2017 Volume 32 Issue 1 Pages 15-
The traction force for removing hung-up trees and the resistance force of crowns was measured in the crowns of two trees by skidding toward the felling direction with upward felling in a steep Chamaecyparis obtusa stand. The average maximum vertical component (Tr1.2) of the traction force at a height of 1.2 m from the butt end was 6.76 kN, and the average resistance force of the crown (FA) was 1.1 kN. No strong correlation was observed between the interval of the remaining two trees (D) and the Tr1.2 or FA value. A power relation was shown between the overlap ratio of the crown (Rc) and the FA. The upper limits of the Tr1.2 and FA values were expected according to the D value. Compared to other studies, the values of the upward felling and traction force toward the felling direction found in this study was greater than the downward felling and traction force toward the felling direction. The latter were approximately equal to those of the downward felling and butt-end traction but were greater than the ones of the upward felling and butt end traction. Our results demonstrate the difficulty of manpower methods using rope-based stem traction toward the felling direction and butt-end traction in the direction opposite to felling.
