Productivity and costs of the mechanised cut-to-length wood harvesting system in clear-felling operations

Abstract

A study of labour productivity was conducted in fully mechanised harvesting technologies. The study revealed that the productivity of harvesters was particularly affected by the average tree volume of the felled trees, and the productivity of forwarders was affected mainly by two factors -haulage distance and machine payload. Dependences of other factors such as natural and site conditions, technical parameters and skills of operators could not be demonstrated. Regression equations of dependences were created for all these three significant criteria and costs per cubic meter of processed timber were calculated for them according to the cost function. A regression function was then developed for the forwarder that takes into account both significant criteria influencing the forwarder productivity. Mechanised cut-to-length (CTL) wood harvesting methods have become widely used in many industrialised European countries such as Sweden (ca. 98%), Ireland (ca. 95%) and Finland (ca. 91%) compared to motor-manual harvesting (Karjalainen et al. 2001). During the last two decades the mechanisation of working processes in forestry has increased rapidly. Due to labour shortage and the need for economical wood production, a lot of developments were made towards rationalisation especially in harvesting (Schaeffer et al. 2001). The CTL system requires less labour, less road construction, and fewer landing areas than the other ground-based systems (Bettinger, Kellogg 1993).Productivity of the CTL system depends on the forest stand, site and operational factors such as ground conditions, slope, operator's motivation and skill, branch size, operational layout, tree size, tree form, log assortments processed, numbers of unmerchantable and merchantable trees per unit area, hauling distance, undergrowth density and machine design (Brunberg et al. 1989;Spinelli et al. 2002;Stampfer 1999;Makkonen 1991;Richardson 1989). Harvester productivity is closely related to the tree size and stand characteristics (Bulley 1999).The aim of this study was to generalise productivity trends of different machine classes and to show general trends of productivity in relation to the most demanding factors in clear-cutting operations and to determine the operation cost for different harvester and forwarder classes. MATERIAL AND METHODSAltogether 21 field studies for harvester and 8 field studies for forwarder were carried out. Both types of purpose-built and excavator-based machines were investigated. In harvesting operations 15 different machines were studied, out of which 12 were excavator-based and 3 purpose-built harvesters, and in hauling operations 7 different machines were studied, out of which 1 was excavator-based and 6 purpose-built forwarders.The experiments were carried out in standard working conditions typical for Ireland. The average tree size varied between 0.1 m 3 and 1.0 m 3 and the hauling distance varied from 80 to 1,400 m. All the

Evaluation of Salvage Logging Productivity and Costs in Windthrown Norway Spruce-Dominated Forests

“…When comparing the cutting productivity of normal standing trees in this study to the cutting productivity of Norway spruce in the study by Nurminen et al [76], it is noted that the cutting productivity in this study was higher when the stem size of removal was <0.76 m 3 (Figure 8), and the opposite was found with larger spruce stems. The cutting productivities reported by Brunberg [81], Jiroušek et al [82] and Eriksson and Lindroos [62] are also quite close to the average cutting productivity level in the normal clear cuts in this study (Figure 8).…”

“…The cutting productivities reported by Brunberg [81], Jiroušek et al [82] and Eriksson and Lindroos [62] are also quite close to the average cutting productivity level in the normal clear cuts in this study (Figure 8). Hence, on the basis of the results of this study, it can be concluded that a big leap has not necessarily been taken in the development of forest machine technology during the last ten years.…”

Value Retention, Service Life, Use Intensity and Long-Term Productivity of Wood Chippers as Obtained from Contractor Records

“…Since the exponent is larger than 1, the curve bends upwards and describes the typical phenomenon of increasing returns, which in this specific case has been interpreted as the scale effect of engine power. Conversely, curves relating productivity to piece size use exponents smaller than 1 and bend downwards, indicating diminishing returns as piece size increases [26]. That is important to notice, because it demonstrates that productivity is directly proportional to both engine power and piece size, and yet investments in engine power are more productive, as returns are higher and may easily offset limitations in piece size.…”

Industrial Round-Wood Damage and Operational Efficiency Losses Associated with the Maintenance of a Single-Grip Harvester Head Model: A Case Study in Russia

“…When buying a whole harvester or a harvester head for the available base machine (the excavator, for instance), the technical features of the equipment should fit operational conditions to avoid unnecessary impairment of its effectiveness. Many developments have been made towards improvement of fully mechanized CTL in the field of harvester productivity and costs [1,[7][8][9][10][11][12], which are dependent upon the silvicultural system, operational phase, ambient temperature, outcome product, stand factors, operator factors and machine factors, terrain and climatic conditions, as well as growing stock per hectare according to a region [13].…”