Volume 46 No. 2

Ground-based forest operations can produce an intense level of soil disturbance and hamper the growth of seedlings. However, previous studies on the topic of seedling growth performance on the skid trail network showed high variability and non-uniform responses. Therefore, a multivariate meta-analysis was applied to investigate the effects of soil disturbance after ground-based forest operations on the aboveground and belowground growth of seedlings. We further assessed the effects of the following moderators: type of regeneration, type of stand, number of years since the forest operations, mass of the machine used, number of machine passes in the investigated skid trails, and the increased soil compaction in the skid trails. The results supported our hypothesis that ground-based forest operations had a greater effect on the growth of broadleaf species and natural regeneration. This was, however, mostly true for belowground growth, that was typically more affected than aboveground growth. We discovered that there is a recovery in seedling biomass and lenght following harvesting, but this is a long process that requires about ten to twenty years to begin. We found that the number of machine passes and the machine mass did not directly correspond to a higher level of impact, indicating that the actual disturbance drivers are more complicated interactions that occur among the machine, the way in which forest operations are carried out, and the soil properties. It was finally demonstrated that soil compaction was the primary cause of disturbance to seedling growth, primarily affecting belowground biomass and lenght. In particular, we identified a minimum threshold of a 30% increase in soil bulk density to observe statistically significant negative effects on seedling belowground growth. Soil compaction proved to be the main factor that can jeopardize the development of forest regeneration in the skid trails. This suggests that the same best management practices that are used to reduce soil compaction caused by machinery should also be used to reduce the detrimental effects of ground-based forest operations on seedling development. As future research directions, long-term studies are recommended to assess the recovery process dynamics. Moreover, more research on broadleaf, natural regeneration, and Cut-to-Length machinery is strongly suggested.

The substitution of petrol-powered chainsaws with battery-powered ones has still not taken place in professional forestry. With the latest battery-powered chainsaws, performance is not an issue anymore, but energy storage and recharging still are. Nevertheless, there are some ergonomic points where battery-powered chainsaws tower over petrol-powered ones. This work aims to measure, evaluate, and compare hand-arm vibration between two comparable chainsaws, one petrol, and the other battery-powered. Stihl MS 261 C-M and Stihl MSA 300 C were chosen for this task. The cutting measurement was performed on a wet trunk of sessile oak (Quercus petraea) with a diameter of 30 cm, and on thinner branches (<7 cm) in the canopy at the same felled tree. Time data that represents the ratio of chainsaw handling elements within effective working time in cutting and processing was obtained from previous research. Vibration magnitude was measured in compliance with ISO 8041-1:2017, ISO 5349-1:2001, and ISO 5349-2:2001 standards. The results regarding vibration total value (ahv), daily vibration exposure (A(8)), and time to reach exposure action value (EAV) and exposure limit value (ELV) proposed by EU Directive 2002/44/EC imply higher magnitudes on the rear handle and higher exposure of the right hand for both types of chainsaws. For petrol-powered chainsaw, results for measured vibration magnitude are 4.13 m/s2 for the left hand, 4.72 m/s2 for the right hand, and for battery-powered chainsaw 2.18 m/s2 for the left hand, and 2.82 m/s2 for the right hand. Daily vibration exposure is drastically lower when using a battery-powered chainsaw (A(8)=1.2 m/s2 – left, A(8)=1.5 m/s2 – right), likewise, the time to reach EAV and ELV is many times longer. The current state legislative restriction (Ordinance on Occupational Safety and Health in Forestry 1986) should be revised with the aim of increasing the effective working time because, according to the results of this work, it would be justified.

