Logging Advisor
 Home
 Standards
 Glossary
 User Guide

Special Techniques for Felling Difficult Trees

fellingagainstlean1
A large tree may be felled against its natural lean by inserting one or more wedges in the back cut.  As the back cut is sawn, the wedges are driven in with an axe.

The amount of back lean that can be overcome is based on the height and diameter of the tree to be felled. The following method determines the amount of back lean which can be overcome with 2 inches of wedging.

Wedging Trees with Back Lean
Trees that side scar easily
Larger Trees
Heavy Leaners
Trees leaning the wrong way

The following are unacceptable practices:
Wedging Trees with Back Lean
  • Determine the height of the tree. This can be estimated quite accurately using one of these methods:
    • Pro-Sight method
    • Clinometer method
    • Axe handle method
  • Determine the diameter (not circumference) of the tree at breast height using a tape.
  • Determine the number of segments in the tree by dividing the height (in feet) by the diameter (in feet).
    • Example: a 100 foot tree 24 inches in diameter (2 feet) would yield 50 segments (100 ÷ 2).
    • Example: a 100 foot tree 12 inches in diameter (1 foot) would yield 100 segments (100 ÷ 1).
  • Determine the amount of back lean (in feet) by plumbing the tree.
  • Use the following table to determine the maximum amount of back lean that can be corrected with 2 inches of wedging.

# of Segments

Maximum amount of back lean which can be overcome with 2" wedge

30

4 feet

35

4 1/2 feet

40

5 1/2 feet

45

6 feet

50

6 1/2 feet

55

7 feet

60

8 feet

65

9 feet

70

9 1/2 feet

75

10 feet

80

11 feet

90

12 feet

100 or more

13 feet

Trees that side scar easily
sidescar1
1. In standard felling, the sides of the hinge between the notch and the back cut are not sawn when the tree starts to fall.
sidescar2
2. As the tree falls, there is strain on the sides of the tree along the dotted lines. (circled area)
sidescar3
3. Instead of breaking with the hinge, strips along the side of the tree rip off the stump, resulting in side scars.
sidescar4
4. To prevent side scarring, corner to a depth of one inch before making the back cut.
Felling Larger Trees with slight lean or with heavy tops.
largertrees1
The notch is made in the normal manner (1/3 dia. of tree).
largertrees2
Make corner cuts.
largertrees3
The number one cut is made as per the diagram, at the same height above the notch as a standard back cut.
largertrees4
The number two cut is made as per the diagram, at the same plane as cut number one.
largertrees5
The number three cut is made at the same plane as the former cuts, leaving the standard thickness of hinge.
Heavy Leaners (The boring technique)
heavyleaners1
Begin by making a shallow notch (1/4 dia. of tree)
heavyleaners2
Next, holding the saw bar horizontal to the plane of the notch and at a slightly higher plane, the tree is bored out cutting back from the notch, leaving a good hinge and sufficient holding wood.
heavyleaners3
The same boring procedure is then performed on the other side of the tree, ensuring that the two boring cuts meet properly.
heavyleaners4
Then a back cut is made horizontal to the boring cut, a minimum, of two inches below the boring cut; the holding wood at the back severs and the tree falls, guided by the hinge.
Trees leaning the wrong way
Most trees will fall on the branch heavy side or in the direction of their lean; some trees can be encouraged to fall to the right or left of their lean, the extent varying with every tree. 

Two techniques can be used to control the direction of fall; they can be used individually or together.

leaningwrongway1
1. The notch must be made in the desired direction of fall; by varying the thickness of the hinge on one side and cornering the lighter side, you change the direction of fall.
leaningwrongway2
2. The notch is made in the desired direction of fall, a hinge is left and a corner cut (No. 1); a wedge is hammered into the back cut or a felling bar is used, forcing the tree to fall in the desired direction.
 

 

Back Back

tracking image