Adopt a Tree Diameter (DBH)

Created by John Pickle, DEW Educator, Arlington, MA

  • 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.
  • DBH serves as a yearly measure to help characterize the growth of trees in your Picture Post pictures. Measurements must be taken at exactly the same height on the trunk each year. Otherwise, you will find that their tree diameters may shrink or make inaccurate jumps in width from year to year!
  • The pictures show ways to add a known object to a picture for later use in measuring DBH.
  • Your Picture Post pictures will always be taken from the same spot, so you will only need to add an object in one picture: as the tree grows and the DBH expands, you can easily measure the change between pictures.

Step-by-Step instructions for measuring tree diameter (PDF) using your Picture Post
and the Analyzing Digital Images (ADI) software.

dbh measurements
measuring big DBH