Forest Mensuration. Brack and Wood

General instructions

1. Select a distance, preferably 15, 20, 25, or 30 meters away from the tree, where the required point on the tree (e.g. tree tip) can be seen. Measure the selected horizontal distance from the base of the tree (or the position directly beneath the required point).
2. Select the appropriate distance scale on the rotating rod.
3. Release the pointer by pressing the button on the side of the instrument.
4. Sight at the required point on the tree, wait for a moment for the pointer to settle then pull trigger.
5. Read the height directly from the appropriate scale if you are 15, 20, 25, or 30 meters away from the tree. If you were unable to find a position at one of these distances:
   • If the horizontal distance is a simple fraction of one of the scale distances (e.g. 10 m is half of 20 m), read from the scale distance and multiply by the appropriate fraction.
   • Read from the percent scale and multiply this percentage by the horizontal distance measured in step 1.
6. Site to the base of the tree and repeat steps 3 - 5.
7. Combine the heights from steps 5 and 6 to determine total tree height:
   • Add the 2 heights together if you looked up to the required point in step 3 and down to the base of the tree in step 6.
   • Subtract the height to the base of the tree from the height to the required point if you are on sloping ground and had to look up to both the required point and the base of the tree.
8. Check all readings and calculations.

http://online.anu.edu.au/Forestry/mensuration/HAGA.HTM
Cris.Brack@anu.edu.au
Fri, 6 Jun. 1997