Forest and Bird is closing seven reserves to try to stop the spread of kauri dieback disease.
Kauri tree showing lesions that indicate the start of dieback disease. Photo: RNZ / Cole Eastham-Farrelly
The group said there had been a lack of leadership in the fight against the disease by the Ministry for Primary Industries and it was left with no choice.
Chief executive Kevin Hague said each year hundreds of people enjoyed the reserves covering nearly 250ha in the North Island.
Though all are believed to be disease free, they will close immediately.
"The public entering those reserves could unwittingly introduce kauri dieback disease and that's a disease that's threatening the survival of probably our most iconic tree," Mr Hague said.
"We don't think we can ethically afford to wait any longer before we do this."
Signs will be up soon informing the public of the closures. Mr Hague hoped people would respect the closures.
Forest and Bird would consider enforcement if closures were not respected, he said.
Mr Hague believed the more tracks were closed, the more the message about kauri dieback would reach the general public.
"We want people to be able to experience the natural world so they will be become better advocates for it.
"But right now ... the bigger priority has got to be protecting them because we are seriously at risk of losing this tree within our lifetimes."
Mr Hague believed the public wanted to do the right thing but mixed signals from the ministry about closing tracks while keeping others open had led to confusion.
Environmental consultancy The Catalyst Group practice leader Marie Brown said Forest and Bird had made a sensible decision.
Individuals had been forced to take matters into their own hands because the ministry had been slow to act, she said.
"As a result we have the disease marching through reserves."
Auckland Council's former biosecurity manager Jack Craw also supported the closure.
Kauri dieback was a crisis and the ministry was taking too long, he said.
"They need to put a crisis management plan together and they need to start tomorrow.
"That plan should include surveillance of all kauri reserves and [that should be] completed in three to six months - it might need 100 people, so be it."
All livestock needed to be removed from infested areas and put cleaning stations, he said.
Ministry for Primary Industries head of biosecurity Roger Smith said he supported Forest and Bird's move to close the reserves.
Closing forests was the responsibility of the landowner, and the ministry offered help relating to any council-owned or conservation land, and was working closely with Auckland Council on shutting down public areas in the Waitākeres.
"This is a shared effort and we're working with a wide range of stakeholders" - MPI head of biosecurity Roger Smith
Decision-making also involved the Department of Conservation, tangata whenua and councils, he said.
Reserves to be closed:
- Morgan Reserve (Waikato)
- Ngaheretuku Reserve (South Auckland)
- Matuku Reserve (Waitākere)
- Kerr-Taylor Reserve (Waitākere)
- Onetangi Reserve (Hauraki Islands)
- Te Haahi-Goodwin Reserve (Hauraki Islands)
- HB Matthews Reserve (Far North)