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Recent developments in on-board technology have enabled automatic collection of follow-up data on forwarder work. The objective of this study was to exploit this possibility to obtain highly representative information on time consumption of specific work elements (including overlapping crane work and driving), with one load as unit of observation, for large forwarders in final felling operations. The data used were collected by the John Deere TimberLink system as nine operators forwarded 8868 loads, in total, at sites in mid-Sweden. Load-sizes were not available. For the average and median extraction distances (219 and 174 m, respectively), , , , and effective work (PM) accounted for ca. 45, 19, 8.5, 7.5 and 14% of total forwarding time consumption, respectively. The average and median total time consumptions were 45.8 and 42.1 minutes/load, respectively. The developed models explained large proportions of the variation of time consumption for the work elements and , but minor proportions for the work elements and Based on the means, the crane was used during 74.8% of PM time, the driving speed was nonzero during 31.9% of the PM time, and occurred during 6.7% of the PM time. Time consumption per load was more strongly associated with distance than with extraction distance, indicating that the relevance of extraction distance as a main indicator of forwarding productivity should be re-considered.LoadingUnloadingDriving emptyDriving loadedOther time Driving emptyDriving loadedLoading Unloading. LoadingLoadingSimultaneous crane work and drivingLoadingLoading drive

On Nordic clearcuts, todayâs tree planting machines produce high-quality but costly regenerations. Much of this high cost is attributable to the planting machinesâ low productivity. One promising way of raising productivity is to lessen the time spent manually reloading seedlings onto the carousels of crane-mounted planting devices. Using MagMat, a carousel test-rig designed by engineering students, we studied how much faster tray-wise seedling reloading is on the Bracke Planter compared to reloading with todayâs seedling-wise-loaded carousel. The MagMat test-rig held eight Hiko cultivation trays from which seedlings were deplugged individually and dropped into the planting tube. The time study confirmed that seedling reloading was on average twice as fast with MagMat compared to todayâs seedling carousel, thereby increasing assumed planting machine productivity by 8â9% depending on the planting device used. MagMatâs cost-efficiency was analysed to be particularly reliant on its added investment cost, mechanical availability and how quickly trays can be switched automatically. Nevertheless, MagMatâs field performance illustrated the overall potential of tray-wise loading compared to piecewise seedling loading for increasing the productivity of crane-mounted planting devices. Also, deplugging proved to be a reliable method of extracting seedlings from the rigid, copper-painted Hiko cultivation trays even when performed at the excavatorâs boom-tip during mounding work. We conclude that, rather than piecewise seedling loading, tray-wise loading combined with deplugging seedlings from suitable cultivation trays is a reliable and much more time-efficient method to feed seedlings on probably any type of tree planting machine.

Forwarding has been carried out for 50 years, but much is still unknown about this work. Its complexity comes from both stand features and essential decision-making. Forwarding time consumption is influenced by e.g. log concentrations and number of assortments. Traditionally, focus has been on the total log concentration (TLC), referring to all logs at the harvesting site. However, we focused on forwarded log concentration (FLC), the load-specific log concentration which depends on the assortment distribution at harvesting site and the load-specific number of assortments. To evaluate the effects of TLC, number of assortments in a load and FLC on the loading and unloading times, a standardized field experiment was carried out. Pile and load sizes were constant, while TLC and FLC were manipulated by varying the pile distribution on the test path. For all work elements, the time consumption per m was significantly affected by the number of assortments that were loaded, but only the âdriving while loadingâ work element was also significantly influenced by TLC. However, when untangling the intercorrelation between tested factors, it was found that the time consumption for driving while loading significantly decreased as a function of FLC and was unaffected by the number of assortments in a load. That FLC influences the forwarding time consumption highlights the need to study the effects of combining various assortment proportions in a load. Such knowledge will enable analysis of the most efficient number and assortment proportions to combine in the various loads required to forward a given stand.3

