"We have to fight to make sure the ranges stay as we know them. By that I mean, I know they were decimated by forestry and subdivision but what we want is people who come back after 30-40 years saying, 'it's not too bad ... exactly the way we remember it'.
"We are trying to achieve this sense that there's one place that stays the same - against all the odds of subdivision and development and council plans and government plans.
"I think it is not too bad and is how I remember it, which is wild - wilderness - and there have to be places like that for people to enjoy."
Through the society's efforts, 1000ha has been donated to boost the reserve network, which includes 8500ha of Centennial Memorial Park and gifts of land going back to the 1920s.
Mr Edgar is an internationally recognised sculptor who lives at Karekare. When he was growing up in Mt Albert, his parents took him on visits to the ranges. Now he takes his 8-year-old grandson Myer Cuthbert there to share his enjoyment and knowledge.
Myer is named after his great-grandfather, former Auckland Mayor Sir Dove-Myer Robinson.
"I like [that] there are lots of trees, nice beaches and long walks and it's away from the crowds," he said.
"I climb trees and swim in the creeks if it's warm."
Regrowth of bush and the hard work of planting volunteers have restored scrubby areas. Mr Edgar said the ranges have got better as people understand the need for a good environment.
But the society needed more young people to fight to save the ranges, or the society would just grow old.
The heritage area act requires any council decision affecting the heritage area to be considered against the act's objectives, though its aims of protection are promoted through the Resource Management Act and Local Government Act.
However, Mr Edgar said this meant the society must resist Government moves which would weaken the Resource Management Act.
The society was also concerned about the ranges' place in the Unitary Plan rules for growth and needed to get the heritage area left out of the scramble to quickly build houses in the Auckland region.