The action affected five Carter Holt sites in South Australia and involved about 700 employees. They say log prices charged by Forestry SA are unsustainably high in the current economic climate and in the face of cheaper imported goods.
Forestry SA said it had negotiated with Carter Holt, but the company had demanded prices that made growing trees unsustainable.
Union organiser Brad Coates said the intention was not to hurt the industry or Carter Holt, but to send a clear message ot the government, which was refusing to interfere.