## Lesson 2 - How to measure a tree

How to measure a tree

The two measurements most commonly used to estimate the volume of wood in a tree or log are diameter and log length. Stem quality is also evaluated using a grading system that considers how large and straight a stem is and whether or not there are defects such as branches.

Measuring Tree Diameter

The convenient point of measurement is determined by a person's height. A standard point is 4 ½ feet above the ground (above the ground on the uphill side if the tree is on a slope). Stem diameter measured in this manner is referred to as "diameter at breast height" and is abbreviated "dbh". Diameter is usually measured with a special diameter tape sold by forestry supply companies. However, many carpenter's tapes have a scale on the reverse side for measuring units of diameter. Or, you may use a regular cloth tape to measure around the tree and divide the reading by 3.14 to obtain the diameter. Measuring dbh to the nearest inch is adequate.

Measuring Log Length
A tree may be thought of as a collection of logs and pulpwood. Small trees with dbh's ranging from 5 to 11 inches are only suitable for pulpwood. Trees greater than 11 inches dbh are suitable for sawlogs, from which lumber is cut. Typically, pulpwood is measured in 8 foot lengths and sawlogs are measured in 16 foot lengths. Because tree stems taper, the diameter decreases as you move up the stem. Once the upper stem diameter outside of the bark decreases to about 8 inches, the rest of the tree above that point is considered pulpwood. Measuring logs in a standing tree requires some practice. There are several instruments you can either buy or make for measuring the length of logs in a standing tree. For more details on this procedure call the Agriculture and Forestry Experiment Station at (304) 293-4421 or This email address is being protected from spambots. You need JavaScript enabled to view it. your request for "How to Estimate the Value of Timber in Your Woodlot" Circular #148 January 1989 By Harry V. Wiant.

Estimating Pulpwood and Log Volume
Pulpwood is often measured by weight at the point of delivery. A truck containing a load of pulpwood is weighed and the weight of wood is determined by subtracting the truck weight from the total weight. Sawlogs are the most valuable parts of the tree and accurate volume estimates are critical to receiving a fair price for you timber. Sawlog volumes are estimated in units of board feet. Simply, a board foot is the amount of wood in a piece measuring 12 inches square and 1 inch thick.

By using stem diameters and log lengths, three different "log rules" or mathematical equations, have been developed for estimating the number of board feet in a log. Request the publication mentioned above for more details. The three log rules are called "Doyle," "Scribner," and "International." The landowner selling timber is advised to estimate the volume of their trees using Scribner or International. Because the Doyle log rule underestimates board feet volumes, most timber buyers prefer to use the Doyle log rule. If you, as a seller, are not aware of this difference, you may settle for much less money than your timber is worth. Try to negotiate a volume estimate using either the International or Scribner rules, otherwise, make sure you negotiate a selling price that is about 40% higher per thousand board feet. Note: All of the tree value estimates in the web page are based on volumes determined using the International Log Rule.