Machine productivity and residual harvesting residues associated with a cut-to-length harvest system in southern Tasmania

The cut-to-length method is a preferred method for harvest of pine plantations in Australia. The cut-to-length method studied in southern Tasmania consists of a feller-buncher, processor, forwarder, grapple loader and tractortrailers that were producing only pulp logs for the plantation owner Norske Skog. An elemental time study method was applied to evaluate the productivity of the machines within the flat terrain, Pinus radiata plantation. Multiple regression was used in SPSS to develop the productivity prediction models. The productivity of the feller-buncher and processor averaged 122.20 m³ per productive machine hours excluding all delays (PMH₀) and 84.32 m³ PMH₀ ^?1, respectively. The average productivity for the forwarder, grapple loader and truck were 80.90 m³ PMH₀ ^?1, 100.80 m³ PMH₀ ^?1 and 27.40 m³ PMH₀ ^?1, respectively. The average fuel consumption of the feller-buncher, forwarder and processor were also documented. The trial assessed harvest residue left on the site and found 238.7 GMt ha^?1 (31% of total biomass above the stump) was left of which 46% was stemwood. These research findings can be used for harvesting planning and improving logging efficiency.     

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

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 10?m logs. Machine productivities were calculated from estimated tree and log volumes and cycle times recorded from video recordings. The feller?buncher's 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 skidder's productivity (56 m3 PMH₀^?1) was comparable to those reported in studies under similar conditions and with bark retained. The roadside processor's productivity (25 m3 PMH₀^?1) was lower than expected. This was believed to result from the operator separately stacking 10?m and 5?m 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 system's productivity or costs.     

Time Consumption and Production Costs of Two Small-Scale Wood Harvesting Systems in Northern Greece

A field-based study was carried out to determine the productivity and production cost of the tree length (TL) and the wood assortment (WA) systems implemented under small-scale forestry conditions in two Scots pine stands in Northern Greece. Tree felling and processing productivity were estimated at 8.64 m³ per productive machine hour (PMH^?1) and 10.21 m³ PMH^?1, respectively. Wood felling and processing times were strongly dependent on dbh and total tree volume. However, when manual debarking was also considered the productivity rates decreased to 1.96 and 1.43 m³ PMH^?1, respectively. Skidding productivity was calculated to be 3.35 m³ PMH^?1 for TL and 7.17 m³ PMH^?1 for WA, respectively. Strong correlations have been found between the net skidding time and (a) the skidding distance and (b) the load per turn in both wood harvesting systems. Production costs varied greatly, from 19.38 € m^?3 up to 44.81 € m^?3 of roundwood depending on the harvesting system and the inclusion of debarking. The findings suggest that the WA system is more efficient in terms of productivity and production cost than TL, and that there is a substantial optimization potential. The optimization potential can be encoded in four suggestions: (a) opening up of more forest roads to reduce high skidding times, (b) replacement of manual debarking by mechanical debarking at the sawmill, (c) replacement of old pieces of equipment with newer ones and (d) training of the existing workforce.     

Performance,Capability and Costs of Small-Scale Cable Yarding Technology

The authors tested two mini-yarders, one for uphill and the other for downhill extraction. The two machines were modern commercial models, offering state-of-the-art yarding technology on a miniature scale and at a much lower cost than required for purchasing a full-size tower yarder. The two units must not be regarded as alternative, but rather as complementary, since they offer different capabilities and advantages. Both machines were tested while harvesting firewood from the thinning of young beech stands in Central Italy. The tests indicated that both units can reach a productivity between 1.5 and 2.4 m³ SMH⁻¹, including all delays, as well as set-up and dismantle time. Calculated extraction cost ranged between 24 and over 30€ m⁻³. The authors calculated a set of regression equations for estimating machine productivity as a function of the main work conditions. The performance of the studied mini-yarders does not seem much inferior to that achieved by professional light tower yarder under the same work conditions, but the lighter construction of the small-scale units may result in a lower resistance to wear and abuse. In any case, mini-yarders seem ideal for deployment under the typical conditions of small-scale forestry, offering a good solution to wood extraction on steep terrain, competitive with animal and winch logging in terms of productivity, cost and operator comfort.     

