Volume 46 No. 1

The use of hydraulic binder materials for the improvement of pavement subgrade has many implications for the surrounding ecosystem due to the possible leakage of alkaline compounds. The objective of this study is to evaluate the capacity of plants to remedy the subgrade affected by alkaline inclusion. To reduce the impact and return the subgrade to its original state, a phytoremediation process is studied. The impact of two materials commonly used for the subgrade improvement is analysed – fluid ash (slag) and lime+cement mixture. Three different mixes of plants – Mix A, Mix B and the native natural vegetation Mix N – are proposed. Totally 99 samples were collected and 990 specimens were chemically and geotechnically analysed and statistically evaluated. The success of phytoremediation process for both Mix A and Mix B can be observed. It is considerably higher for the undersurface alkaline inclusion than for the surface one. Mix B appears to be the best for fluid ash binder and Mix A for lime+cement mixture binder. It is worth noting that the native natural vegetation in Mix N also contributes to the phytoremediation process and that the appropriate plant selection – e.g. Mix A and Mix B – can accelerate this process.

Among various forest management activities, thinning is a prevalent treatment that affects tree growth and living biomass. Increased moisture and light availability may also enhance the mineralization of litter and dead wood organic matter, impacting soil carbon stocks. Thinning may also affect the services forests provide, including water production and nutrient cycling. The impacts of thinning on water yield and carbon stocks have been well documented around the globe while targeting mainly one of these ecosystem services. Our experimental paired catchment study covers both and puts forward long term results. We assessed the carbon stock changes caused by two slight thinning treatments together with the impacts on water yield in experimental paired catchments of 71.9 (W–I) and 77.5 hectares (W–IV) in Istanbul, Türkiye. The null hypothesis was that the slight thinnings did not affect the water yield and carbon stocks significantly. On the carbon stock part, we calibrated and parametrized the CBM–CF3 model with field measurements to simulate changes in carbon stocks of mixed deciduous forest stands. The intensities of the treatments (thinnings) were 11% and 18% of the basal area, performed in 1986 and 2011, respectively. We found that, while C stocks decreased by around 30 tons per hectare during the 1986–2020 period, the water yield was enhanced by approximately 25 mm/yr in the treatment catchment compared to the control watershed during the four-year post-treatment period. This amount of streamflow increase was around 10 percent of the average water yield of the catchments. It was concluded that there was a detectable increase in water yield during the following four years of the slight thinning treatments, while the reduction in abovegound carbon stocks continued for more than three decades.

Forwarders often load logs organized in large piles by modified farm tractors, skidders, animals, other forwarders, etc., but currently, there are no studies on how the different concentrations of logs affect forwarder performance in terms of time consumption, productivity, and costs in forwarding operations. A study was conducted in three locations situated in Bulgaria (sites A and B) and in southern Italy (site C): in site A the logs were spread in the stand, in site B they were concentrated in large piles at the roadside, whereas in site C the logs were organized at the roadside in piles of medium size. The average forwarder productivity in site A obtained at an average forwarding distance of 1780 m, an average payload volume of 9.83 m3, and an average number of grips of logs with the crane grapple, during loading (22.97) and during unloading (8.97) per cycle, is 10.43 m3·PMH-1 (PMH, productive machine hour) and 9.93 m3·SMH-1 (SMH, scheduled machine hour), respectively. In site B the productivity rate was lower than that registered by the forwarder operated in site A: 9.38 m3·PMH-1 and 8.81 m3·SMH-1, respectively, at an average forwarding distance of 3760 m, average payload volume of 15.04 m3, and a mean number of grips of logs with the crane grapple, during loading and during unloading, of 23.57 and 14.10 per cycle, respectively. With regard to site C, the average machine productivitiy was 12.39 m3·PMH-1 and 11.85 m3·SMH-1, travelling a mean forwarding distance of 1630 m, transporting a mean load volume of 13.63 m3, and performing an average number of grips of logs with the crane grapple, during loading of 26.52 and during unloading of 12.36 per cycle. The ratio between the number of grips of logs with the crane grapple during loading and unloading operations in site A is on average 2.56, but in site B it is significantly smaller – mean of 1.67, due to the larger number of logs in the grapple when loading from large piles. Site C shows a loading and unloading number of grips ratio intermediate between the two Bulgarian sites. This ratio is characterized by the concentration of logs in the stand. Concentration in larger piles results in a larger volume of grappled logs by crane, and hence, lower time for loading of the forwarder and higher productivity. The obtained results show that the dispersion of small piles of logs results in a smaller volume grappled, a greater number of crane cycles and a larger loading distance, which generally, increases loading time. The larger volume of logs in the crane grapple and the shorter loading distance, when the loading operation is carried out from larger piles at the roadside, lead to less loading time. Gross costs for forwarders were 65.14 € PMH-1 at Site A, 72.96 €·PMH-1 at Site B, and 85.58 €·PMH-1 at Site C. When the forwarders were productive, the costs were 6.35 €·m-3 in site A, 7.90 €·m-3 in site B, and 6.90 €·m-3 in site C.