There are about 230,000 km of forest roads in Sweden, and maintenance and construction costs for forest roads per harvested cubic meter of wood is increasing. This is to some extent caused by increased demands for precision in delivery of fresh wood cut to customer specifications, shorter periods with frozen roads, increased vehicle weights and an ageing forest road network. Although many roads are constructed using the Swedish Forest Agency’s Guidelines, deviations are made to reduce construction costs. Further, short planning horizons reduces the period of settling, intended to allow the road to dry and consolidate under its own weight. In northern Sweden, central tyre inflation systems are used to reduce road wear from logging trucks and increase the period a road is accessible for traffic with logging trucks. To reduce road costs, the industry needs efficient road building methods and ways to reduce road wear. Thus, they want to know how thinner surface layers influence road wear and if reduced tyre pressures can help to reduce road wear on such roads. The aim of this study was to compare rutting by vehicles with low tyre pressures to rutting by vehicles running with standard highway tyre pressures on forest roads with thin surface layers.Three test roads, each divided into six sections with systematical sampling points for measurement of rut depth and road strength, were built. The test roads were trafficed by a fully laden CTI equipped log truck and trailer. Low tyre pressures were used on one side of the road and standard pressures on the other. Rutting was measured throughout the study. Reduced tyre pressures reduced rut development on two roads, while no differences could be found on the road that had not dried prior to testing. The positive effects of reduced pressures were largest on the best built road sections. The effect of thin aggregate layers should be further studied. This study failed in that sense as the variability in gravel thicknesses was to large within sections. Although the need to access the road may be high, access should not be approved until the terrace has dried and settled. Road wear can be mitigated by using CTI equipped trucks, but not on roads of too low quality.

The harvesting of low-value trees, primarily utilized for energy production, demands heightened productivity and reduced costs, necessitating the adoption of mechanized methods. Excavators are frequently employed in mechanized harvesting due to their affordability (often being used machines) and high adaptability. However, their operation often results in tree damage when swinging the upper structure. Consequently, recent advancements have led to the development and utilization of machines with smaller footprints, primarily applied in urban settings, aiming to enhance maneuverability.

This study aimed to analyze the operational and environmental benefits of employing reduced-tail swing excavators in forestry operations in contrast to conventional tail swing excavators. In thinning operations, the productivity of the reduced-tail swing excavator surpasses that of the conventional tail swing excavator by 18.5%, accompanied by a 41.8% reduction in fuel consumption. Moreover, the reduced-tail swing excavator exhibits a 41% decrease in energy consumption, resulting in a notable 65.8% reduction in CO2 emissions compared to its conventional counterpart. Additionally, the hourly operational cost is 10% lower than that of the conventional tail excavator.

While comparing the performance of both machines in clear-cutting, the differences observed are less than 5% and deemed statistically insignificant. Hence, it can be inferred that reduced-tail swing excavators present a viable alternative to conventional-tail excavators.

This study presents a novel, structured optimization approach for incorporating multiple ecosystem services (ES) into long-term strategic and tactical forest management planning. We provide a new and improved framework for forest planning based on ecosystem values of education, aesthetics, cultural heritage, recreation, carbon, water regulation, and water supply. First, the suitability values of seven ecosystem services (ES) were estimated to produce timber harvest and store carbon under fifty potential treatment schedules over a 100-year planning horizon. Then optimization was applied to maximize future utility values derived from values of ES that can be developed with treatment schedules and using the weights of the Sustainable Development Goals (SDG). Finally, the model defined ES functions that were weight-adjusted to select a successful scenario. Thus, we demonstrated that our approach could generate the optimal future suitability value of ES for long-term forest planning compared to the current value of ES. The results showed that the ES that is most affected when harvest demand and harvest flow constraints change is carbon. The value of other ES did not change when scheduled timber volume changed, and as a result we suggest that standing volume and growth increment be considered as criteria used to determine the future value of other ES. We found that the development of suitable value-effective management strategies for securing forest ES values in future stand developments was possible while also achieving other goals and while also being constrained by operational considerations. Our study therefore contributes to ongoing debates about the management of ES.

