Efektywność pozyskiwania drewna harwesterem w młodszych trzebieżowych drzewostanach sosnowych w zależności od technologii pracy

In Poland, more and more timber is harvested with the use of harvesters of different types. These machines can also be used in cooperation with chainsaw operators, e.g. in stands damaged by violent winds, in the removal of windthrows, or in stands of younger age classes in the technological variant with the so-called „midfield”. The aim of the study was to characterise the working time structure and to estimate the efficiency of timber harvesting with a harvester in two technological variants. In the first variant, the felling of trees was carried out by a chainsaw operator and the processing was performed by a harvester operator. In the second variant all operations were carried out by a harvester operator. In both variants, the machine worked on the skid trails, but in the second variant, the operator descended from the skid trails a short distance into the stand. Harvesting was conducted in two pine stands that were approximately the same age and differed in site conditions. The structure of the harvester operator's work time was clearly dominated by the moving of felled trees to the skid trails in both variants. Of all the activities studied, the observed differences between their durations in both variants were insignificant only in the case of delimbing and bucking (processing). In the case of cooperation between harvester operator and chainsaw operator, a higher work efficiency was achieved than in the case of timber harvesting with a harvester alone. At the same time, significantly lower work time consumption was observed. However, when considering the efficiency of the entire technologies, thinning with two workers was 30-60% more time consuming. Significant relationships were found between the amount of merchantable timber of harvested trees and the efficiency of the harvester operator.