Have you ever measured a 2” X 4” piece of lumber and wondered why its actual dimensions are closer to 1.75” X 3.5”?Have you ever heard people in the timber industry mention the “dbh” of a tree. and wondered what the heck they were talking about?
These are two of a number of timber industry questions you can have answered this weekend at the Missouri Department of Conservation’s building at the Ozark Empire Fair.
Specifically, these questions and other forestry-related queries can be answered at the sawmill MDC staff will operate this weekend (Thursday-Sunday) and next weekend (Aug. 1-2) at its building on the west side of the fairgrounds. The purpose of this exhibit is to explain the huge economic and conservation impacts that wise forestry management has on this state. More on that in a bit, but first, here are answers to those questions:
Yes, it’s true – the 2” X 4” you buy at lumber yard or hardware store measures less than that. What it’s called – a 2” X 4” – is the piece of lumber’s “nominal dimensions;” what it measures are its “actual dimensions.” Lumber’s nominal dimensions are given to green, unfinished pieces. The finished size is smaller as a result of drying (which shrinks the wood), planing (which smooths it), and kerf (the amount of wood lost during sawing). The amount of “shrinkage” varies for different types of wood and kerf removed by a band saw will be different than lumber cut with a circular saw.
If you’ve discussed selling timber on your land with a logger, you may have heard the term “dbh,” which stands for “diameter at breast height.” In the U.S., a dbs measurement is the diameter of a tree at 4.5 feet above ground. (Some other countries have slightly different heights for dbs measurements.) One of several things a tree’s dbh helps a forestry professional determine is how much commercial wood is retrievable from a tree. A dbh measurement can also be used to estimate a tree’s carbon storage and, in some cases, its age.
From an economic standpoint, Missouri’s forest product industry contributes $8 billion to the state’s economy annually and supports 42,000 jobs. It’s estimated trees along streets in Missouri’s communities provide $148 million annually in benefits such as energy savings, property value increases and stormwater retention. It’s another example of how conservation pays by enriching our economy and quality of life.
And, of course, trees work for Missouri’s environment as well as its economy. One hundred mature trees can intercept 100,000 gallons of rainfall, which reduces run-off and provides cleaner water. For each pound of new wood that grows on a tree, approximately 1.3 pounds of oxygen is produced.
Through wise timber management, landowners can realize both the economic and environmental value of trees. Since approximately 85 percent of the state’s forest land is in  private ownership, the state’s landowners will play a huge role in what kind of forests future Missourians will be able to enjoy. Such management practices as even-age timber harvesting, smart-growth building practices in timbered areas and well-placed plantings of native species are some of the things landowners can do to maintain and enhance their timber.