Simple homemade forestry tools for resource inventories

 Try out these low-cost ideas from a new WSU Extension publication and make enough tools for the whole family to help …

Purchased versus homemade tools

Homemade tools are useful to landowners just getting started with their forest inventory. These tools are inexpensive and accurate enough for most surveys. The tools described in this article were made from scrap materials and their construction required only simple hand tools and average carpentry skills. For landowners interested in commercial quality tools, a list of them can be found on the WSU Extension Forestry website.

The purpose of a forest inventory

An inventory is one of the cornerstones of forest stewardship planning and is an important part of creating and maintaining a healthy and productive forest, as well as meeting your objectives as a landowner in the long term. To assess the needs of your forest and plan for the future, it is important to know what resources you currently have. An inventory will quantify your resources and identify your needs and your opportunities concerning forest health, wildlife habitat, timber production, aesthetics, and carbon storage. An inventory also provides information on species composition, tree density, basal area, and volume, and it will help you track growth and change in your forest over time.

A forest inventory is conducted by measuring a representative sample of the forest ecosystem and then applying that sample to a full forest. This process is called a cruise. Often there are too many trees (or other resources) to measure within a reasonable amount of time and effort. Cruising allows you to measure the forest in an efficient manner.

What you measure or sample in any cruise must meet your specific objectives. If you need to know tree density, stocking levels, and species, it makes sense to sample that information, and these tools can help with that process.

A Sampling of Homemade Tools (see the WSU Extension publication “Simple Homemade Forestry Tools for Resource Inventories” for a complete list of materials and instructions, and more homemade tool ideas.)

Diameter tape compared to carpenter's rule.
Diameter tape compared to carpenter’s rule. Photo: Publication EM038E/WSU Extension

Diameter tape (D-tape). A diameter tape, commonly called a D-tape, is used to determine the diameter of a tree. In the United States, all forestry volume tables use tree diameter as a variable, but with this tape, you actually measure the circumference of the tree trunk. The D-tape (using a cloth tape and a permanent felt-tip pen) records your mea­surements in diameter units.

Tree caliper
Tree diameter caliper. Image: Publication EM038E/WSU Extension

Diameter caliper. A homemade tree caliper measures tree diameter by sliding the sections together until the “jaws” are up against each side of the tree. The sliding sections of the caliper must be tight against each other to keep the jaws parallel.



Tree height angle gauge.
Tree height angle gauge. Photo: Publication EM038E/WSU Extension

Tree height angle gauge. A tree height angle gauge is a useful tool for measuring the angle from the ground to the top of a tree, snag, cliff, and/or other object. Once this angle (in degrees) and the horizontal distance to the tree have been determined, the height of the tree or object being measured can be calculated.

Cruiser or 'Biltmore' stick positioned to measure tree height
Cruiser or ‘Biltmore’ stick positioned to measure tree height. Photo: Publication EM038E/WSU Extension

Cruiser or “Biltmore” stick. A cruiser stick is a piece of wood similar to a yardstick used for estimating tree diameters and tree heights. More advanced sticks will also allow you to estimate tree or log volumes. 

Plot square assembly.
Plot square assembly. Photo: Publication EM038E/WSU Extension

Plot squares. Plot squares are commonly used for very small subplots during a cruise to measure what is present on the forest floor. Plot squares made from metal or wood are best because they retain their shape and thus their known area. Shrubs, herbaceous plants and grasses, wildlife droppings, mushrooms, and even human artifacts can be sampled using this tool

basal area guages
Basal area gauges. Photo: WSU

Angle gauge for basal area. Basal area is the cross-sectional area of a tree at 4.5 feet above ground. The basal area of all trees in a given land area indicates the degree to which a larger area is occupied by trees and is generally expressed in square feet per acre (ft2/acre). Using an angle gauge for 5, 10, 20, or even a 40 basal area factor (BAF) is common in the Pacific Northwest. A homemade angle gauge can easily replace a more expensive commercial prism.

Calibrating your thumb to measure basal area.

Your thumb can actually be used for an angle gauge in variable plot cruising too.


Although homemade forestry tools are not as accurate or as easy to use as commercial ones, they may be quite useful to the forest landowner who is not ready to invest in expensive tools. We hope that constructing and using these homemade tools will be an interesting, instructive, and enjoyable way for landowners to fulfill some of their forest inventory needs.

By Donald P. Hanley, WSU Extension Forestry Professor Emeritus, and J. Alan Wagar, Forestry Professor Emeritus, University of Washington.

Copyright 2011 Washington State University

(condensed by Carol Mack from the orginal article (Download the complete article.)