Todayâs crane-mounted planting heads plant seedlings with biologically similar or better results than operational manual planting. However, the total cost of mechanized tree planting in southern Sweden must decrease at least 25% to compete economically with manual planting. Although seedlings packed in machine-specific packaging increase the productivity of planting machines by reducing seedling reloading time, they also increase logistics and investment costs. In this study, we analyzed the total cost of outplanting seedlings with an excavator-mounted Bracke Planter and seedlings packed according to four different concepts: cultivation trays, cardboard boxes, band-mounted seedlings in cardboard boxes and linked pots in container modules. The total cost per planted seedling was calculated for each packaging system as the sum of all costs from nursery to the recovery of empty packaging. The results showed that todayâs system of transporting seedlings in cultivation trays is the most cost-efficient of the four alternatives. Machine-specific seedling packaging was 16â23% costlier per planted seedling than cultivation trays when trucking distances were 100 km. Sensitivity analyses indicated that machine-specific seedling packaging increased in cost-efficiency relative to cultivation trays primarily when more planting machines were contracted, but also as planting machine fixed costs and productivity increased. Moreover, the relative cost-efficiency of band-mounted seedlings, but not seedlings in container modules, increased with increasing trucking distance. Thus, we show that investments in machine-specific seedling packaging for todayâs planting machines are justified only when the fixed costs, productivity and number of contracted planting machines increase substantially.

Stumpwood attracts renewed interest due to increased use of forest biomass for bioenergy. In Nordic countries stumps are generally uprooted with crawler excavators, which have strong cranes (ca. 400 kNm gross lift torque), but are not designed for moving in forest terrain. Their use is based on practical experience with available and tested machine types rather than thorough examinations of requirements, partly due to limited knowledge of force requirements for uprooting of stumps. Therefore, in this work mean and maximum forces required to vertically uproot stumps of Norway spruce (Picea abies) and birch (Betula spp.) were quantified together with the effects of various soil types and uprooting methods. The used excavatorâs crane-mounted uprooting device enabled comparisons between usage of solely crane force, and a method in which preparatory loosening forces were applied prior to crane force. Uprooting stumps in single pieces proved difficult; 61% split unintentionally. Force requirements were similar across tree species, increasing curve-linearly with stump diameter, and stumps uprooted in a single piece required more force than split stumps. Preparatory loosening reduced crane force requirements and, surprisingly, less force was required to uproot stumps from a mesic, till soil than from a moist, finer-textured soil. No stump required more than 60 kN crane force and functions for maximum force requirements indicate that powerful harvesters and forwarders (gross crane lifting capacity of 273 and 155 kNm, respectively) should be able to uproot all stumps with ⤠61 cm and ⤠32 cm diameter, respectively, in one piece. Larger stumps could be managed if it is acceptable that stumps are split before uprooting.

When recovering logging residues (LR) for bioenergy its density should be increased before road transport, otherwise a low proportion of the trucksâ load capacity will be used. One way this can be currently done is to compress LR into bundles that are forwarded to roadside landing. A less well-developed alternative is to forward loose LR and bundle it at landing. In the presented study, a prototype specifically developed for road-side bundling was found to produce larger, heavier bundles than bundling machinery intended for in-field use (mean length, diameter and raw bulk density 4.7 m, 0.8 m and 285 kg m, respectively, with 299â445 kg oven dry matter per bundle). The machine was also at least 30% more productive than previously described in-field bundling systems, producing 14â19 bundles per productive work hour (PWh), equivalent to 5.2â7.8 oven-dry tonnes PWh. Bundles were estimated to use 67â86% of an LR truckâs 30 tonnes load capacity, similar to proportions used when transporting loose LR. However, a continuous feeding and compressing process would probably almost double productivity, while longer bundles would enable full use of truck load capacity. With such improvements bundling at road-side could provide a viable alternative to current LR-recovering systems.â3â1