Tracking roadside wood inventories is necessary for wood procurement. However, this operation is increasingly problematic due to the costs associated with reaching remote sites, labour shortage, and the methods providing limited information on the characteristics of the logs required for transport planning. To overcome these problems, an automated procedure has been developed in Arcmap to characterize individual wood pile inventories at roadside by using GPS points of forwarders, harvester production files, and the road network shape files. An inventory of the logs in the harvest area followed by a wood pile inventory at the roadside were made to evaluate how the procedure could trace logs from machine operating trail to predicted wood pile locations. The study was done at six harvest blocks in the Saguenay-Lac-Saint-Jean region in the province of Quebec, Canada. The procedure was not able to differentiate individual wood piles and aggregated several piles into predicted unloading areas. Results indicated a similarity index of 72% to manually inventoried wood piles. The similarity index could be explained by the low percentage of inventoried unpredicted wood pile lengths (3%) and a high percentage of overpredicted wood pile lengths (27%). The positive allocation rate could not be assessed at the level of the individual piles. On the other hand, the procedure properly allocated 96% of the logs to unloading areas. With the level of precision obtained, the developed procedure could be beneficial for managing the transportation of wood at the level of the road segment since it provides all the dendrometric data of the logs available for transport without requiring human intervention in the forest.

Today in many countries and regions, forestry sector deals with a considerable shortage of forestry workers and faces the serious challenge of ensuring a qualified and sustainable workforce. Current global processes and structural changes, such as emigration from rural areas, aging of the population, unfavorable age structure of existing employees, negative demographic trends (migrations, decline in birth rate, negative natural increase, etc.), lack of interest in the so-called 3D (dirty, dangerous and demeaning) jobs, low cost of labor and others, significantly contribute to such an adverse situation. Additionally, forestry work, especially wood harvesting, represents a very risky, professionally highly demanding and physically extremely intensive activity, which is regularly classified as one of the most dangerous occupations with a high proportion of serious injuries, fatalities and occupational diseases. For these reasons, the forestry profession is considered unattractive, and the job of a forestry worker undesirable. All of this makes finding the people interested in these jobs very difficult, and the task of ensuring the necessary workforce for all regular activities in sustainable forest management becomes very hard. In this paper, based on the surveys carried out in the Federation of Bosnia and Herzegovina (FB&H), i.e. evaluation of forestry workforce sustainability factors, and on the study of available strategic documents, policies and case studies, strategic directions aimed at strengthening the sustainability of forestry workforce were elaborated. The sustainability factors were observed in three categories related to: a) stronger recruiting in forestry, b) more successful retention of forestry workers, and c) higher work commitment of forestry workers. Established rankings, together with other findings, were used to define four separate strategic directions: (1) Direct financial strategy, which emphasizes direct monetary payments to workers and is oriented towards labor productivity, (2) Indirect financial strategy, which focuses more on providing indirect material gains to workers and the quality of performed work, (3) Educational strategy, aimed at the education and training of workers, and (4) Technical-technological strategy, aimed at increasing the mechanization in forest operations thus reducing the demand for labor. The paper elaborates the basic starting points and main characteristics (priorities, measures and activities, stakeholders, responsible authorities, etc.) of each strategic direction considering the possibility and conditions of their implementation in national forestry sector. The objective of the paper is to raise the required awareness of the forestry workforce issues, its position and status, and also to provide foundations for enhancing the attractiveness of forestry work and improving the overall sustainability of the forestry workforce. The results of the study point out the critical issues and provide valuable insights that can help in formulating effective policies and strategies for the future.

