A tree and log scale stick is a must-have tool if you’re interested in harvesting lumber from woodlands on your farm. Small, lightweight, and relatively inexpensive, this tool will help you estimate the amount of usable lumber (in board feet) that any given tree might yield.
What is a tree and log scale stick?
A tree and log scale stick is long, narrow, and covered with numbers and marks to gauge the diameters and heights of trees. At first glance, it resembles a large ruler. They can be purchased from many places, or it’s straightforward to make your own so long as you get the ruler markings in the correct places.
The following instructions provide an overview that will apply to many models, but if your stick requires different distances for use, follow the instructions for your specific stick.
How to measure a tree’s diameter
On one section of the stick you’ll find narrowly spaced lines marked with numbers like 16, 18, 20, 22, etc. These are used to measure, in inches, a tree trunk’s diameter at breast height. Diameter at breast height is 4 1/2 feet above the ground, measured from the uphill side of the tree if it’s growing on a slope.
To measure the diameter, hold the stick horizontally against the tree trunk, exactly 25 inches from your face. Line up the left edge of the stick with the left side of the trunk. Now look at the right side of the trunk (don’t move or turn your head) and note which measuring line on your tree and log scale stick most closely lines up with the right edge of the trunk. If it says “26,” the diameter is 26 inches.
How to measure a tree’s height
On another section of the stick you’ll find widely spaced lines meant to measure how many log sections (typically 16-foot log sections) can be obtained from the trunk.
To count the log sections, walk 66 feet away from the tree, and hold your tree and log scale stick exactly vertical and exactly 25 inches from your face. Line up the bottom of the ruler with the bottom of the tree, but a little above the ground—wherever you would cut if felling the tree. Then use the measurement markings to count, from the ground up, how many log sections comprise the trunk before the trunk’s diameter grows to narrow to be useful or you encounter significant branching.
Calculating board feet from your measurements
Once you’ve taken diameter and height measurements, you can combine them to estimate how many board feet of lumber a given tree will offer.
Depending on your particular stick, simple guides may be printed right on the stick, telling you how many board feet of lumber a tree with X number of log sections and Y diameter at breast height will yield. But you can also research the Doyle, Scribner, and International 1/4-inch Log Rules to find easy-to-read data tables and even the underlying formulas for calculating board feet. The International 1/4-inch Log Rule is considered the most accurate, but the older Doyle and Scribner methods are still widely used in different parts of the United States.
Obviously, the estimates gleaned from a tree and log scale stick are just that—estimates. But an estimate is enough to give you an idea of how much lumber is in a stand of trees, and whether harvesting some of the lumber is a worthwhile project on your farm.
This article on how to use a tree and log scale stick was written for Hobby Farms online. Click here to subscribe.
