Comparison of damage to residual stand due to applying two different harvesting methods in the Hyrcanian forest of Iran: cut-to-length vs. tree length

Abstract

Damage to residual stand is unavoidable and it is one of the main important issues in the forest harvesting. Trees damage may occur in felling and skidding work phase or during skid trail construction. In any case, damage can be very serious to residual stand. Detailed study is necessary to find out the amount and severity of damage to trees; therefore district 14 of Kilesara in Guilan Province, Iran was selected for the study. The cut-to-length and the tree - length methods are practiced in the Hyrcanian forest. Applying any of these two methods is mostly related to dimensions of woody material, technical characteristics of skid trail, and machinery availability. A residual stand which is left after practicing such a method, is damaged in different way which needs to be studied in detail. The length of the winching strips and skid trails differed, but the width of them was kept constant at 6 m (3 m distance from centerline of winching strips or borderline of skid trails). All trees and regenerations around winching strips and skid trails are investigated for finding any sign of damage or injuries. The results showed that along winching strips, the percentage of damage to the residual stand was 19.5 and 18 %, while the damages along skid trails reached 25.4 and 31 % in the tree length and cut-to-length methods, respectively. The results of this study suggest that damage to the residual stand is considerable and should be reduced in order to improve the quality of stand at future.