Firewood, which is mainly processed by the consumer, is still an important source of energy for heating houses in industrialised countries. Possibilities to compare the mechanizationâs impact on efficiency of firewood processing are limited, due to variations between working conditions in previous studies. Therefore, the objective was to compare time consumption for two small-scale firewood processing systems with different levels of mechanisation under identical conditions. The systems were tested on two classes of wood: one with a homogeneous and medium-sized diameter of logs and one with a mixture of small and large-diameter-logs. Differences in time consumption were analysed for correlations with physical workloads, deviations to routine operations, operator influences and operator perceptions. Twelve operators (60â79 years old) were studied and they showed large variation in time consumption. However, the within-operator time consumption patterns were consistent. In other words, operators all responded similarly to the different combinations of systems and wood classes, but at different absolute levels. The time required to process a unit volume of wood was 25â33% lower when the more highly mechanised system was used, and the time required was 13â22% lower for the homogeneous wood class. Physical work load, deviations and perceptions of the work varied between operators, but were weakly correlated with time consumption. The resultsâ implications for analyses of investments in equipment for firewood-processing for self-sufficiency purposes are discussed.

Stem size has the greatest effect on harvester productivity, and stem sizes vary in a forest stand. How these within-stand variations influence harvester productivity is normally not considered in studies or predictions of productivity. This study suggests reasons as to why the current production and/or application of productivity models are prone to bias from stem size variations in a stand, irrespective of whether models were developed from tree-based or stand-based studies. Moreover, it also provides empirical data on the stand stem size variation's influence on stand-based modeling of harvester productivity. Data from 11 harvesters in 347 final fellings and four harvesters in 80 thinnings were used. The mean productivity was 26.7 and 11.0 m3/PMh5 in final felling and thinning, respectively, and the mean stem size explained most of the observed variation. The productivity in final felling decreased with increased levels of stand stem size variation, as well as with increases in the proportion of broadleaf trees in the stand. For thinnings, productivity increased with increases in the proportion of pine trees in the stand, but there was no significant effect of stand stem size variation or other tested factors. The results show that stand stem size variation is a relevant factor to consider when modeling and predicting harvester productivity. [ABSTRACT FROM AUTHOR]

As various methods for precision inventories, including light detection and ranging (LiDAR), are becoming increasingly common in forestry, planning at the individual-tree level is becoming more viable. In this study, we present a method for finding the optimal thinning times for individual trees from an economic perspective. The method utilizes a forest growth model based on individual trees that has been fitted to Norway spruce (Picea abies (L.) Karst.) stands in northern Sweden. We find that the optimal management strategy is to thin from above (i.e., harvesting trees that are larger than average). We compare our optimal strategy with a conventional management strategy and find that the optimal strategy results in approximately 20% higher land expectation value. Furthermore, we find that for the optimal strategy, increasing the discount rate will reduce the final harvest age and increase the basal area reduction. Decreasing the cost to initiate a thinning (e.g., machinery-related transportation costs) increases the number of thinnings and delays the first thinning. Key words: forest management, optimization, precision forestry, simulation, thinning. La planification a l'echelle de l'arbre devient de plus en plus viable a mesure qu'augmente le recours a diverses methodes d'inventaire de precision en foresterie, telles que le lidar (<>). Dans cette etude, nous presentons une methode visant a determiner les periodes optimales d'application d'une eclaircie pour les arbres individuels d'un point de vue economique. La methode utilise un modele de croissance forestiere a l'echelle de l'arbre qui a ete ajuste a des peuplements d'epicea commun (Picea abies (L.) Karst.) du nord de la Suede. Nous avons trouve que la strategie d'amenagement optimale consiste a eclaircir par le haut, c'est-a-dire a recolter des arbres plus gros que la moyenne. Nous avons compare notre strategie optimale a une strategie d'amenagement conventionnelle et avons constate qu'elle produit une augmentation de la valeur actualisee des terres d'environ 20 %. De plus, lorsque la strategie optimale est associee a une augmentation du taux d'actualisation, l'age de la recolte finale diminue et le prelevement en surface terriere augmente. Une diminution des couts associes a l'eclaircie (p. ex., les couts de transport mecanise) augmente le nombre d'eclaircies et retarde l'application de la premiere eclaircie. Mots-cles: amenagement forestier, optimisation, foresterie de precision, simulation, eclaircie., Introduction Given the ecological and economic importance of forests, it is not surprising that much effort has been invested in developing and improving forestry practices. Increasingly common use of remote [...]

