Measure the diameter at breast height (DBH) for the trees in the pictures below. Note: The clipboard is 9 inches wide and the location to measure is across from the bottom of the clipboard.
Background information about DBH from the Forest Watch protocols:
Foresters use a measurement of a tree’s diameter called DBH or diameter at breast height. Tree diameter
is an important forestry measure and is used to indicate how well a tree is growing over time. It is also
one of the standard measures of timber volume used to estimate the commercial value of a forest stand.
By convention, the diameter is measured at a height on the trunk that is 1.35 m (4.5 ft) above ground
level. This height above the ground is used because uneven swelling and irregular growth at the base of
the tree and upper roots could mask the true growth of the trunk.
For the Forest Watch study, DBH will serve as a yearly measure to help characterize the growth of your
white pine trees. Measurements must be taken at exactly the same height on the trunk each year. Otherwise,
teachers and students will find that their tree diameters may shrink or make inaccurate jumps in
width from year to year!
Download the images of the trees below and use in the AnalyzingDigitalImages software.
Use the "Spatial" window and select the "Line" tool to measure the tree diameter.
To download the image, either right-click or click and hold on the image. A pop-up menu will have the option to 'Save Image As...', which allows you to save the image on your computer.
You may do this to download most images available on the Internet.
See the Manual and Help Files on AnalyzingDigitalImages for guidance.
AnalyzingDigitalImages is available in the DEW software bundle.