Cost-productivity analysis of South African pine sawtimber mechanised cut-to-length harvesting

The South African forestry industry is experiencing an increase in the number of fully mechanised timber-harvesting systems. Understanding the productivity of these systems, for which data is currently limited for South Africa, is an important step to maximise the utilisation of machines being used. A time study of a mechanised cut-to-length system was conducted in Pinus elliottii sawtimber plantations in the Southern Cape forestry region of South Africa. A harvester and a forwarder were studied with the intention of analysing the division of work time amongst work elements, modelling each machine’s productivity and cost, and estimate fuel consumption. For the harvester’s productivity, a multiple regression model was developed using diameter at breast height (DBH), average distance moved per work cycle and slope class as predictors (adjusted R²? = 0.80). The harvester had a mean productivity of 33.6 m³ per productive machine hour (PMH₀) under the current conditions with most of the productive time being used in the moving element. It consumed 25.5 L PMH₀ ^?1 of diesel on average. The forwarder’s fuel consumption was calculated as 16.8 L PMH₀ ^?1, while productivity was 46.8 m³ PMH₀ ^?1. The forwarder spent the longest portion of the work cycle in the loading and unloading phases. A productivity regression model was created that included load size and distance moved during the driving in the loaded phase (adjusted R?² = 0.78).     

Feasibility of a harvesting system for logging residues as unutilized forest biomass

The concept of a “harvesting system for unutilized forest biomass by a processor and a forwarder” is examined for the purpose of constructing a system to harvest logging residues (or slashes) as a new resource for energy. The rate of slash harvesting, α, and the energy input rate of hauling slashes,p (%), are defined as indices of the possibility of harvesting slashes and the utilization of slashes for energy, respectively. From an analysis of the field experiment, both the volume of logs hauled by the forwarder per day,E _F (m³/day), andp are expressed as functions of the hauling distance,L(m). The productivity of the processor,E _P (m³/day), andL were used to calculate α. Results showed that α was approximately 0.95 for the experiment site, indicating that almost all the slashes could be hauled. It was recognized that the energy utilization of slashes was feasible for this site becausep was less than 1 %. The hauling cost per unit weight of slashes was calculated as 15.4 yen/kg on an oven-dry weight basis. This high cost clarified that the cost must be reduced by taking measures such as enhancing the hauling efficiency of the forwarder. A part of this paper was orally presented at the 5th Annual Meeting of the Japan Forest Engineering Society (1998).     

An evaluation of the economics and productivity of fully mechanised tree seedling planting in Brazil

From an economic point of view, Eucalyptus is the most important forest genus in Brazil, covering more than 5 million ha. However, most of the silvicultural practices have a low level of mechanisation compared with harvesting and logging operations. This study presents an evaluation of the economics and productivity of the first Brazilian experience of using a planter device attached to an excavator boom while performing eucalypt seedling planting. A classic time-and-motion study was performed on two commercial tree spacings to evaluate the economic efficiency. Considering the final cost of planted seedlings, the wider spacing was 17% higher than narrower spacing, due to a higher productivity: 355 and 324 seedlings per productive machine hour (pmh), respectively. Total cost was 66.84 € pmh^?1 and 0.21 € planted seedling^?1 with wider spacing.     

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$ 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.     

Productivity and cost analysis of semi-mechanised and mechanised systems on the Viphya forest plantations in Malawi

At least 200 000 m³ of timber is harvested annually using semi-mechanised harvesting systems on the Viphya forest plantations in Malawi. Although these systems have long been used on the Viphya, no investigation on their productivity has so far been reported. Additionally, the absence of localised productivity analyses in Malawi has created a paucity of information on appropriate timber harvesting systems for production maximisation and cost minimisation. The objective of this study was to compare the production rates and operational costs of chainsaw/grapple skidder (semi-mechanised) and feller-buncher/grapple skidder (mechanised) harvesting systems in order to determine the economic feasibility of mechanised systems in the Viphya forest plantations. The study was conducted in Pinus kesiya compartments at the Kalungulu and Champhoyo forest stations of the Viphya forest plantations. A work study approach was followed to capture harvesting time and volume data for the semi-mechanised system. Secondary work study data were used to simulate productivity of the mechanised system on similar compartment conditions. A timber-harvesting costing model was used to analyse the results. The study showed that the simulated mechanised system was associated with lower operating costs and inventories with higher production rates than the semi-mechanised system. The cost marginal difference was US$0.89 m^–3. It was therefore established that migration to mechanised systems could optimise timber harvesting productivity on the Viphya in future, if optimal volumes are available to ensure the efficient application of the mechanised harvesting system.     

