Private forest growers have used a parliamentary inquiry to raise concerns about Tasmania's forest peace deal.
Upper House MPs are holding a public inquiry into the peace deal legislation.
Australian Forest Growers chief executive Warwick Ragg says the bill is not in the best interests of all Tasmanians.
He says the durability arrangements are ineffective and will not stop damaging market campaigns.
"The provisions of durability, whilst highly commendable, do not seem to provide sufficient insurance against a meltdown of environmental support in the short or medium term," he said.
Conservationists claim the bill will not deliver peace in the state's forests.
Tasmanian Conservation Trust director Peter McGlone has told the hearing the bill is flawed and needs amendments.
"The TFA Bill and the Tasmanian Forests Agreement, if implemented unchanged, will not deliver a comprehensive forest conservation outcome, peace in the community or...also peace in the marketplace," he said.
Forestry Tasmania's chairman says the peace deal will challenge the state-owned company's commercial viability.
Bob Annells says the company supports the deal but would like to see minor changes, such as the issue of sovereign risk being addressed.
He says planning for new logging coupes is already underway.
"There is no doubt that reduced supply levels will challenge our commercial viability," he said.
"We will need funding support during that transition period especially for our non-commercial functions.
"However, we accept that government has made the decision to support the TFA in spite of this downside in order to achieve the goal of peace between deeply divided stakeholders." Study 'too late' The Local Government Association is concerned about the impact of the deal on local communities, saying the Commonwealth's socio-economic study has come too late.
Chief executive Allan Garcia says the Commonwealth's funding of the study should have come two years ago.
He says councils feel ignored in the peace deal process when they will have to deal with any fallout, including job losses.
"They are angry at having to deal with these issues and then not getting any cut through, you know there's no cut through from the state." "I don't think there's been much recognition of the fact that the issues that are existing now aren't just going to happen when the IGA finally gets implemented.
"These issues are existing now." Tasmanian flooring producer Oakdale Industries has told the inquiry it may be forced to import timber from Victoria if the forest peace deal is implemented.
Oakdale requires the equivalent of 6,000 cubic metres of sawlogs a year.
Phil Bayley from the Chamber of Commerce and Industry says it is likely Oakdale's supplies will dry up if the bill is passed.
"The idea of a Tasmanian disability enterprise importing wood from Victoria is preposterous, given both the supply that should be available and the cost differential that bringing in wood from Victoria would entail," he said.
Federal Environment Minister Tony Burke has returned to Hobart.
It is understood he is here for further meetings with Legislative Councillors.