Wood is a natural, renewable resource, except when it is harvested by clear cutting old growth forest or a rainforest. Here we will assume about 1/3 of wood from plantations and the rest from natural forest.
The following are reflected in the numbers below:
- Harvest of wood from a free-standing forest yields in average 100000 pounds of wood per acre.
- Planting, fertilizing, spraying with pesticides, and harvesting uses energy (mostly fuel for equipment) and chemicals, represented here by a quantity of oil.
- Forest is an important resource, but when cut, it is converted to land that can be put to other uses, thus we have a negative number for land used, corresponding to the amount of forest being cut.
- The area under timber plantations should be included. However, since the wood is produced continuously, an acre of plantation will yield, in time, any number of pounds of wood. Thus, the area used per pound approaches (in theory) zero.