"It's a quick cash crop and a lot of forests are on private land, on farmers' land," said Mr Hansen.
"What we wood processors are saying is it's a log grab and we need to somehow manage and harvest a critical resource so that it's sustainable in the long term," he said.
From the 4.8 million cu m of mostly pine trees harvested in Northland every year, he said wood processors used only 2 million cu m and the rest was exported.
Ideally, between 2.7 million cu m and 3 million cu m should be harvested annually, he said.
In the year to June 2016, Mr Hansen said 2.7 million cu m of logs were exported out of Northport in Marsden.
He said China was the biggest importer, followed by India and Korea.
Mr Hansen said, although harvesting was currently at its peak, a shortage of logs would start to be felt in the next six to 10 years and there would be a "massive fall" from 2025 right through to 2042.
From the 2500 people employed by the forestry sector in Northland, he said 1600 worked at wood processing plants and a loss of employment for the whole lot would be a massive blow for the region.
"If these buyers are only buying the cutting rights and are buying under $100 million, there is no OIO (overseas investment office) requirement.
"If they are buying the land too, which is happening, then all they have to do is to prove they are good corporate operators and they will benefit NZ by exporting more logs.
Processors are barely considered," Mr Hansen said.
The Wood Processors and Manufacturers Association chairman Brian Stanley said the pillaging of our forests could not continue and that the sector should be treated the same as other national strategic asset such as land, minerals and fisheries.
Road Transport Forum chief executive said forestry owners have the right to harvest logs when they saw fit and importers to buy logs whenever they wanted.
The forum represents road transport companies, including logging truck operators.
New Zealand First Leader Northland MP Winston Peters said the plundered forestry sector was heading for a major crash unless steps were taken to restrain the excessive exporting of raw logs.
"The growth of unprocessed log exports, mainly to China, has got out of control and it is destroying any chance of growth to the value added sector here in New Zealand," says Mr Peters.
"Today we have no control, no laws, and no careful and astute management of one of our greatest resources."