Pine and spruce stump harvesting productivity and costs using a Pallari KH 160 stump-lifting tool

Abstract

Even though stumpwood may become a significant part of the future fuel mix for combined heat and power plants in Sweden the harvesting of stumps after regeneration fellings is still only performed on a trial basis. Results from time studies on two, 23 tonne, excavators fitted for stump lifting; together with followup data on stump lifting and forwarding are presented. Lifting, splitting and piling the stumps accounted for 17 %, 32 % and 32 %, respectively, of the total productive work time. A predictive model was developed to estimate operational times and productivities when lifting pine and spruce stumps. Stump diameter, species and terrain conditions contributed significantly to the fit of the model. The model predicts that productivity of stump lifting in spruce sites with easy terrain conditions and average stump diameters of 20 and 40 cm will be 1.23 and 4.19 oven-dry tonnes (ODT) per productive work hour respectively. This is 43% higher than in pine sites with difficult terrain conditions and the same diameters. In the follow-up data the productivity in stump lifting varied from 1.5 to 2.9 ODT per productive work hour while the cost for lifting and extraction to roadside varied from 37.8 to 59.4 € per ODT.

Comparison of two stump-lifting heads in final felling Norway spruce stand

“…The size of material was relatively large comparing to the study materials of earlier lifting studies (e.g. von Hofsten and Nordén 2007, Karlsson 2007, Hedman 2008, Laitila et al 2008, Jouhiaho and Mutikainen 2010, Jouhiaho et al 2010, Laitila 2010, Athanassiadis et al 2011, Erkkilä et al 2011. The study data was collected from only one excavator, which operated only one driver in two time study stands located in easy terrain.…”

“…Recent stump-lifting studies have demonstrated that the productivity of pine stump lifting is lower than in spruce stump lifting (e.g. Karlsson 2007, Hedman 2008, Lazdiņš et al 2009, Jouhiaho and Mutikainen 2010, Athanassiadis et al 2011, Erkkilä et al 2011.…”

“…Spinelli et al 2005, von Hofsten and Nordén 2007, Karlsson 2007, Laitila et al 2007, 2008, Hedman 2008, Laurila and Lauhanen 2008, Lazdiņš et al 2009, von Hofsten 2010, Jouhiaho and Mutikainen 2010, Jouhiaho et al 2010, Laitila 2010, Athanassiadis et al 2011, Erkkilä et al 2011, Tolosana et al 2011). Besides, the issue is very important, as the Väkevä Stump Processor is the most commonly used lifting head in Finland.…”

“…In addition to Scots pine stumplifting time study with the tested lifting heads, further long-term follow up studies with stump harvesting are needed. Previously, only Jalava (2007) and Athanassiadis et al (2011) (based on Hedman 2008) have conducted follow up study of stump lifting. When investigating the study results, it must be recognized that it is extremely difficult to compare stump-lifting productivity data from various studies directly.…”

Technology and energy balance in stump harvesting with MCR500

“…To get stump parts clear of soil particles and stones, shaking of each piece is needed after it has been lifted above the ground level. On the research basis of this technology the figures on the productive work time distribution show that 17 % of the work time has been spent for lifting, 32 % -to split stumps, and the same amount of time -to put the stumps into a stack [6]. Created in Latvia prototype of the stump-lifting bucket MCR500 encompasses both an apparatus for stump uprooting and a device for soil scarification before forest planting.…”