She also tells the story of how the Forest Service was set up to preserve the native forest and stop it from being completely cut out.
Mrs Orr said they were not altogether successful with this and conservationists came along in the 1970s.
However, in the long run the Forest Service worked out good ways of having sustainable forestry in the bush, she said.
She said, at the end of the book, she makes a plea to politicians for better preservation of our biodiversity.
Mrs Orr started research for the book in December 2008. She said the book was a co-operative effort, having received help from more than 40 former members of the Forest Service.
Quite a lot of these members were Rotorua people, particularly associated with Scion, she said.
"I am rather delighted at having actually finished writing it."
Mrs Orr said almost all the people who attended had helped to keep New Zealand green by what they had done.
As well as being the author of Keeping New Zealand Green, Mrs Orr is best known for her part in the passing of the 1972 Equal Pay Act, and as the first woman chancellor of Victoria University of Wellington.
The book is available at book stores and at steeleroberts.co.nz.