Skip to main content
Report, 2010

Estimates of the productivity of logging operations with a focus on forest fuel extraction

Sängstuvall, Lars


Over recent years, as a result of energy policy at global, European and national levels, the prices and demand for bio-fuel, including forest fuel, have increased. This has lead to reductions in the marginal profits associated with the use of a range of forest fuel assortments. New and improved methods and techniques for extracting logging residues, stumps and whole-trees from young stands are therefore currently being investigated. Unlike final felling, revenues from forest fuel extraction during thinnings are expected to be of about the same magnitude as the revenue from thinning or the cost of pre-commercial thinning. This will probably influence the timing and type of all forest management activities throughout the rotation period of a stand. When estimating logging potential, forest management is simulated on the basis of assumptions about the forest and the behavior of the forest owner. Priority can be given to forest characteristics, economic or ecological aspects when specifying treatment variables and models can also incorporate probability functions for land owner behavior. Management simulations result in an estimate of the logging potential for the forest area at hand. Forest fuel logging potential is usually derived by appending forest fuel extraction to the roundwood extraction treatments, also taking into account economic and ecological constraints specific for the forest fuel extraction. In order to estimate the harvestable volume based on economic, ecological and practical criteria we must have some measures of the properties and influence of these criteria. This essay reviews productivity studies that could be of use when modeling thinning and forest fuel operations in Swedish forests. Furthermore it pinpoints areas of insufficient knowledge with respect to the productivity of forest fuel extraction from young forests. In the case of such young stands, there is practically no information about land owner behavior, and any logging potential estimates would currently have to rely on some kind of simulation based on a specific forest management goal. Assuming that forest fuel extraction affects forest management, the accuracy of estimates would be improved if such operations were modeled accurately and fully incorporated into the ordinary logging potential estimate. Comparative and correlation time studies are commonly used in forestry to evaluate the performance of different systems or techniques or to evaluate and price different working units within a system or technique. For roundwood logging, both the single-grip harvester and the forwarder are established technological systems, and hence there are many correlation time studies quantifying time consumption in different working environments for these systems. Whole-tree or tree-section logging, particularly in young forests, has been little used in Nordic forestry and hence most time studies that are available are comparative. The properties and influence of forest fuel harvesting in young stands therefore needs to be further investigated. This will ensure appropriate estimates of the amount of forest fuel that can be derived from young stands and will facilitate long-term forest management planning with forest fuel extraction included as a treatment. Harvesting productivity, expressed as number of trees processed per time unit, decreases with increasing tree size and for more processed, e.g. delimbed, assortments. Forest haulage productivity decreases with, among other variables, increasing transportation distance, decreasing load size, and decreasing grapple size. A theoretical, partially deductive, framework for the time associated with forwarding has been adapted to the specific environments described in a number of studies. Comparing the calculated time consumptions with the actual results from the studies shows that the theoretically-based time consumption model has a high level of accuracy. This indicates that the time consumption for forwarding under defined working conditions (e.g. pile size, proportion of solid volume) not yet studied or experienced can be modeled in advance with acceptable accuracy. A few questions still remain with respect to the way to adapt the theoretical model to specific situations, since different approaches seemed more or less successful in different cases


harvesting; logging potential

Published in

Arbetsrapport / Sveriges lantbruksuniversitet, Institutionen för skoglig resurshushållning
2010, number: 297
Publisher: Institutionen för skoglig resurshushållning, Sveriges lantbruksuniversitet

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Resource Management

UKÄ Subject classification

Forest Science

URI (permanent link to this page)