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The consensus on the factors affecting harvester productivity is generally widely acknowledged in the discipline. However, research results regarding the effect of forking on productivity are diverse. Some studies show that harvester productivity is halved when harvesting double stems compared to single-stem trees, while other studies indicate that forking does not necessarily decrease harvester productivity. These differences in study results can depend on what is considered forking. In our study, the forking occurred above the breast-height level. We defined codominant stems as forked trees too large to be multi-tree handled. In contrast, we defined double crowns as forked trees that could be multi-tree handled. The objective of our study was to analyse how the presence of codominant stems and/or double crowns affects harvester time consumption. The study was conducted in Sweden in 2022, involving two operators and two large harvesters. The 45-year-old Pinus contorta Douglas ex Loudon-dominated stand was clearcut during the study. We found that the presence of codominant stems doubles harvester time consumption per tree, while double crowns had only a minor impact on harvester time consumption. Additionally, total time consumption increased linearly with increasing diameter at breast height. Based on these findings, we recommend that forked trees be removed already during thinning when they can still be time-efficiently multi-tree handled. Dealing with forked trees later during the rotation cycle, when they are too large for multi-tree handling, is excessively time-consuming.

The productivity of cut-to-length machine operators exhibits a significant disparity, with the most productive individuals demonstrating twice the efficiency of their less productive counterparts. This discrepancy is largely attributed to variations in work methods. While supervised training has proven effective in streamlining work methods and enhancing productivity, the availability of forest-machine instructors for supervision is limited. Intelligent coaching systems (ICS) are periodically proposed to address this constraint. ICS are computer-based aids that offer machine operators real-time feedback on their work and guide them on how to rationalize their work. The successful implementation of ICS initially requires the development of systems for automatic work-element detection (AWED). Therefore, this article explores the history, current status, and technological possibilities of AWED. Additionally, key features of ICS are briefly reviewed. Lastly, a broader, interdisciplinary discussion is initiated on how to strategically allocate limited research resources. Questions surrounding the feasible ambition level for ICS and AWED are raised, prompting considerations for the next steps in research and development.

According to the literature, forwarding productivity depends chiefly on log concentration, the number of assortments, mean log volume, load-size, slope, and extraction distance. However, there is not much scientific knowledge available on forwarding in continuous cover forestry (CCF) in boreal forests, nor whether the presence of remaining trees actually affects forwarding productivity. Thus, the objective of our study was to isolate the effect of remaining trees (i.e. stand density) on forwarding productivity during CCF, specifically selection cutting. The results showed that productivity was explained mainly by the log concentration, while other factors had at most minor effects. Most importantly, stand density did not significantly affect forwarding productivity, ceteris paribus. Thus, we conclude that remaining trees do not affect forwarding productivity in boreal forests. Although the study results from this CCF operation must only be cautiously applied to even-aged forestry, our results raise a general question: do we need separate productivity models for thinning and clearcut operations in boreal forests if remaining trees (stand density) do not affect forwarding productivity? Because of the small dataset, we consider our paper to be a pilot study whose findings need to be verified by studies based on larger datasets including several operators and stands.

While even-aged forestry is the dominating forest management system in Sweden, there is an increasing interest in Continuous Cover Forestry. Consequently, the conversion of even-aged stands into uneven-aged ones using e.g. selection cutting can be expected to become more common in Sweden. However, there are no up-to-date studies available on harvester productivity during selection cutting under Nordic conditions. Studying harvest intensity during selection cutting is of interest because lighter harvest intensities lead to higher volume growth and better-preserved forest ambience than heavier intensities. The objective of this study was to examine the effect of harvest intensity on harvester productivity during selection cutting. The field study entailed harvesting either 14%, 28% or 48% of a mature stand's basal area. Harvester productivity was mainly explained by piece size (stem volume), while other factors, including harvest intensity, had only minor effects. This reality means that during selection cutting (thinning from above), piece size increases with decreasing harvest intensity, which in turn increases harvester productivity. Moreover, we observed a mild tendency that operators could select the stems' felling directions and order more freely when fewer trees are harvested. This amelioration increases productivity additionally during lighter harvesting intensities.

