The issue was mainly in Northland where there was an ''unusual situation'' with a higher proportion of logs being exported than anywhere else in the country.
That was where overseas companies were buying up forests with the intention of export. He had not heard of any issues in Otago, he said.
Mr Cullen encouraged people to get good advice as to what their trees were worth to make sure any offer made for them was true value and to explore all options.
The NZFFA has 1700 members and represented small-scale forest growers - those with less than 1000ha of forest.
Small-scale growers owned more than 500,000ha of trees, representing a third of the national stocked area. Much of that was established during the 1990s planting boom and would be harvested in the next 10 years.