A study on the productivity and cost of cable logging in Turkey

Tower yarders have recently been introduced to forestry in Turkey. Clarification of the productivity and cost of logging using the tower yarder is often requested because the cost for machinery is a significant factor in all calculations concerning mechanized operations. Machines are often extremely expensive compared with the low cost of labor in developing regions. In this study, a new logging system using a tower yarder was compared with a conventional system using a stationary yarder in terms of productivity and cost. The research was conducted in the northeast of Turkey, in 1989 and 1992. The productivity of the tower yarder and the stationary yarder was found to be 5.655 m³/h and 5.002 m³/h, respectively. Harvesting cost was analyzed based on observed productivity. The harvesting costs of the tower yarder and the stationary yarder were found to be 47,410 TL/m³ and 17,553 TL/m³, respectively. With the tower yarder, the machine cost reached 93.1 % of the harvesting cost while the machine cost using the stationary yarder reached 71.1%. A part of this paper was orally presented at the 3rd Annual Meeting of the Japan Forest Engineering Society (1996).     

Application of a Small-Scale Equipment System for Biomass Harvesting

The small-scale harvesting equipment system has been and continues to grow in use in forestry operations in some regions in the world. This harvest system can include a range of equipment types, such as feller-bunchers or chainsaws, skidders or farm tractors, and chippers. These machines are generally smaller, lower cost and less productive than larger, more advanced forestry machines. The objective of this project was to investigate the feasibility of a small scale harvesting system that would produce feedstock for a biomass power plant. The system had to be cost competitive. A boom-type feller-buncher, a small grapple skidder and a chipper were tested as a small-scale system. In this study, feller-buncher and skidder productivity was determined to be 10.5 m³ per productive machine hour, and production for the chipper was determined to be 18 m³ per productive machine hour. Production from the system did not reach the desired levels of 4 loads/day (25 m³/load); however, the system was able to produce about 3 loads/day. The results showed that the system currently could fill a roadside van for $16.90/m³, but suggested machine modifications could potentially reduce the system cost to $12.73/m³. Residual stand damage was minimal, especially on flatter ground and not operating on a slash layer. Soil disturbance from the harvesting system was predominantly undisturbed or classified as a shallow disturbance.     

Determining the effect of tree size,bark-wood bond strength and tree form on the productivity of an excavator-based harvester in Acacia mearnsii in the KwaZulu-Natal forestry region of South Africa

The aim of this study was to determine the effect of tree size, bark-wood bond strength and tree form on the productivity of cut-to-length harvesting of Acacia mearnsii, using an excavator-based harvester with a SP Maskiner harvester head in the KwaZulu-Natal forestry region of South Africa. Tree diameter and height measurements were used to determine individual tree volumes, after which the trees were classified into different bark-wood bond strength and tree-form classes. Time studies were carried out to determine harvester productivity. The results showed that tree size plays a crucial role in the productivity of the harvester, but bark-wood bond strength and tree form also influence productivity. The harvester productivity varied from 5.5 m³ per productive machine hour (PMH) in 0.05 m³ trees to 16.9 m³ PMH^?1 in 0.25 m³ trees The bark-wood bond strength did not influence harvester productivity when handling small trees of less than 0.1 m³. In small trees, the productivity of the harvester was also not affected by different form classes, but as tree size increased, there was greater productivity variation between the different form classes.     

