How to Measure a Big Tree

Step 1. Calculating Tree Measurements In The Field

The following measurements are taken:

1. Height (Diagram 1): Total height of tree as shown on diagram. In the case of a broken top, the height to this point is also of interest. For the large coniferous trees, height to first branch is of interest. Measurement is by clinometer, Abney level or other suitable sighting instrument with measurements from several different points ensuring accuracy for the taller trees.
    
2. Circumference (Diagram 2): Circumference is measured at breast height (B.H.) 1.37 m above ground level. The diagram shows measurement locations in the case of slope. If a low branch, fork in trunk or burl makes this location unsuitable, measure at most suitable point above or below the obstruction. Give measurement location if not at breast height.
    
3. Crown Spread (Diagram 3): This is the average crown diameter (the distance across the branches). Measure the widest and narrowest points and divide by two to obtain the average.

Step 2. Calculating Points

1. Using Imperial measurements:

   Height - 1 point per foot
   Circumference - 1 point per inch
   Crown Spread - 1 point per four feet

2. Using metric measurements:

   Height - 3.2808 points per metre
   Circumference - 0.3937 points per centimetre
   Crown Spread - 0.8202 points per metre