Appendix 1 spacer How to Measure Tree Height Using a Suunto and Distance Tape
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Lesson 1
Lesson 2
Lesson 3
Lesson 4
Lesson 5
Lesson 6
Lesson 7
Lesson 8
Lesson 9
Lesson 10
Lesson 11
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Appendices
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Appendix 9
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Very briefly, here is one way to measure tree height with a suunto and distance tape.

  1. On the sample tree, accurately locate 1.3 m above ground on the high side. This is breast height (bh).
  2. Attach the logger's chain at the centre of the tree at bh or have a crew member hold the end of the distance tape at this point.
  3. Walk back from the tree to a location where you can see both the top of the tree and bh It is often best to go uphill of the tree. Pull the tape tight and straight between the tree and your eye. With the suunto, read the % to tree top. If the reading exceeds 100%, move further away from the tree and repeat. If the tree has a droopy leader, shoot to the top of the droop.
  4. Then, from the same location, read the % to bh with the suunto.
  5. Record, top shot (% to top), bh shot (% to breast height), slope distance, and bh correction (1.3 m).
  6. Calculate horizontal distance using Table 1 or other slope tables. To use Table 1, multiply slope distance by the appropriate factor to get horizontal distance.
  7. Combine top and bh shots. If the bh shot is negative, treat both numbers as positive and add top and bottom percents (i.e., +88% top shot, -10% bh shot, combined percentage is 98%). If the bh shot is positive, subtract bottom from top (i.e., +88% top shot, +10% bh shot, combined percentage is 78%).
  8. Multiply the combined percent by the horizontal distance. This produces tree height above bh. Add the bh correction (1.3 m) to produce total tree height.
  9. For the growth intercept method, if the tree has a droopy leader, add to the calculated height the amount required to obtain total tree height with the tip straightened up.

Table 1. To get horizontal distance, multiply slope distance by this factor.

Percent to bh (%) Factor Percent to bh (%) Factor Percent to bh (%) Factor Percent to bh (%) Factor
1 1 26 0.968 51 0.891 76 0.796
2 1 27 0.965 52 0.887 77 0.792
3 1 28 0.963 53 0.884 78 0.789
4 0.999 29 0.960 54 0.880 79 0.785
5 0.999 30 0.958 55 0.876 80 0.781
6 0.998 31 0.955 56 0.873 81 0.777
7 0.998 32 0.952 57 0.869 82 0.773
8 0.997 33 0.950 58 0.865 83 0.769
9 0.996 34 0.947 59 0.861 84 0.766
10 0.995 35 0.944 60 0.857 85 0.762
11 0.994 36 0.941 61 0.854 86 0.758
12 0.993 37 0.938 62 0.850 87 0.754
13 0.992 38 0.935 63 0.846 88 0.751
14 0.99 39 0.932 64 0.842 89 0.747
15 0.989 40 0.928 65 0.838 90 0.743
16 0.987 41 0.925 66 0.835 91 0.740
17 0.986 42 0.922 67 0.831 92 0.736
18 0.984 43 0.919 68 0.827 93 0.732
19 0.982 44 0.915 69 0.823 94 0.729
20 0.981 45 0.912 70 0.819 95 0.725
21 0.979 46 0.908 71 0.815 96 0.721
22 0.977 47 0.905 72 0.812 97 0.718
23 0.975 48 0.902 73 0.808 98 0.714
24 0.972 49 0.898 74 0.804 99 0.711
25 0.97 50 0.894 75 0.800 100 0.707

Example:

Percent to top: +75%
Percent to breast height (bh) -15%
Slope distance 20 m
Breast height correction 1.3 m
Horizontal distance
     = slope distance x factor
     = 20 x 0.989
     = 19.78 m
 
Combined percent
     = top shot + bh shot
     = 75 + 15
     = 90%
 
Height above bh
     = horiz. distance x combined percent
     = 19.78 x 0.9
     = 17.80 m
 
Total height
     bh correction+height above bh
     = 1.3 m + 17.80 m
     = 19.1 m
 

 

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