Nowadays the majority of the thinnings made in Swedish forests are done by machines, harvesters and forwarders. The most common model in thinning with a harvester is strip-road operated thinning and stand-operated thinning with one intermediate passage between the strip-roads. This study is a time study with some quality follow ups on a strip-road operated thinning model, a stand-operated thinning model with one intermediate passage between the strip-roads and a stand-operated thinning model with two intermediate passages between the strip-roads. The machines in the study were a small harvester (Forestline MPM C90) and a medium sized forwarder (Timberjack 1110).
The study was made in Litsnäset outside the city of Östersund in Sweden and was made during the autumn 2007. In a lodgepole pine stand six study units (0,6 ha) were thinned with the three different models, two study units per model. After the thinning was done two loads of timber per study units were forwarded out.
The results of the study showed that the performance of the harvester was similar when working with the stand-operated thinning models compared to the strip-road operated thinning model. The difference in performance between the three types of thinning models was not significant. The results for the forwarder showed that the difference in performance was significant between the models that were thinned with the stand-operated models and the strip-road operated model and it performed by far best in the model that was thinned with the stand-operated thinning with two intermediate passages between the strip-roads.
The quality follow up showed that the strip-road operated thinning model left fewer damaged trees in the remaining forest than the other two stand-operated thinning models. However, the stand-operated thinning models had a smaller strip-road area.
The financial analysis showed that the cutting costs for both machines were ...
