Martin Strandgard

Estimating harvester productivity in Pinus radiata plantations using StanForD stem files

Abstract Productivity models produced using time differences between consecutive StanForD stem files collected by harvester onboard computers were compared with models produced using traditional time and motion techniques for the same initial trees. Three sites were studied in Pinus radiata plantation clearfell operations across southern Australia. Delays and trees with multiple leaders or broken tops were removed from the data. This was done for the stem file data using filters. The same filters were applied to data from all sites. No significant differences were found between the models at each site, though the stem file productivity models generally had a poorer fit than the time and motion models. The advantages of using stem files for modelling are the ready availability of stem file data, which enables rapid creation of generalised harvester productivity models and avoids short-term changes in productivity caused by the presence of an observer (the “Hawthorne effect”). Disadvantages are the inability to account for unforeseen changes in conditions during data collection, and the inability to isolate work-cycle time-element data.

A log-by-log productivity analysis of two Valmet 475EX harvesters

Productivity of a mechanized harvesting system is influenced by stand and terrain conditions, operator performance, and machinery limitations or design. The purpose of the study was to compare the productivity of two near-identical single-grip harvesters in similar Australian Pinus radiata clearfell harvesting operations on a log-by-log basis. The study first compared the productivity of each harvester against tree volume for cycle times and for tree processing times only. Significant differences in productivity between the harvesters were found to be largely due to significant differences in tree processing times. Comparisons between each component of processing time (dragging-out time, disc-cutting time, cross-cutting time, harvester head travel time and delimbing time) for a subset of 6.1 m sawlogs at each study site found operator working technique differences to be the main driver of productivity differences between the harvesters. In particular, the operator of the less productive harvester dragged out most trees after felling and cut discs on most trees to reset the length-measuring device, whereas the operator of the other, more productive harvester rarely carried out these activities.

Improving the productivity of mechanised harvesting systems using remote sensing

Summary Mechanised harvesting operations are popular in Australia because of their productivity and efficiency, improved worker safety and reduced cost of operations. Most research has found that the productivity and efficiency of a mechanised harvesting system is affected by a number of factors such as forest stand characteristics, terrain variables, operator skill and machinery limitations. However, current studies did not quantify these factors sufficiently to evaluate the productivity and efficiency effects that can guide allocation of different harvesting equipment. This article reviews the literature on how major forest stand characteristics such as tree size and undergrowth affect the productivity and efficiency of a harvesting machine and/or system in clearfelling operations, and explores the application of remote sensing technology including multi-spectral imagery and LiDAR (light detection and ranging) to identify and quantify these characteristics to allow for better harvest planning and harvest system allocation. It is concluded that by evaluating the interactions between each of these factors and different types of harvesting equipment, an empirical model could be developed to optimise the use of current harvesting systems and assist the selection of more cost-effective harvesting machinery, using remote sensing.

Evaluation of the Hitman PH330 acoustic assessment system for harvesters

Reductions in Pinus radiata D. Don. (radiata pine) clearfell age have increased the juvenile wood proportion in sawlogs, increasing the need to segregate low modulus of elasticity (MOE) material early in the supply chain to avoid the costly processing of low-value, non-structural boards. In Australian radiata pine plantations, variability in MOE is greater between trees than between stands, requiring tests of individual trees to identify those with low MOE. Time of flight of a sound wave in a tree or log is known to be well-correlated to its MOE. The trial examined the ability of a newly developed acoustic assessment tool, the Hitman PH330 (PH330) supplied by Fibre-gen Limited, fitted to a harvester head, to identify and segregate low MOE sawlogs during a cut-to-length harvesting operation in a radiata pine plantation. The impact of using the tool on the harvester’s productivity was also examined. There was a reduction in the mean productivity of the harvester when using the PH330 compared with normal operations not using the PH330 but it was not significant. Mechanical MOE testing showed that boards cut from sawlogs which the PH330 identified as structural, had significantly greater mean MOE than boards from non-structural sawlogs, demonstrating the PH330 was able to separate high and low MOE sawlogs.

General productivity model for single grip harvesters in Australian eucalypt plantations

ABSTRACT Australia’s eucalypt plantation estate (>900 000 ha) has largely been established since 1995. The main species is Eucalyptus globulus producing wood chips for export on a short rotation (~10 years). Two main harvesting methods are used: cut-to-length (CTL) at the stump and infield chipping (IFC). CTL harvesting is typically carried out with single-grip harvesters and forwarders. The study objective was to develop a general productivity model for medium-sized single-grip harvesters performing CTL harvesting at the stump in short-rotation E. globulus plantations under typical Australian operating conditions, as few harvester productivity models have been developed for these plantations. The model was developed from 47 harvester productivity studies carried out in Australian E. globulus plantations. Studies were predominantly short-term counts of the trees cut over at least an hour multiplied by an estimate of mean merchantable tree volume derived from inventory plots measured where the harvester was about to work or an adjacent area. The model developed explained 80% of the variability in harvester productivity (79% was explained by mean tree volume and 1% by harvester engine power). Results from comparable published CTL eucalypt studies generally supported the model. The strength of the relationship suggests the model could be used to estimate harvester productivity for similar site conditions and harvester/harvester head combinations (which represent most Australian E. globulus plantations) where mean merchantable tree volume and harvester engine power were known or estimated.

