Print Window Close Window Keep Your Units Straight Foresters measure timber in many different units, and it’s easy to get confused. Beware of those who switch units on you to make the numbers seem bigger or smaller! One common unit in the timber industry is the cubic foot—a three-dimensional volume of wood one foot on each side. In Canada (and most of the rest of the world, where the metric system is used) you’ll hear about cubic meters. Since a meter is a bit more than three feet, a cubic meter is more than 27 (three cubed) times bigger than a cubic foot. In fact, it’s about 30 cubic feet. Cubic measurements (whether feet or meters) are often used if the wood is being turned into pulp or small objects such as toothpicks rather than being used as lumber or dimensional timber. Dimensional timber is generally measured in board-feet in the US. A board-foot is a plank an inch thick, a foot wide, and a foot long. When trees are cut into planks, a considerable amount of the wood ends up as scrap (because trees aren’t polite enough to grow square), and some volume is turned into sawdust. Thus, for each cubic foot of tree, far less than twelve board-feet of lumber can be produced. Depending on the size of the tree, in the boreal forest one cubic foot is estimated to produce only three or four board feet. Many small trees might yield a fairly high number of cubic feet, but a relatively low number of board feet. Conversely, big old trees will produce more board feet per cubic foot. Sometimes foresters will simply talk about how many acres or hectares are being cut. An acre is equal to 43,560 square feet, or an area approximately 209 feet by 209 feet. A hectare is a metric unit equal to 10,000 square meters—approximately 2 ½ acres. How much wood comes from an acre of land can vary enormously, depending on the latitude, altitude, and soil quality, as well as the species, age, and health of the trees. Thus, converting between land area and timber units can be misleading. For example, you might be told that only 1% of the total acreage of a forest was being clear-cut; however, this 1% might contain 50% of the board-feet in the forest. Here in Interior Alaska, only a small portion of the forest has timber that is large enough to be considered desirable. While the slender black spruce of the muskeg and uplands are counted in assessments of overall forest acreage, it is the old groves of large white spruce, generally located near streams and rivers, that the timber industry wants. Not all acres are created equal. Thus, when reading any forestry document, make sure you understand your units! |