Accurately determining soil classes in forest road constructions holds paramount importance in mitigating inconsistencies and disputes in cost and progress payments during and after construction. This study aims to explore the potential of geophysical methods (seismic refraction tomography – SRT, active multichannel analysis of surface waves – A-MASW, electrical resistivity tomography – ERT, and ground-penetrating radar-GPR) in determining the rippability classifications of geological units to be excavated in new forest road constructions, as well as vertical stratification and lateral lithological facies boundaries. This study also conducts a comparative analysis between the cost and progress payment values obtained through classical methods. The study area encompasses six new forest road alignments identified within the Trabzon Regional Directorate of Forestry investment program in Türkiye. For assessing the reliability and validity of the measurements, the Cronbach's alpha test was employed. The equality of the measured variable variances across groups was determined using the Levene’s test, and to determine the source of differences among groups subsequent to the measurements, the Dunnett’s test from multiple comparison tests was utilized. The study revealed disparities between the excavation volumes/class ratios/approximate costs calculated based on soil classes in new forest roads by the forestry administration, the excavation volumes/class ratios/approximate costs realized upon construction completion, and the excavation volumes/class ratios/approximate costs calculated within the scope of this study. The results obtained demonstrated that the combined utilization of SRT, ERT, and A-MASW methods enhanced the reliability of soil characterization and rippability classification when determining rock rippability characteristics in forest road constructions. In this context, it is considered that the additional cost incurred by geophysical engineering measurements can be justifiably met, given the potential benefits, which include more rational planning of investment budgets and cost analyses in new forest road constructions, as well as the facilitation of savings in time, labor, and capital. Furthermore, these measurements are anticipated to contribute to the resolution of potential disagreements between contractors and forestry administrations.

The evaluation of soil impact of forest operations has been done using professional platforms and time-consuming traditional methods. However, today low-cost LiDAR technology may achieve a potentially effective 3D mapping of soil impact. This work aimed at evaluating the accuracy of smartphone and GeoSLAM Zeb-Revo LiDAR platforms, by comparing the scanned data to a manual reference. Manual measurements using a tape were taken on four sample plots to obtain reference data, followed by scanning with LiDAR platforms to obtain data in the form of point clouds. CloudCompare was then used to process the LiDAR data, and the Bland and Altman’s method was used to check the agreement between the manually taken and scanned data. The results showed that the low-cost LiDAR technology of iPhone has the potential for mapping and estimating soil impact with a high accuracy. The Mean Absolute Error was estimated at 0.64 cm for the iPhone measurements with SiteScape App, while the figure ranged from 0.68 to 0.91 cm for the iPhone measurements done with 3D Scanner App. Zeb-Revo measurements, however, had an estimated MAE of 0.61 cm. The Root Mean Squared Error was estimated at 0.95 cm for the iPhone measurements with SiteScape, whereas the iPhone with 3D Scanner App and Zeb-Revo measurements produced RMSEs of 0.99–1.51 cm and 1.11 cm, respectively. These findings might provide the basis for further studies on the applicability of low-cost LiDAR technology to larger sample sizes and different operating conditions.

Direct quality estimation studies of forest roads using remote sensed data are still rare. Research focussing on deriving indirect factors about road quality such as wetness or soil bearing capacities are prone to uncertainty of estimates. Altough processes of direct 3D roadsurface measurements and assesements exist, those systems mostly rely on ground-based collection methods, which are laborious and expensive for big forest road networks. Because of the increased quality of airborne laser scanned data (ALS) over the last decades, it was researched how this development may be used for forest road infrastructure assesement. The present study uses ALS data to estimate the occurrence of road damage in the form of concave depression. Maximum damage depth measurents were collected in a test area near Ilomantsi (Finland) and used to fit a linear mixed effect model to a subset of variables derived from ALS data as fixed factor and location as random factor. Simultaniously, depth measurements were carried out in a digital terrain model and compared to the real depth values to gain insight into maximum reachable accuracies. It was detected that ALS data tend to underestimate road damage depressions, limiting results in follow up models. Our results also indicate that road location could explain up to 30% of the variablity in our models. In the most optimal case, a linear mixed effect model could achieve an R2 of 0.87 with and 0.66 without the random factor having a residual mean standard error (RSME) of 1.9 to 2.7 cm on unvegetated forest roads. The best performing model determined in our study using ALS derived variables reached an R2 of 0.58 and 0.44 with an RSME of 1.8 to 2.4 cm. The work conducted gave insight into the culprits and limits of road depression depth estimates using ALS data. Future research should be conducted to change the scope of the analysis to an evaluation of bigger road segments and to investigate how road location could be utilized to achieve results with better accuracies.