Ground-based mechanized forestry requires the traversal of terrain by heavy machines. The routes that they take are often called 'machine trails' and are created by removing trees from the trail and placing the logs outside it. Designing an optimal machine trail network is a complex locational problem that requires understanding how forestry machines can operate on the terrain, as well as the trade-offs between various economic and ecological aspects. Machine trail designs are currently created manually based on intuitive decisions about the importance, correlations, and effects of many potentially conflicting aspects. Badly designed machine trail networks could result in costly operations and adverse environmental impacts. Therefore, this study was conducted to develop a holistic optimization framework for machine trail network design. Key economic and ecological objectives involved in designing machine trail networks for mechanized cut-to-length operations are presented, along with strategies for simultaneously addressing multiple objectives while accounting for the physical capabilities of forestry machines, the impact of slope, and the operating costs. Ways of quantitatively formulating and combining these different aspects are demonstrated, together with examples showing how the optimal network design changes in response to various inputs. Key words: mathematical modeling, forest engineering, machine trail network, environmental impact, logistics. L'exploitation forestiere mecanisee necessite que la machinerie lourde se deplace sur le terrain. Les chemins qu'elle emprunte sont souvent appeles des sentiers de machines et sont crees en enlevant les arbres et en placant les billes sur le cote du sentier. La conception d'un reseau optimal de sentiers de machines est un probleme complexe de localisation qui exige de comprendre de quelle facon la machinerie forestiere peut operer sur le terrain, ainsi que les compromis entre divers aspects economiques et ecologiques. La conception des sentiers de machines est actuellement realisee manuellement sur la base de decisions intuitives au sujet de l'importance, de la correlation et des effets de plusieurs aspects potentiellement antagonistes. Les sentiers de machines mal concus pourraient engendrer des operations couteuses et avoir des impacts nefastes sur l'environnement. Par consequent, cette etude a ete realisee dans le but de developper un cadre d'optimisation holistique pour la conception des reseaux de sentiers de machines. Les objectifs ecologiques et economiques cles retenus dans la conception de reseaux de sentiers de machines pour des operations mecanisees de recolte par bois tronconnes sont presentes, ainsi que les strategies pour repondre simultanement a plusieurs objectifs tout en tenant compte des capacites physiques de la machinerie forestiere, de l'impact de la pente et des couts d'operation. Des facons de combiner et de formuler quantitativement ces differents aspects sont illustrees avec des exemples montrant comment la conception du reseau optimal change en reaction a differents intrants. [Traduit par la Redaction] Mots-cles : modelisation mathematique, genie forestier, reseau de sentiers de machines, impact environnemental, logistique., 1. Introduction In ground-based forestry, large volumes of timber are extracted from forest to roadside using heavy vehicles. When conducting 'close-to-nature' forestry, the machines should ideally be able to operate [...]

There are many factors to consider when deciding which technologies to use in forest operations and how to plan their use. One important factor is the overall cost when choosing between the established two-machine system (TMS) with a harvester and a forwarder, and a one-machine system with a harwarder in final fellings. Such considerations can be done with different model approaches, all of which have their strengths and weaknesses. The aim of this study was to analyze and compare the TMS and harwarder potential using a Detailed Optimization (DO) approach and an Aggregated Heuristic (AH) approach. The main differences are the aggregation of seasons, including machine system teams, and spatial considerations. The analyses were done for one full year of final fellings for a large forest company's region in central Sweden, containing information necessary for calculating costs for logging, relocation between stands and traveling between the operator's home bases and the stands. The approaches were tested for two scenarios; when only TMS were available, and when both TMS and harwarders were available. The main results were that the approaches coincided well in both potential to decrease total costs when harwarders where available, and distribution of TMS and harwarders. There were some differences in the results, which can be explained by differences in thecalculation approach. It was concluded that the DO approach is more suitable when detailed analyses are prioritized, and the AH approach is more suitable when a more approximate analysis will suffice or the available resources for making the analysis are more limited. [ABSTRACT FROM AUTHOR]