Impact of number of stems per stool on mechanical harvesting of a Eucalyptus globulus coppiced plantation in south-west Western Australia

Coppice regeneration of eucalypt plantations is increasingly being used in Australia to reduce re-establishment costs. However, little is known about the impact of early coppice reduction regimes on harvester performance during clearfelling. The trial compared the productivity, time consumption, cost and fuel use of a single-grip harvester (Hyundai 210LC-9 base and SP 591LX harvesting head) clearfelling a 10.5-year-old, second-rotation coppiced Eucalyptus globulus stand in south-west Western Australia for chip logs. Coppice stems had been reduced to one stem or two stems per stool or left untreated. Time and piece counts were used to determine harvester productivity. Harvester cycle and elemental times and the number of logs and harvester head passes per stem were obtained from video recordings. Harvester fuel use was determined by refilling the fuel tank to the same point each day. Stem size was the major factor influencing harvester productivity (20.8 m3 per productive machine hour without delays [PMH0], 11.8 m3 PMH0−1 and 8.6 m3 PMH0−1 in the single-stem (mean stem volume [MSV] 0.21 m3), two-stem (MSV 0.09 m3) and untreated trial areas (MSV 0.06 m3), respectively. Estimated harvester cost (AU

Reconstructing the size of individual trees using log data from cut-to-length harvesters in Pinus radiata plantations: a case study in NSW, Australia

m–3) was considerably greater for the two-stem and untreated trial areas, which reflected the lower harvester productivity in these areas. Processing time represented over 60% of the total cycle time for all trial areas. Coppice characteristics resulted in significantly different moving/positioning times between trial areas. However, this difference had no impact on cycle times. Number of logs per stem was a significant variable in cycle and processing time regressions for all trial areas and felling time for the single-stem trial area. Number of harvester head passes was a significant variable in cycle and processing time regressions for the single-stem trial area and processing times for the two-stem trial area, although its effect was less than that of the number of logs per stem. Fuel consumption (L PMH0−1) was relatively constant between the trial areas, hence harvester energy intensity (L m−3) reflected the harvester productivity in each trial area.

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

With their widespread utilization, cut-to-length harvesters have become a major source of “big data” for forest management as they constantly capture, and provide a daily flow of, information on log production and assortment over large operational areas. Harvester data afford the calculation of the total log length between the stump and the last cut but not the total height of trees. They also contain the length and end diameters of individual logs but not always the diameter at breast height overbark (DBHOB) of harvested stems largely because of time lapse, operating and processing issues and other system deficiencies. Even when DBHOB is extracted from harvester data, errors and/or bias of the machine measurements due to the variation in the stump height of harvested stems from that specified for the harvester head prior to harvesting and diameter measurement errors may need to be corrected. This study developed (1) a system of equations for estimating DBHOB of trees from diameter overbark (DOB) measured by a harvester head at any height up to 3xa0m above ground level and (2) an equation to predict the total height of harvested stems in P. radiata plantations from harvester data. To generate the data required for this purpose, cut-to-length simulations of more than 3000 trees with detailed taper measurements were carried out in the computer using the cutting patterns extracted from the harvester data and stump height survey data from clearfall operations. The equation predicted total tree height from DBHOB, total log length and the small end diameter of the top log. Prediction accuracy for total tree height was evaluated both globally over the entire data space and locally within partitioned subspaces through benchmarking statistics. These statistics were better than that of the conventional height-diameter equations for P. radiata found in the literature, even when they incorporated stand age and the average height and diameter of dominant trees in the stand as predictors. So this equation when used with harvester data would outperform the conventional equations in tree height prediction. Tree and stand reconstructions of the harvested forest is the necessary first step to provide the essential link of harvester data to conventional inventory, remote sensing imagery and LiDAR data. The equations developed in this study will provide such a linkage for the most effective combined use of harvester data in predicting the attributes of individual trees, stands and forests, and product recovery for the management and planning of P. radiata plantations in New South Wales, Australia.

Productivity and cost of whole‑tree harvesting without debarking in a Eucalyptus nitens plantation in Tasmania, Australia

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.; ;

Improving harvester estimates of bark thickness for radiata pine ( Pinus radiata D.Don)

There is increasing interest worldwide in using tree harvesting biomass as an energy source. Bark retained on logs is commonly used as an energy source, but is generally removed from eucalypt logs during harvest. In order to evaluate the potential use of eucalypt bark as fuel, there is a need for information on the productivity and cost implications of retaining eucalypt bark during harvest operations. The study examined the impact of retaining bark on logs on the productivity and costs of a whole‑tree to roadside harvesting system in a short‑rotation Eucalyptus nitens plantation in Australia being harvested for pulp logs. Trees were felled and bunched with a feller‑buncher in spring, then left infield for four weeks to promote bark adhesion and reduce bark loss. A skidder extracted the trees to roadside where a processor processed them to predominantly 10u2005m logs. Machine productivities were calculated from estimated tree and log volumes and cycle times recorded from video recordings. The feller‑bunchers productivity (65 m3 PMH0−1) was less than expected as it appeared to be underpowered to handle the larger trees on the study site. The skidders productivity (56 m3 PMH0−1) was comparable to those reported in studies under similar conditions and with bark retained. The roadside processors productivity (25 m3 PMH0−1) was lower than expected. This was believed to result from the operator separately stacking 10u2005m and 5u2005m logs, and the lower feed speed resulting from slippage due to the reduced feed roller pressure used in the study to reduce bark loss. Future research could identify feed rollers that increase feed speed while retaining bark. Harvest system costs (AUD18 GMt−1) were similar to those reported for a eucalypt roadside processing trial where bark was removed. These results suggest that retaining bark on the logs at roadside did not affect the harvesting systems productivity or costs.