Today, conflicts often occur in northern Fennoscandia (also known as Sápmi) between forestry and reindeer husbandry. Continuous cover forestry (CCF) is requested by both reindeer herding communities and the general public and is becoming more common, but the forest industry criticizes CCF for lower wood production. Mechanical site preparation (MSP) increases regeneration success and, thus, increases wood production in CCF. To reduce the conflict between forestry and reindeer husbandry, MSP in Sápmi should destroy as little ground lichen as possible. Today, there are no solutions for gentle and lichen-adapted MSP in CCF. Thus, there is a strong need to develop and test new technical solutions that increase regeneration success in a lichen-adapted way during CCF in Sápmi. We suggest that MSP solutions be developed which are gentle, work selectively and function in shelterwoods, gap cuts, and selection cutting stands. We envision that these solutions could fill the gap between the desired adaptivity on the part of the reindeer herding communities and the desired efficiency on the part of the forest industry. Such MSP technology would contribute to increased acceptance of CCF in the forest industry, higher biodiversity, and considerably reduce the conflict between forestry and reindeer herding communities.

As labour for manual tree planting becomes scarcer, regeneration costs are steadily increasing in Nordic forestry. Today's intermittently advancing tree planting machines provide excellent silvicultural results, but are expensive to operate because of poor productivity. In contrast, continuously advancing planting machines, thanks to high productivities, are increasingly being regarded as a solution to these runaway regeneration costs. The Silva Nova was a historical, continuously advancing tree planting machine with high productivity. However, Silva Nova's weaknesses included high labour costs (it required two operators) and the random nature of how it chose planting spots. In contrast, SuperSilva, a purely conceptual modernisation of Silva Nova, involves both automation and microsite identification to make the machine more efficient. We used discrete-event simulation to analyse the stocking rate and spatial distribution of tree planting with SuperSilva. The simulation results showed that introducing sensors for identifying suitable microsites will allow continuously advancing planting machines (like SuperSilva) to plant seedlings in a numerically and spatially adequate manner on moraine soils. Hence, these sensors will increase the competitiveness and versatility of tree planting machines. Unfortunately, such reliable and robust sensor technology (unaffected by a wide variety of operating conditions) is not yet commercially available.

Because of generally small log piles, loading forwarders during thinning is time consuming. The Assortment Grapple, an innovative grapple with an extra pair of claws which facilitates the handling of two assortments during one loading crane cycle, has been designed to decrease forwarders' loading time consumption. A standardized experiment was performed in a virtual thinning stand using a machine simulator with the objectives to form guidelines for working with the Assortment Grapple and to analyse its development potential. Four experienced operators participated in the study. According to the results, the Assortment Grapple's accumulating function is beneficial only when there are no remaining trees between piles loaded during the same crane cycle. In such cases, none of participating operators lost time, and 3 of 4 operators saved time notably. The problem with the remaining trees is the extra time required to steer the crane tip around them. Therefore, a harvester should place those log piles that are later to be forwarded together in the same space with no remaining trees between the piles. Furthermore, we recommend that the Assortment Grapple's usability will be improved by adding an own rocker switch on the forwarder's controls to command the extra claws.