Rope end connectors are a cricital component for attaching logs and trees to winches in ground-based harvesting operations. Knowing their strength not only in theory, but also under real working conditions, is crucial for selecting and dimensioning suitable end connectors in order to ensure compliance with the respective safety factors. Currently, there are limited published testing data on the strength and failure types of various end connectors. Furthermore, no information is available how end connectors perform if they are used in combination with rope sliders. Thus, different end connectors suitable for 12 mm steel wire ropes were developed and break-tested under conditions close to reality to determine their suitability for logging operations, considering different load type combinations by including rope sliders. The aim of the study was to give an overview of the suitablity of end connectors and different rope slider – end connector combinations for ground-based harvesting operations and to become aware of where and at which forces failures occure first. The results show that if the load is only attached directly to the end connector, turn-back eyes and wedge sockets provided consistent performance in breaking strengths. Attaching loads only to rope sliders led to siginifcant reductions of the end connectors performance in general. A comparatively high loss of performance was assessed if turn-back eyes were used in combination with rope sliders. This raises the question of their suitability as an appropriate end connector in ground-based logging. The most common cause of failure was found to be rope breakage, which mainly occurs due to the strong deflection angles of the rope during pulling.

In anticipation of the utilization of logging residues and small-diameter trees after the completion of the Feed-in Tariff Scheme for Renewable Energy (FIT) in Japan, this study (i) calculated the available amount of unutilized forest biomass resources over a long term by using the developed »regional forestry operations management model« and (ii) estimated the period and the ratio of the generation of small-diameter trees during cleaning and pre-commercial thinning operations to the whole biomass resources. These analyses revealed that in the first 60 years, the clearcut and reforestation of 763 ha of planted forests (average age 66 years) with the labor input of approx. 2000 man-days per year were promoted, and thus 71% of the whole area was returned to the regular harvesting cycle. During that period, the average amounts of log production and biomass generation were 7184 m3/y and 875.6 Mg/y on a dry-weight basis, respectively. During the next 60 years, when the clearcut of older, high–accumulation forests and the subsequent reforestation were stabilized, the average amounts of log production and biomass generation under sustainable forest management were 5239 m3/y and 774.8 Mg/y on a dry–weight basis, respectively, exhibiting lower amounts than those of the first 60 years. Small-diameter trees were generated by cleaning and pre-commercial thinning operations stably from 16 years after the beginning of clearcut and reforestation. Especially after 61 years, the average annual amount of small-diameter trees generation accounted for around 10% of that of the whole biomass resources and more than 50% of that of unutilized thinnings.

Timber harvesting tends to generate controversy in society. Some emphasize the benefits of obtaining renewable resources, while others lament the loss of forest carbon stocks and the resulting emissions. However, as long as the wood does not decompose, it continues to store carbon. Consequently, buildings and goods made of wood become carbon sinks. To illustrate this carbon storage potential, we developed an application that calculates the carbon footprint of mechanized timber harvesting using the production reporting input files »harvested production-hpr« and »machine operating monitor-mom« in the StanForD format generated by harvesters and forwarders. The »HarvestCO2-App« is a free, user-friendly web application for forest owners, machine operators/owners, and policymakers, programmed in R with an R Shiny user interface. The app aims to raise awareness of the carbon storage potential of wood use by providing a quantitative basis for discussion. The app also inquires about the conditions under which timber was harvested. By evaluating this information alongside the calculated carbon footprint, it will be possible in the medium term to conduct a sensitivity analysis of the impact of individual factors on emissions.

