The Wood Council is warning the wood-processing industry is under threat, with a predicted drop in tree numbers made worse by small lot owners selling their logs for export before they're fully mature.
It says more co-operation in the forest and timber industry is needed to protect it from fluctuations in high-grade log supply.
Wood Council chairman Brian Stanley said the annual wood cut was expected to drop by half, to 2 million cubic metres within five years, and wouldn't pick up for about 15 years - when the next trees would be ready to cut.
He said domestic processors already used about 2m cubic metres of wood and were reliant on small woodlot owners for future supply.
While it might be too late, Mr Stanley said he would like those selling their trees to get professional advice first.
"If they had taken those trees out to age 28 they would have done far better on their original investment.
"I guess if you want cash today and someone comes and offers you cash, then you are going to take that cash today, but if they don't the cash today and they just take it because someone is knocking on the door then they should think about taking them out to age 28 and get a better dollar return."
Mr Stanley said it was unlikely that small woodlot owners who sold their trees would replant more.
"If it is a piece of land that can easily go back into farmland then they will probably put it back into farmland."
He said that in itself posed a long-term problem and the industry needed to come together and think about it more inclusively.
"We need to stop competing independently of each other and bring some NZ Inc thinking into the forest industry if we really want to have a good future for the forest industry in New Zealand - working together, collaborating and insuring that we do have a viable industry."