Forest and Bird says more than 100 Department of Conservation staff are about to lose their jobs, reducing the ability of front line staff to manage conservation land.
DoC has confirmed a new structure will be discussed with its 1800 staff on Tuesday. It will be the latest in a number of changes since 2010.
Forest and Bird advocacy manager Kevin Hackwell says all the signs are that more jobs will be lost in this restructuring lost than last year when 96 staff were axed.
He says DoC's budget for the past year was $335 million - $25 million less than in 2008.
Mr Hackwell says the department plans to rely more on volunteers and enter commercial partnerships.
"We've got a fairly good idea about what's going to be said on Tuesday," he says. "It's going to be people losing their jobs, it's going to be spun to the public as 'Well, it's all right we're using volunteers and we're doing more and more work with business etc', and it's just not going to be good enough."
DOC says it will tell the public what the restructuring means after its 1800 full-time staff find out on Tuesday.
Cuts predicted in area offices
Auckland University ecologist Jacqueline Beggs says whereas previous cuts have been in the department's regional and national offices, this round will focus on the area offices.
She says the department's frontline rangers are based in those offices, which cover large areas of the provinces.
Ms Beggs says DoC is already feeling the strain of properly managing conservation land and is seeking volunteers and partnerships with corporations to fund projects.
Forest and Bird's West Coast field officer, Jen Miller, says already the department can no longer properly maintain conservation land and important projects are being missed.