In many parts of the world, contractors account for the main share of harvesting work. Harvesting is characterized by innate complexity and volatility, and this can affect contractors' workflow and ultimately their profitability. Thus, there is certainly a need for flexibility in harvesting service provision and procedures, but our current knowledge about contractors' workflow variations are limited. This study investigates workflow variations in harvesting services by comparing monthly variations between contractors' workload in terms of harvested volumes and the time spent on operations. The data originates from 77 machines belonging to contractors and their harvesting of 6.6 million m3 of roundwood in Sweden during a two-year period. The results indicate differences between contractors' workflow variations which can be attributed to the number of machines, machine sizes, and the workload in harvested volume and hours. These findings are relevant for guiding both the customer and contractor in this business relationship, and they could also serve as a basis for further research on the need for flexibility to effectively increase and decrease volume production in harvesting services. [ABSTRACT FROM AUTHOR]

In conventional mechanized cut-to-length systems, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs directly into the load spaces of transporting machines as they are cut. Such integrated loading could result in cost reductions, shorter lead times from stump to landing, and lower fuel consumption. However, it might also create waiting times for the machines involved, whereas multifunctional machines are likely to be expensive. Thus, it is important to analyze whether or not the advantages of any changes outweigh the disadvantages. The conventional system was compared with four potential systems, including two with autonomous forwarders, using discrete-event simulation with stochastic elements in which harvests of more than 1000 final felling stands (containing in total 1.6 million [m.sup.3]) were simulated 35 times per system. The results indicate that harwarders have substantial potential (less expensive on ≥80% of the volume and fuel consumption decreased by ≥18%) and may become competitive if key innovations are developed. Systems with cooperating machines have considerably less potential, limited to very specific stand conditions. The results conform with expected difficulties in integrating processing and transporting machines' work in variable environments. Resume: Dans les procedes mecanises conventionnels de recolte par bois tronconne, une abatteuse-faconneuse coupe et tronconne les arbres en billes qui sont entreposees au sol jusqu'a ce qu'un porteur les ramasse et les transporte jusqu'a une jetee. Une amelioration qui a ete proposee consiste a placer les billes directement dans l'espace de chargement des porteurs a mesure qu'elles sont coupees. Un tel chargement integre pourrait reduire les couts, le delai entre la souche et la jetee ainsi que la consommation de carburant. Cependant, cela peut egalement engendrer des periodes d'attente pour la machinerie concernee alors que les machines multifonctionnelles risquent d'etre onereuses. Par consequent, il est important de determiner si les avantages des changements l'emportent sur les desavantages ou non. Le procede conventionnel a ete compare a quatre procedes potentiels, incluant deux procedes avec porteurs autonomes, en utilisant la simulation d'evenements discrets avec des elements stochastiques au moyen de laquelle la coupe definitive de plus de 1 000 peuplements (contenant au total 1,6 million de [m.sup.3]) a ete simulee 35 fois avec chaque procede. Les resultats indiquent que les machines multifonctionnelles ont beaucoup de potentiel (plus economiques pour [greater than or equal to]80 % du volume et consommation de carburant reduite de ≥18 %) et peuvent devenir competitives si des innovations cles sont developpees. Les procedes qui impliquent la cooperation de differentes machines ont beaucoup moins de potentiel et sont limites a des conditions de peuplement tres specifiques. Les resultats correspondent aux difficultes anticipees par l'integration des machines qui effectuent la transformation et le transport dans des environnements variables. [Traduit par la Redaction], Introduction During the last 50 years, forest operations have been subject to many steps of mechanization. The forces driving mechanization have included labor shortages, an aspiration to perform forestry operations [...]