The effect of quality bucking and automatic bucking on harvesting productivity and product recovery in a pine-dominated stand

On-board computers (OBC) of harvesting machines can now provide optimized bucking (task of cutting stems into different log lengths) by relying on value and demand matrices. Despite existing benefits of these systems in certain countries, they remain largely underutilized and generally poorly understood in German mechanized forest operations. The study aimed to compare and quantify the differences in harvesting productivity and value recovery between two treatments: quality bucking (OFF) and automatic bucking (ON). A mature forest stand with a high proportion of Scots pine (Pinus sylvestris L.) was divided into plots (30 m × 100 m) where initial tests of both treatments were randomly distributed and replicated 10 times for a total of 11 plots per treatment. Pre-harvest inventory was performed on each tree targeted for removal via a commercial thinning silvicultural treatment. Mechanized harvesting was performed with an excavator-based Atlas Kern T23 Königstiger single-grip harvester. The same assortment specifications and prices were used for both treatments but on-board optimized bucking solutions were applied in the ON plots, whereas the operator had full control of the products to be recovered in the OFF plots. During harvesting operations, continuous time and motion was performed in all plots. Average harvesting productivity was higher—but not statistically significant—in OFF plots compared to ON plots by 2.0 and 0.46 m³/PMH₀ for pine and spruce trees, respectively. Even if there was no difference detected in volume recovery for both treatments and tree species, value recovery was more than 1.60 € per cubic meter higher for pine in larger diameter classes when using quality bucking. This may be due to the fact that the algorithm of the OBC is designed for pine trees with a simpler crown architecture than trees harvested in this study. Results supporting quality bucking over automatic bucking in a Scots pine-dominated stands provide important forest operational information to managers.

     

Preliminary trials of the BioBaler working in Brazilian eucalypt plantations

The increasing demand for renewable energy feedstock has raised interest in growing eucalypts for fuel wood production, which is achieved by establishing very dense plantations cut every 18–24 months. The high moisture content of fresh Eucalyptus may handicap cut-and-chip operations, and offers a unique opportunity for supply chains based on baling. Therefore, the Canadian-made BioBaler was tested in Brazil on a eucalypt energy plantation, as well as on the resprouts generated by a conventional pulpwood plantation after severe frost damage. The BioBaler coped well with both crops, achieving high productivity levels: 7.1 and 3.3 t h^?1 in the energy plantation and the failed crop treatments, respectively. Harvesting cost was estimated at €13 t^?1 and €26 t^?1 for the energy plantation and the failed crop, respectively. Productivity and harvesting cost were comparable with those reported in previous studies conducted in other countries on similar crops. Productivity was directly proportional to field stocking. Future studies should test the machine on a wider range of work conditions and include bale extraction, storage, processing and transportation, in order to estimate an overall supply chain cost and allow direct comparison with alternative options.     

A productivity model for first thinning of Pinus patula using a tractor and double-drum winch in South Africa

The productivity of skidding tractors in intermediate harvesting operations has not been determined in Mpumalanga, South Africa. The objective of this study was to develop a productivity model using a farm tractor in first thinning operations in Pinus patula compartments. A work study design was used to assess the performance of a skidding agricultural tractor. From 350 samples, important data variables collected were elemental times for each work cycle, extraction distance, slope and load volume. Stepwise and subsets regression analyses were conducted prior to multiple linear regression analysis. Analysis of variance was used to compare mean productivity estimates of the different models developed. Results showed that the best model was estimated by an interaction of distance × slope (ds), distance × load volume (dv) and slope × load volume (sv) as follows: ln(?₂) = 1.33–0.00154ds + 0.00174dv + 0.161sv. The mean estimate for this model was 5.036 m³ m h^?1. The developed models predicted similar results to estimation results of the observed model, although there were statistically significant (P < 0.001) differences among mean estimates (3.6–5.5 m³ m h^?1). All of the three models yielded R²_adj. = 38%; SE = 0.458% at P < 0.001. It can be speculated that the remaining variation not explained by the models may be associated with long extraction distances, delays and the effect of slope as a main variable in the model. While the developed models mirrored reasonably well with the observed estimates of skidding productivity, these models should not be stretched to conditions dissimilar to those of their generation. Future research focus should be made on (1) effects of weather conditions and vehicular characteristics on skidding productivity and (2) the effect of winching lines on skidding productivity.     

