brownfield sites" and not protected by planning laws, Dr Cameron told the meeting. He said there was an argument for giving them "greenfield" status.
"There needs to be a dialogue about the importance of green space and its loss," said Dr Cameron.
"Up to now, the attitude has been 'there's some spare ground, let's build on it'. But that has implications for quality of life. Green space is not a luxury."
It comes as the Conservation Foundation, set up by Professor Bellamy, is hoping to reintroduce native elm trees to the British countryside.
It has grown saplings from trees believed to be resistant to Dutch Elm disease that are more than 60 years old.
In the 1970s more than 20m elm trees succumbed to the fungal disease in the UK, a loss that dramatically changed the face of the countryside.
The foundation admits their project is an experiment and it will be decades before they know if the saplings are resistant to the disease.