IT'S a tree change - but not of the positive kind.

Safety fears, lack of family time and addiction to technology has created a generation of children who no longer climb trees.

New research shows only 20 per cent of today's children take part in the age-old pastime compared with 64 per cent of their parents.

The Climbing Trees: Getting Aussie Kids Back Outdoors study, released today, reveals 73 per cent of parents played outdoors more often than they did indoors when they were young, compared to only 13 per cent of today's children.

More than 70 per cent of parents said they played outside every day as kids, compared to only 35 per cent of their children. One in 10 of today's children play outside once a week or less.

Professor Anita Bundy, from Sydney University, said the results are concerning as outdoor play not only benefits children's physical well-being, but is also essential to social and cognitive development.

"When children play outdoors without parents shadowing their every move they learn social negotiation which is an important skill," she said.

"It helps them think creatively and problem solve. They also learn to manage risk and make sound judgments about what is safe and what is not."

Prof Bundy said the trend towards children spending more time indoors and less time playing outside has been increasing in recent decades.

"It is pretty intense in this generation, because these children are bubble and cotton wool wrapped like never before," she said.

The survey of more than 1000 people was commissioned by Planet Ark in the lead-up to National Tree Day which encourages children and families to spend time outdoors planting a tree.

Planet Ark's Rebecca Gilling said the main reasons parents gave for lack of children's time outdoors was safety and the fear of crime. "The world is not more crime-ridden than past generations but the perception is that it's more dangerous," she said.

Tilda, 8, and Eric Holmstrom, 10, were making the most of the outdoors in Centennial Park yesterday.

Their mother Anna said the family spent a lot of time outside.

"When they are outdoors they are forced to be more creative and come up with ideas for games themselves," she said.

"It is healthy for them to be out in the fresh air which means they are in a better mood and happier."