Quadratic mean diameter is a widely used stand parameter present in the stand inventory summaries, while the top stand diameter is rarely reported in the literature, mainly in relation to dominant stand height. Since the dominant stand height is usually determined from the tree height-diameter curve of the stand, it is important how the top tree assemblage, used to estimate dominant diameter, is defined. The main objective of our study was to assess the bias between differently defined dominant diameter estimates for monospecific plantations of various species, to model the dominant diameter as a function of quadratic mean diameter and other relevant stand variables, and to estimate its goodness-of-fit in predicting dominant diameter and dominant height.

We used data records gathered in sample plots in monospecific plantations of four tree species: Scots pine, Black pine, black locust and hybrid black poplar. We calculated the quadratic and arithmetic mean diameters of the 20% thickest trees in the plots, and the quadratic and arithmetic mean diameters of the trees, whose number corresponded to the 100 thickest trees per hectare. For each dataset, we analyzed the range and the distribution of the relative deviations calculated for each pair of dominant diameter estimates. For the Black pine plantations, regression models were developed for the two dominant diameter definitions, whose values differed most. Their goodness-of-fit was assessed from model efficiency and error statistics. The same model derivation procedure, applied to the Scots pine data, was followed by substitution of the predicted dominant diameter into a height-diameter model to assess the goodness-of-fit of the dominant height predictions.

The differences between the arithmetic and quadratic means, estimated from the same subsample of trees, did not exceed 2% in all cases. However, dominant stand diameters calculated as averages of differently defined largest tree collectives differed by as much as 35%. Regardless of its definition, the dominant stand diameter was adequately predicted by a function of the quadratic mean diameter alone or considering stand basal area as a second predictor. The models showed very good accuracy of model efficiency above 0.92, average absolute error below 8%, with 90% of the relative errors less than 15%. The predicted dominant diameter value can be used in a height-diameter model to estimate with confidence the dominant stand height of a monospecific forest plantation, allowing the forecast of the stand attributes based on dominant trees when only average stand variables are known.

The position and shape of the feed channel (FC) in low-power woodchippers significantly affect the way machine operators’ upper limbs move. The execution of operator’s movements can be accomplished in different working areas: comfortable, acceptable, or not recommended due to overloads in the musculoskeletal system. Three groups of male subjects from Central Europe, divided according to anthropometric dimensions from centile groups C5, C50 and C95, were selected to assess upper limb movement, by adopting a Motion Capture measurement method. The tests have shown that the limb closer to the FC (left hand in this study) carries out all the movements in the allowed zone (AZ), while between 79% and 96% of the limb movement is contained within the comfort zone (CZ). The right limb has a greater amplitude of motion outside the CZ working area – from 0% to 69% and for AZ – in the CZ can vary by up to 51%. It was found that commercial low-power woodchippers deployed in urban areas, typically induce overloads in the musculoskeletal system of the operator during the use. Based on the research results, the authors see the need to improve FC position adjustment for the operators of these machines.

