People ask me this question from time to time (I know, I know, I should get out more). The table below is from an article by Chris Barr and Christian Cossalter of the Centre for International Forestry Research in Indonesia (click on the table for a larger image):
Here’s how the calculation works. To produce one million tonnes of pulp, 4,150,000 m3/yr of wood is needed. Carr and Cossalter assume that 20% of the harvested volume is non-commercial. You need to know the growth rate of the plantations to supply the mill. Let’s assume 28 m3/ha/yr.
20% x 28 = 5.6, therefore the commercial volume = 28 – 5.6 = 22.4 m3/ha/yr.
4,150,000 / 22.4 = 185,000 hectares.
So, supplying a one million tonne a year pulp mill from plantations with a growth rate of 28 m3/ha/yr would require a net plantation area of 185,000 hectares.
Barr, C. and C. Cossalter (2004) “China’s development of a plantation-based wood pulp industry: government policies, financial incentives, and investment trends“, International Forestry Review, Vol. 6 (3-4).