A series of submitters told Parliament's Environment Select Committee the law was badly designed and would be expensive and ineffectual.
One submitter, chief executive Tony Clifford of Hawke's Bay wood company Pan Pac, said the law would give too much power over the industry to a small group of people.
"One of our key concerns is the power [in the bill] to make rules and impose costs onto the industry when very little cost-benefit analysis has been undertaken," he said.
"In our case, we just see [the law] as being cumbersome and unworkable."
Other criticism came from Don Wallace of the Farm Forestry Association, representing about 100,000 people owning shares in 14,000 small forests - many of them making little money.
He questioned the need for a new forestry authority when its work was already being done by several state and private organisations.
"We make a small amount of money out of our forests but we will lose much of that if we have to pay for another agency to duplicate the work of others that already exist."
John Tanner of the Wood Processors and Manufacturers Association came out in support of the changes, saying his industry was suffering from a shortage of logs and needed help.
"Wood processing companies are going under as we struggle to acquire a supply of logs," Dr Tanner said.
"We have recently lost a thousand jobs in six months, and that was before Covid-19."
Tanner said governments overseas were encouraging aggressive buying of New Zealand logs, at prices New Zealand mills could not afford, by subsidising their own industries, in contravention of WTO trading rules.
'This is cost-add, not value-add'
Rotorua forestry consultant Don Hammond told the select committee the proposed legislation was so bad, it did not appear to know what the problem was, let alone how to fix it, and would only make everything more expensive.
"Is Parliament saying this bill is more urgent than that one was?
"Is Parliament saying this bill is more important to be passed, so we can quickly place more clipboards and red tape in the forestry sector than to remove AR15s from the community?