Traditional methods of determining cable corridor layouts often rely on less accurate tree maps based on forest density estimates and satellite imagery, which can lead to designs that rely on infeasible corridors, undermining their reliability. In our previous research, we used LiDAR forest maps to calculate highly realistic cable corridors in steep terrain. We then used a multi-objective optimization strategy to determine an optimal combination of possible cable corridors, taking into account costs as well as ergonomic and environmental factors. The optimization process is however not easily accessible to users not familiar with mixed integer linear programming approaches. To make the optimization process more accessible to forestry professionals, we have developed an interactive interface to support the layout planning process. This interface provides an interactive overview, a 3D perspective of the current layout, and detailed information on costs and metrics of the current cable corridor layout, facilitating the comparison and modification of different corridor layouts. The interface was evaluated by three subject-matter experts and their suggestions were incorporated into the presented version. The resulting tool can help experts use optimized cable corridor layouts in the planning process, and represents another step towards the digitalization of forestry.

Terrain roughness and local unevenness are included in the classifications of technological accessibility of stands, which are the starting point for functional classifications. The aim of research was to determine the impact exerted on the time consumption of timber harvesting and forwarding by linear terrain unevenness remaining after soil preparation for planting in the form of trenches and ridges with a depth ranging from 0.2 m to 0.6 m. The research was conducted in pine stands where early thinning was being carried out applying harvesters, forwarders and agricultural tractors with forestry trailers. The share of main work time and complementary work time for harvesters amounted to approx. 50%, of which delimbing and bucking accounted for 35%, and tree felling for 15%. The times of forwarding and unloaded journeys amounted to 28% for forwarders and were shorter by approx. 17% as compared to forest trailers. The share of loading and unloading times amounted to approx. 50%. Higher moving time was noted in the case of harvesting in stands with deeper linear unevenness of the terrain and when machines ran on skid trails perpendicular to unevenness. In the Eco Wood land accessibility classification applied in forest practice, we propose the use of a new factor, linear unevenness of terrain.

Excavator-based shovelling machines can be used on steep terrain to improve the safety and productivity of cable yarder extraction. Shovelling felled timber across to a yarding corridor limits the number of line-shifts required, and feeding the grapple carriage reduces cycle time and increases average payload. The study determined the productivity, utilization and time use of four excavator-based shovelling machines feeding a cable yarder operation using a grapple motorized carriage at four different sites in New Zealand’s South Island. The four machines were owned and operated by four different contractors, but they all worked on end-of-rotation radiata pine clearcuts. Productivity varied from approximately 25 to 100 m3 per hour, including waiting time for the grapple carriage to return, but excluding all other delays. Piece size had the strongest impact on productivity. Mean utilization was 61%. 20% of shovel worksite time was spent engaging with productive work other than feeding the grapple, such as felling, shovelling or tidying up the cutover.

Sensor technologies for monitoring danger zones during harvesting operations are not yet widely adopted, despite their potential to significantly enhance occupational safety. The objective of this study was to evaluate the performance of an ultra–wideband (UWB) sensor for detecting people in the danger zones of motor–manual harvesting operations. This was done to determine whether the system performance in practical use matches the results of a prior prototype test. The UWB sensor was deployed during three types of forest operations: thinning, clear-cutting, and overstory removal. Danger zones were defined as a circle with a radius of 1.5 times the top height of the stands: 21.00 m danger zone for thinning, 42.00 m for clear-cutting, and 46.50 m for overstory removal. Key metrics analyzed included detection distances, detection rates, interruptions in signal reception, and optimal sensor configuration. The results indicated mean detection distances of 19.80 m (90% Interval: 15.80–21.00 m) for thinning, 36.80 m (90% Interval: 23.70–42.00 m) for clear-cutting, and 39.00 m (90% Interval: 30.60–46.50 m) for overstory removal, with detection rates remaining stable across operations. The sensor system demonstrated its potential as a valuable tool for improving occupational safety.