The life and robustness of forest roads depend on their protection from the harmful effects of water coming into the road surface. In particular, the deterioration of the road surface affects the safe navigation of vehicles and traffic safety. This situation requires that the surface be stable on forest roads. The aim of the study is to examine whether surface deterioration (erosion and accumulation) on forest roads due to the drainage problem of water falling on the road surface can be minimized by open-top culverts and to determine their effectiveness. These are used in three separate trial blocks every 25 m (A parcels; total of 3 parcels), every 50 m (B parcels; total of 3 parcels) and control block (C). Volumetric erosion and accumulation in these blocks was compared by UAV for about 3 years and the effectiveness of the open-top culverts was examined by this method. A 500 m section of the forest road coded 001 of the Kardüz Forest Operations Directorate (Düzce/Türkiye) was examined in the study. As a result, erosion and accumulation in all blocks have been found to have a dynamic course. It was determined that this mobility was greater in the control block than in the blocks with open-top culverts installed at intervals of 25 m and 50 m. The mean Z values for the blocks showed that the deterioration in the control block (C) was higher than in the blocks with 25 m and 50 m open culverts. The volumetric deterioration rate was 5 times higher in the control block than in the block installed at 25 m interval (A plots) and 2 times higher than in the block installed at 50 m interval (B plots). Similarly, the areal deterioration rate was 3.3 times higher in the control block than in the block installed at 25 m interval (A plots) and 1.4 times higher than in the block installed at 50 m interval (B plots). These results showed the effectiveness of open-top culverts and it was also determined that the open-top culverts installed at 25 m intervals were more effective than the open-top culverts established at 50 m intervals. In addition, according to the statistical analysis, a statistically significant difference was found between the erosion volume in the blocks. Open-top culverts should be used against forest road surface deterioration and UAV technology should be used for deterioration detection.

This study examines the factors that influence the decision-making rationality of private forest owners (PFOs) when implementing salvage logging after large-scale natural disturbances. The literature suggests two main responses to large large-scale natural disturbances: performing salvage logging and no salvage at all. When salvage logging is carried out, two different strategies can be applied: clearing, i.e. all trees are removed, including damaged trees and standing survivors; and salvaging, i.e. damaged trees are removed but the surviving trees are left and some dead trees are left standing. In an online survey conducted in Slovenia in March and April 2022, responses were collected from 1515 forest-owning households. A logistic regression model was created to analyse the data and understand how socio-demographic characteristics, characteristics of forest property, forest management activities and the market influence their decisions. The results show that previous management activities and cooperation with service providers significantly influence PFOs' decision-making rationality to implement salvage logging. The study contributes to a nuanced understanding of the complex decision-making processes in forestry. Future research opportunities lie in investigating specific aspects of past management activities and understanding the dynamics in cooperation between different actors to develop customised policies for effective forest management after large-scale natural disturbances.

In Central European conditions, harvester use becomes more popular for broadleaved tree species, though there are still some difficulties with effective delimbing of satisfactory quality. Considering these issues, economic aspects are ultimately crucial when deciding on the use of harvesters and assessing the effectiveness of their productivity. The objective of the present research was to apply different harvesters in thinning of alder stands to determine their productivity level focusing on the use of tree trunk for logs. The study was carried out in alder stands under thinning where five different harvesters were used in nine stands, five of which were of coppice origin. Additionally, in six cases, harvesting was done after the growing season and in three cases during the growing season, when trees were covered with leaves. An average productivity was 14.42 m3 PMH0-1, with maximum values of 24.34 m3 PMH0-1 in a coppice stand, and 23.66 m3 PMH0-1 in a planted stand. Delimbing was carried out in the tree crowns with the mean diameter as small as 7.9 cm under bark, which shows very good use of the tree trunk for logs. It was also established that the thicker the tree, the bigger the top diameter of the last log, leading to bigger biomass production, e.g. for energy purposes, but also with smaller effectiveness of log processing.

Traction assistance of forest machines via traction aid winches has gained widespread application in steep-terrain forest operations as it can mitigate soil disturbance by reducing wheel or track slip of the assisted machine. Since slip affects machine operations in flat terrain as well, especially on fine-grained and moist soils, the effectiveness of traction assistance under such conditions was evaluated. At a forest site, a forwarder with a total mass of 28.6 t was driven over two plots in 15 passes. The machine travelled unassisted over one plot, while on the second plot traction assistance was manually adjusted to keep slip close to 0%. Wheel slip and winch tractive force were recorded during each pass, and rut depth was measured after each pass. Soil density was measured pre-impact and at three times after different traffic increments. Although the mean wheel slip was low even during unassisted travel, traction assistance was found to cause a significant reduction. While both a decrease in rut depth and soil compaction were observed with traction assistance, only the latter was significant after three machine passes. A potential influence of inhomogeneous soil reinforcement due to roots suggests repeating the experiment on a more homogenous soil.

