How to Measure Trees

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1. Measure Circumference

   Tree circumference is measured at 4.5 ft. height on the trunk. It is easiest to measure with a flexible tape measure, but a string can be used to mark the circumference and then measured with a ruler or rigid measuring tape. Wrap the tape measure around the girth of the tree, trying to keep the tape 90 degrees to the natural lean of the tree.

   

2. Measure Height

   Method 1 –Using a clinometer

   If you have a clinometer, and don’t mind doing a little math, this method is more accurate for determining tree height. Stand a distance back from the tree at a point where you have a good view of the crown. Use the clinometer to determine the angle from your position to the highest point on the tree. Then, using a measuring tape, measure the distance from your location to the trunk of the tree. Use the following equation to calculate the height, you will need a calculator to find the tangent of the angle reading from the clinometer and multiply this value by the distance to the tree trunk. Finally, add your height to result to find the final tree height.

   Height= tangent (clinometer angle) x distance to tree trunk

   Final tree height= height + recorders height

   

   Method 2- Using a ruler

               Stand a distance away from the tree where you can see the entire tree in your field of view. Hold the ruler upright in your hand with your arm extended out fully. Line the ruler up with the tree so the top of the ruler aligns with the highest point of the tree; mark on the ruler with your thumb the tree base. Keeping your arm extended, turn the ruler 90 degrees. Either have your measuring assistant stand at the point on the ground out from the tree where you see the ruler end or note the point where the ruler ends. Measure the distance from either the person or the spot to the tree base, this distance is equivalent to the trees total height.

   

3. Measure average spread

   To measure the spread of a trees’ crown, have two people stand at opposite extents of the crown directly under the furthest extent of growth. Measure the distance between the two using a measuring tape. A minimum of two measurements are need to determine the average spread, typically you will use the distance of the widest part of the crown and the distance of the shortest part of the crown.