Heating with Wood
How much forest land does it take to keep a northerner's house perpetually in firewood?
To answer this question we begin by defining the size and heating requirement for an "average" interior Alaska house. Axel Carlson of the University of Alaska's Cooperative Extension Service defined an average house as one having about 1200 square feet of floor area and needing 176 million BTU's for heat each year. It would take about 1250 gallons of fuel oil each year to heat such a house.
By photosynthesis, the plants growing on an acre of land can convert and store about 200 million BTU's of solar energy each year. So, in principle, it would seem that an acre could supply a house. In practice, though we burn only tree trunks and perhaps the largest branches for house heating. This plant material is produced at a far lower rate.
Forests considered to be just marginal for commercial wood production in Alaska and Yukon will yield about a fifth of a cord of trunk wood per acre each year. Since it takes about 12 cords of wood to supply the 176 million BTU's for our average house's annual heating, as much as 60 acres of marginally commercial forest land are needed to supply the house year after year on a sustained basis.
Of course, the more productive forest lands bordering the Gulf of Alaska will produce trunk wood at a far higher rate. Balsam poplar and black cottonwood stands of southern Alaska are reported to produce well over a cord of wood per acre annually. So perhaps a 10-acre stand of these hardwoods could supply the heating requirements of a house indefinitely.
