Faculty of Forestry and Wood Technology, University of Zagreb
Abstract
Motor-manual tree felling is the most labor-intensive component of all harvesting operations and frequently represents a bottleneck in wood production. The study of motor-manual tree felling was carried out in two compartments in the Namkhaneh district of Kheyrud Forest. The objects of this study were as follows: time study of tree felling operations, estimate of chainsaw productivity and costs, development of a regression model in uneven-aged stand using single-tree selection methods. The factors affecting total felling time regression model (increasing order of importance) were DBH of harvested trees, direction of felling regarding the lay and inter-tree distance. The hourly production of chainsaw felling with and without delay time was 56.4 cubic meters per hour (13 tree/hour) and 80.7 cubic meters per hour (19 tree/hour), respectively. Productivity of chainsaw felling increased in relation to tree DBH as power relation. The cost of chainsaw felling with and without delay time was 0.55 and
0.39 USD/m3, respectively. The cost of felling increased as simple exponential equation when DBH of harvested trees decreased. However, the unit felling cost for chainsaw operation decreased as the tree size increased. Total felling cycle time without delay averaged 3.14 minutes and with delay time it averaged 4.5 minutes. Productivity was more sensitive to DBH than felling direction and inter-tree distance