The advanced age of logging business owners in the US South and their pending retirements has created uncertainty about the future stability of timber harvesting. Succession plans increase the likelihood of business longevity, but it is unknown how many logging business owners in the US South have one. In-person interviews of sixteen logging business owners aged 52 through 75 years were conducted in Georgia and Florida in 2022, focusing on business characteristics, employment, perceived challenges, profitability, and succession planning. Most owners had no written succession plan but did have contingency plans for short-term, unanticipated absences. Owners greatest challenges were trucking, insurance premiums, fuel costs, equipment pricing and availability, and labor. Loggers’ associations, forestry associations, and mill procurement staffs should be proactive in encouraging logging business owners to prepare succession plans.

Physiological workload during timber forwarder operations presents a heavy burden due to the unpaved forestry occupational roads, and steep terrain in Japan; however, the relationship between physiological workload and vehicle movement is not clear. To assess the workload of operating forwarders, changes in heart rate and vehicle movements were measured. Five male subjects aged 35 to 53 years were assessed. The subjects were tested twice while operating a forwarder with an empty load: first driving forwards, then driving in reverse. Three inertial measurement units were used to calculate travel speed, tilt angle, and turning speed, and heart rate was assessed using a wearable heart rate sensor. Vehicle movement and heart rate were synchronized every 10 s. The subjects’ average heart rates ranged from 69.09 to 87.63 bpm, which was higher than when traveling on paved forest roads. The physiological workload, based on %HRR results, was greater during reverse travel, possibly due to blind spots and road obstacles such as roots or branches. Additionally, %HRR increases with travel speed during forward travel; however, the %HRR remained high even at low speeds during reverse travel. Furthermore, forward travel tends to keep the vehicle level, whereas reverse travel involves bumps due to sudden operational changes. It is crucial to enhance machine performance and structure in the future to reduce workload, improve visibility, and minimize blind spots.

Natural and human-induced disturbances are major drivers of the decline and loss of vulnerable species worldwide. Among these, fires are particularly disruptive as they can devastate entire ecosystems. Assessing the likelihood and severity of such disturbances on plant communities is crucial for the management and conservation of biodiversity. This study aims to analyze fire susceptibility using the Maximum Entropy (MaxEnt) model to evaluate the potential impacts of fires on the biodiversity of a lowland forest in Azerbaijan. The research was conducted as part of the project on the evaluation of Red Book species in Azerbaijan based on IUCN categories and criteria. In this study, 21 rare plant species found in the Samur-Yalama National Park (SYNP) were assessed for fire susceptibility, as they have been significantly affected by fires in recent years. The fire susceptibility analysis included 12 driving factors, categorized into topographic, vegetation, and climatic factors, and identified 564 wildfire incidents. Model performance was evaluated using the AUC value, which was 0.855, indicating good model accuracy. Fire susceptibility was classified into three categories: low, moderate, and high. According to the results, 12,642 hectares (60.82%) of the SYNP area fall under low susceptibility, 5532 hectares (26.62%) under moderate susceptibility, and 2611 hectares (12.56%) under high susceptibility. Rare plant species in SYNP were evaluated based on their fire susceptibility. It was found that Alcea kusariensis (Iljin ex Grossh.) Iljin, Anacamptis morio subsp. picta (Loisel.) Jacquet & Scappat., Equisetum hyemale L., Orchis purpurea Huds., Pinus brutia var. eldarica (Medw.) Silba, Platanus orientalis L., Punica granatum L., and Quercus castaneifolia C.A.Mey are located in areas classified as having high susceptibility.