Strandgard M., Mitchell R., Acuna M. (2017): Time consumption and productivity of a forwarder operating on a slope in a cut-to-length harvest system in a Pinus radiata D. Don pine plantation. J. For. Sci., 63: 324-330.Time consumption and productivity of a Valmet 890.3 8 wheel forwarder were evaluated on an Australian radiata pine clearfell site with a slope of 21 to 45% (12 to 24°). Cycle time was significantly related to extraction distance. Productivity was significantly related to extraction distance and load volume. Slope did not have a significant effect on cycle time or productivity. Productivity was considerably greater than that for many published studies, which was likely to have been the result of many factors at the study site affecting load sizes and cycle times, including the large load capacity of the studied forwarder, larger mean log volumes, larger log volumes per loading stop, fewer log assortments, potentially larger forwarder grapple volume capacity, log lengths suited to efficient loading and higher travel speeds.

Background: Forest biomass is a major global source of biofuel. To compete with other energy sources its delivered costs need to be reduced. Globally, logging residue (LR) is likely to be the cheapest, readily available forest biomass form. LR transport is a major cost component. Methods: A harvester-forwarder harvest system was studied in two adjacent areas to compare Swedish “fuel-adapted harvesting” with conventional cut-to-length harvesting at the stump in a mature Pinus radiata D.Don plantation in Western Australia to assess the impact of fuel-adapted harvesting on costs and productivity of a harvester and forwarder producing logs and extracting LR and on LR yield. Results: Harvester and forwarder productivities producing logs were significantly reduced in the fuel-adapted area compared with the conventional area which increased log production costs for the fuel-adapted site by 15%. Forwarder productivity extracting LR and LR yield were significantly greater in the fuel-adapted area which reduced LR extraction costs by approximately 28%. This was due to the ease of loading LR from residue piles created during fuel-adapted harvesting compared with loading scattered residue from conventional harvesting. The cost reduction for LR extraction from the fuel-adapted area exceeded the increased log harvest and extraction costs. This resulted in the combined log and LR costs for the fuel-adapted area being approximately 12% lower than those for the conventional area. Increased forwarder productivity through adoption of larger load bunks and residue-specific grapples combined with increased operator experience with fuel-adapted harvesting would be likely to further decrease log and LR production costs. Conclusions: The results show that adoption of fuel-adapted harvesting could reduce LR delivered costs, thus increasing its viability as a biofuel. However, primary transport cost is only one component of LR delivered costs and needs to be considered in combination with the reduction of other supply chain costs, particularly secondary transport costs which can make up a large proportion of LR delivered costs. Because removal of most LR from a site can reduce subsequent tree growth, guidelines specifying the proportion of LR retained should be considered.

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The cost of harvesting short-rotation plantation eucalypts can be in excess of AU$2500·ha−1. Despite this high cost, the extent to which harvesting productivity is affected by tree genetics is not well understood. We address this issue in a study of two 10-year-old genetic field trials of Eucalyptus globulus Labill. in Australia. Standing-tree traits analysed were survival, diameter at breast height, basal area, and stem straightness and forking. Harvest traits analysed were volume, time, and productivity. Genetic group and within-group genetic variation (additive and dominance), stand-level family variation, phenotypic and genetic correlations, and the effects of inbreeding were estimated for these traits. The different scenarios studied showed that plantation harvest productivity was affected by tree genetics to some degree but was mainly affected through positive covariation with stem diameter. Harvest productivity is thus unlikely to have been adversely affected by past selection. Although no significant additive or dominance genetic variation in stem forking or straightness was detected, weak phenotypic correlations were consistent with harvest productivity being higher in straighter trees with no forking. High inbreeding depression was evident for growth and survival; however, in open-pollinated progeny, this resulted in only a slight reduction in harvest productivity (5.5%) compared with out-crossed progeny.

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A chain-flail delimber-debarker-chipper (CFDDC) was adapted for treating smaller trees than normal by replacing the standard flails with lighter ones, and by reducing flail drum rotation speed. The machine produced 16 full containers (24 t each) for the standard configuration and 24 full containers for the innovative one. For each container the researchers measured: original tree mass, chip mass, time consumption and fuel use. Results indicated that the innovative setting accrued a 12% improvement on fiber recovery compared with the standard setting (control). At the same time, productivity increased by 20% and fuel consumption was reduced by 30%. Product quality was largely unaffected, with bark content remaining below the 1% threshold specification. If at all, product quality was improved through the reduction of fine particles, possibly derived from less diffused fraying. These results have triggered the real scale adoption of the new setting by contractors who participated in the study. The success of the innovative treatment is likely explained by its better alignment with the weaker structure of small trees from low-yielding stands.

Abstract:The impact of the manipulation of plantation stocking density on individual tree size can affect final harvest costs and machine productivity. This paper investigated the impact of four early-age thinning treatments applied to a Eucalyptus globulus Labill. pulplog plantation in south-west Western Australia on economic profitability and harvester productivity. Eighteen sample plots were randomly laid out in the study area. The nominal 700, 500, and 400 stems per hectare (sph) plots were thinned to waste 3.2 years after establishment while the nominal 1000 sph (UTH) plots were left unthinned. The economic analysis showed that all thinning treatments resulted in a lower Land Expectation Value (LEV) and net financial loss over the full rotation at their theoretical optimal rotation age when compared with the unthinned control treatment. Tree growth and form were positively impacted by thinning. However, associated reductions in harvesting costs were less than the value losses resulting from reduced per hectare yield.

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