Because todayâs tree planting machines do a good job silviculturally, the Nordic forest sector is interested in finding ways to increase the planting machinesâ productivity. Faster seedling reloading increases machine productivity, but that solution might require investments in specially designed seedling packaging. The objective of our study was to compare the cost-efficiency of cardboard box concepts that increase the productivity of tree planting machines with that of todayâs two most common seedling packaging systems in southern Sweden. We modelled the total cost of these five different seedling packaging systems using data from numerous sources including manufacturers, nurseries, contractors, and forest companies. Under these southern Swedish conditions, the total cost of cardboard box concepts that increase the productivity of intermittently advancing tree planting machines was higher than the cost of the cultivation tray system (5â49% in the basic scenario). However, the conceptual packaging system named ManBox_fast did show promise, especially with increasing primary transport distances and increased planting machine productivities and hourly costs. Thus, our results show that high seedling packing density is of fundamental importance for cost-efficiency of cardboard box systems designed for mechanized tree planting. Our results also illustrate how different factors in the seedling supply chain affect the cost-efficiency of tree planting machines. Consequently, our results underscore that the key development factor for mechanized tree planting in the Nordic countries is the development of cost-efficient seedling handling systems between nurseries and planting machines.

Factors affecting forwarding work are interesting because they can be used to better optimize forwarding routes and to predict costs. The main objective of this study was to investigate the association between driving speed and driving distance when forwarding. Data was automatically collected during 2.5 years from two large forwarders operating during final felling in central Sweden. Driving speeds for the work tasks Driving unloaded, Loading drive and Driving loaded were analysed using correlation, least-squares regression, and quantile regression. The results showed that speed and distance were strongly correlated for the work element Driving unloaded, while the correlation was weaker for Loading drive and Driving loaded. Possible factors leading to these results are as follows: longer travelling distances stimulate better planning and the establishment of better extraction roads; operators may feel stressed and drive faster as travelling distance increases; and finally, the relative influence of accelerations and decelerations decreases with increasing driving distance. Also, the use of quantile regression was successful and provided information that normal least-squares regression does not provide.

Crane work is the most time-consuming work element in forwarding. Hence, assist systems like boom-tip control are of interest. The first commercially available boom-tip control for forwarders was introduced in 2013. In this study we analysed whether replacing conventional boom control (CBC) with John Deere’s version of boom-tip control (named Intelligent Boom Control, IBC), increases crane-work productivity. We used data automatically gathered from 10 final-felling stands, covering typical logging conditions for southern, central and northern Sweden. Two John Deere 1510E and two John Deere 1910G forwarders were operated by seven experienced operators during the follow-up study, covering 1238 loads in total. A split-plot design was applied to isolate effects of the boom-control system being used (CBC, IBC). We found that using IBC for loading work (crane work and driving included) saved 5.2% of productive machine time compared to using CBC (p ≤ 0.05). The corresponding saving when using IBC for unloading work was 7.9% (p ≤ 0.05). Depending on geophysical factors, this corresponds to approximately 4% savings in productive machine time for forwarding as a whole, including pure transport (with and without load). Moreover, the study introduced in cut-to-length context a novel field-study design to collect a large follow-up dataset in the course of ordinary forwarding operations. We found the study design to be a cost-efficient way to combine the representativeness of conventional follow-up datasets with the ability to establish causal relationships. Establishment of causal relationships has traditionally been possible only through observational time studies or standardized experiments.

In mechanized forestry, much of the work is conducted by use of cranes, and recovering potential energy is a possible method to reduce energy consumption when using cranes for lift work. The objective of this study was to evaluate the capacity of a new »Energy-efficient hydraulic lift cylinder« (EHLC), which has a secondary cylinder built into its piston rod, to store potential energy from lowering the boom in the form of pressurized hydraulic oil in an accumulator and using the stored energy in the next boom lift. The EHLC was mounted on a forwarder, and manipulated to enable its use also as a standard cylinder. We then compared the EHLC and a standard cylinder in terms of function and energy consumption during repetitive boom lifts and lowerings. With the tested settings the EHLC saved up to approximately 9.4% of the energy consumed during the first part of boom lifts and up to 3.2% of the total lift energy. With possible further adjustments, such as optimization of the accumulator size, enlargement of the assisting cylinder diameter, and enhancement of the accumulator pressurization, but most importantly reduction in internal leakage, the current EHLC could have commercial potential.