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How to Measure Trees to Determine Their Board-Foot Volume and Value

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How to Measure Trees to Determine Their Board-Foot Volume and Value Illinois Forest Management Newsletter is produced by the University of Illinois Department of Natural Resources and Environmental Sciences and the Cooperative Extension Service. Our newsletter features information from many sources to help you make informed decisions concerning your woodland resources. We encourage your questions and comments which we will share with our readers as space permits. Direct your inquiries to: Editor, IFM Newsletter, W-503 Turner Hall, 1102 S. Goodwin Ave. Urbana, IL 61801. HOW TO MEASURE TREES TO DETERMINE THEIR BOARD-FOOT VOLUME AND VALUE We frequently receive calls from landowners who have been approach by a buyer who has expressed interest in their timber. The first question posed in the conversation normally is..."How do I know if I have been offered a fair price?"...and is followed by..."How do I know what my timber is worth?" Obviously there is no way of answering the first part of the question without walking the timber, making some observations, and taking some measurements. And even then, what is a fair offer to one person may be totally out of line to another. A buyer may be making a genuinely fair offer based on his ability to market the timber he buys. Another buyer might come along with a totally different set of markets and be able to make the first buyer look like an absolute crook in the eyes of the landowner. Who made the fair offer? Most likely both did, but their ability to market the timber reflects what they could afford to pay for it. The following example emphasizes this point. A recent sealed bid sale in Illinois brought bids in the range of $32,000 to $123,000. Most of the bids were grouped toward the bottom of this range. It's probably not hard to guess who the landowner sold to, and in fact, most of the unsuccessful timber buyers wanted to know how the successful bidder could afford to pay that much for the timber. As it turned out he had a veneer market for the large volume of sycamore logs that the others did not have. Our suggestion to landowners who know little about their timber or how to market it is not to get in a hurry and give serious thought to hiring a forester to represent their interest. Diameter Measurement Nationwide less that 10% of the timber sold involves a professional forester. In Illinois, this figure is probably closer to The diameter of the exposed end of a log is easily measured using 5%. The more you know about your timber, the better prepared a ruler or carpenter's tape. A standing tree presents a problem. you will be deal with unsolicited offers that come your way. You The standard point of measure for tree diameter is 4 1/2 feet may be pleasantly surprised to find that something you above the ground (above the ground on the uphill side if the tree considered to be of minimal value may, in fact, be worth quite a is on a slope). This is called diameter breast high, and is usually bit, and with a little management could be worth considerably abbreviated as "DBH." more in the future. Diameter tape To answer the second part of the question..."How do I know what my timber is worth?"...you could hire a consulting forester to A diameter tape can be used to measure a tree's diameter. The appraise your timber or you could learn how to measure and tape is calibrated to read the tree's diameter by measuring its evaluate the timber yourself. This article presents the basics on circumference or distance around its trunk. If used correctly, this tree measurement for landowners who want to learn more about is a very accurate measuring device and the tree's diameter can be the value of their timber. read to the nearest tenth of an inch. The two measurements used to estimate the volume of a tree or Diameter tapes cost about $20 to $50 each. If you wish, you may log are diameter and height or length. Determination of the use a regular cloth measuring tape to measure around the tree and volume of wood in a tree is surprisingly complicated. The main divide the reading by 3.14 to obtain the diameter. Measuring stem (bole), for one thing, does not fit any standard geometric DBH to the nearest even inch (12, 14, 16, etc.) is adequate for the form. However, volume tables have been developed that ease the forest measurements described in this article. A 12-inch tree has a cumbersome task of volume computation. DBH between 11.1 and 13.0 inches, a 14-inch tree between 13.1 and 15.0 inches, etc. Taking tree measurements requires the use of some simple instruments which can be purchased or made. If you decide to order the equipment described below, supply sources include: Ben Meadows Company 3589 Broad St. P.O. Box 80549 Atlanta, GA 30366-9821 1-800-241-6401 or Forestry Suppliers, Inc. 205 West Rankin St. P.O. Box 8397 Jackson, MS 39284-8397 1-800-647-5368 or International Reforestation Suppliers P.O. Box 4195 Pineville, LA 71361 1-800-321-1037 All have catalogs available which you can request. There are certain rules one should remember when using a The Tree/Log Scale Stick diameter tape. These are: A rather ingenious instrument, the tree/log scale stick, speeds the Be certain DBH is measured at 4 1/2 feet above the process of DBH measurements. It is not as accurate as the ground on the uphill side. If a tree forks below the measuring diameter tape, but if used with reasonable care it is adequate for point, measure it as two trees. If it forks above the measuring timber inventory work. Tree/log scale sticks cost around $10 and point, measure it as one tree (Figure 2). usually include the Merritt hypsometer used for estimating tree heights (described later). Do not let the tape sag-it must be horizontal around the tree (Figure 3). A purchased scale stick may not work for everyone since most are calibrated for use at a 25 inch distance (reach) from the eye. If your fully extend reach is less than 25 inches, the measurements you take with a purchased scale stick will be wrong. A scale stick can be easily constructed to fit any reach using the following formula: where: I = distance in inches from zero end of the stick to scale graduation, E = distance in inches from eye to the stick (your reach distance, which for many people is 25 inches), and D = tree's diameter in inches. A strip of wood about 1/4-inch thick, 1 inch wide, and 27 inches long can be used to fashion a scale stick. Use the formula above to mark off the DBH values on the stick. For example, if your reach is 23 inches, the diameter markings in Table 1 (next page) would be made on the stick as shown in Figure 4 below. Table 1. Distances to mark on a scale stick for DBH readings of your reach (the eye-to-stick distance you used to calibrated (Note: for a person with a 23 inch reach) your stick). Purchased scale sticks are normally calibrated for a 25 inch reach. Diameter Distance from Zero end of the stick in inches 2. Look directly at the center of the trunk. Without moving your 2 1.9 head, shift your eyes to the left side of the tree trunk and line the 4 3.7 zero end of the scale stick up with the left edge of the tree. 6 5.3 3. Without moving your head, shift your eyes to the right side of 8 6.9 the tree and observe where the tree's right side intercepts the 10 8.3 stick. This is the diameter measurement. 12 9.7 14 11.0 16 12.3 18 13.5 20 14.6 22 15.7 24 16.8 26 17.8 28 18.8 30 19.8 32 20.7 34 21.6 36 22.5 38 23.3 40 24.2 If you do not have a measuring tape marked in tenths of inches, the readings can be changed to 1 / 16" by the relation: measurement in 1/16" units = measurement in tenths 0.063 For the 12-inch DBH mark, the distance from the zero end of the stick is 9.7 inches, or 9 11/16 inches. Here's how to use the scale stick to determine the tree's diameter (refer to Figures 5 and 6). If you are using a purchased scale stick that has both tree and log scales on it, make sure you use the tree scale for both the diameter and height measurements: 1. Determine where 4 1/2 feet above ground hits you. Face the tree and center yourself on its trunk. Move up against the tree to determine where the 4 1/2 foot mark is on the tree's trunk. Hold the scale stick horizontally against the tree on the 4 1/2 foot mark and back away from the tree the length 4. Because trees are not round, it is good practice to take another This works because of similar triangles. That is, the length of the diameter measurement one-fourth of the way around the trunk (90 stick above your fist equals your reach so the tree's height equals degrees to your first measurement). Average the two the horizontal distance to the tree.
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