Primary wood exports are New Zealand's fastest growing export earner.
A report from the New Zealand Institute of Economic Research shows primary wood exports grew an average 18.6% each year since 2006. Processed wood exports have grown only 3.5% in that time.
The report shows forestry and wood processing exports combined to earn $4.6 billion in the year to March, placing it third behind dairy and metal products in export income.
But First Union says the unprocessed wood industry is hurting wood processers, including saw mills and paper manufacturers.
General secretary Robert Reid says about 20 wood processing companies have folded in the past few years as they could not afford escalating wood prices.
He says that has led to the loss of 2000 wood processing jobs.