Harvesting alternatives for mallee agroforestry plantations in Western Australia

The authors tested two harvesting systems especially designed for mallee agroforestry plantations on farmland. Both systems were based on versatile forest technology commonly used for conventional logging operations. They differed especially for the felling technology: small-scale drive-to-tree or industrial swing-to-tree equipment. Both systems were tested side-to-side on 12 experimental plots each. The resulting harvesting cost was 22 and 27 AU$ t^?1, for the industrial and the small scale system, respectively. Chipping represented between 60 and 80 % of the overall harvesting cost, and offered much room for improvement. The industrial system always offered the lowest harvesting cost, regardless of annual usage, when equipment mobilisation costs were not considered. The productivity of conventional forestry equipment was strongly dependent on belt stocking and tree size. If the diameter at ankle height dropped below 10 cm, economic viability decreased very rapidly.     

An Economic Evaluation of a Small-Scale Timber Harvesting Operation in Western Maryland, USA

As forests of the eastern United States become fragmented into smaller ownership parcels, there is a growing need for timber harvesting contactors who can economically harvest timber and perform silvicultural operations on small tracts. Traditional large-scale harvesting operators are ill-suited for work on small parcels, due to their high fixed costs. By contrast, small-scale operators, characterized by few workers and low capital investment, offer an opportunity to serve this landowner segment. This paper presents financial and productivity results from a small-scale timber harvesting pilot study conducted on small forested parcels in western Maryland, USA. Acceptable financial performance is possible for these operations, provided that the operator pays close attention to the important factors determining productivity and profitability, including: (1) average tree volume, (2) net delivered price, (3) time utilization, and (4) distance to the site. Although profitable harvesting of saw log quality trees on parcels less than 10 ha is possible, harvesting of small or poor-quality trees remains economically unattractive.     

Biomass harvesting in Eucalyptus plantations in Western Australia

Australia is at an early stage of exploring the use of forest biomass to generate energy. This study evaluated the biomass yield and the productivity rates of equipment for harvesting biomass in a poor-quality eucalypt plantation. The operation consisted of a tracked feller-buncher, grapple skidder and mobile chipper. Time study methods were used to measure the harvesting operation. A multiple regression model was constructed to predict skidding productivity. Biomass production was 63.9 t ha^?1 based on the recorded load weight of eight trucks. Delays were documented and analysed. The average delay for all equipment was about 30% of working time. The study results will help guide biomass harvesting managers to estimate productivity and cost of similar operation sites.     

Work environment of processor operators

Seven processor operations were investigated to examine the work environment of the processor operator. The invisible objects in the visual field of four processors were the jib, head, instrument for measuring logs, wiper, and cabin. The operator looked mostly at “the head of the processor” during delimbing, bucking and arranging; “the delimbed tree-length log for bucking” during delimbing and bucking; “the bucked log” during bucking and arranging; and “the sides of the road” during moving and skidding. From the frequency of fixation for each fixated object, the instrument for measuring logs and the head was found to require the most attention. The height of three processors’ steps for “mounting and alighting” were higher than the optimum value (58 cm), obtained from an anthropometric investigation of forest machine operators. The levers and pedals of four processors were arranged at suitable positions, according to JIS guidelines.     

A Case Study on the Productivity of Forwarder Extraction in Small-Scale Southern Italian Forests

Most timber harvesting operations in the southern Mediterranean area of Italy can be considered to be in an early stage of mechanization. It is mainly based on agricultural tractors that are sometimes equipped with specific forest-related accessories such as winches, hydraulic cranes, or log grapples. In recent years, there has been an increase of specialized forestry machines working in Calabria, southern Italy, including forwarders, skidders and cable yarders. This study assesses the efficiency and costs of extraction using forwarders, as a mechanized alternative to agricultural tractors and horse logging. Time studies were conducted to quantify the productivity and operational cost of log forwarding for two John Deere forwarders in two different coniferous stands: (A) Calabrian pine and (B) silver fir. The empirical time study included 100 forwarding cycles (i.e., 50 for each site) that were broken down into four different work phase elements. Models for cycle time, total productivity and individual work phases were calculated. The average load per cycle was 11.8 m³ in stand A and 9.97 m³ in stand B and the average one-way forwarding distance was 306 m in A and 597 m in B. The average productivity per scheduled machine hour (SMH) was 14.4 m³ in A and 15.7 m³ in B, while the costs, calculated to be 3.60 €/m³ in A and 4.90 €/m³ in B, were considered lower respect traditional methods.