Manual Felling Research Articles

Determining occupational exposure to inhalable wood dust in motor manual felling and processing

ABSTRACT The occupational exposure to softwood and hardwood wood dust was determined during forestry work in timber stands. In the determination of inhalable wood dust, three tree species (Fagus sylvatica, Quercus sp. and Pinus brutia) and three chainsaw operating parameters were taken into account (in total six assessment indicators). The first operating parameter was the chainsaw operating under normal conditions (regular chain sharpening). The second and third operating parameters were improper chainsaw maintenance (irregular chain sharpening) and low throttling pressing (operating the chainsaw at low engine speeds), respectively. The determination of inhalable wood dust concentrations from the ambient air was performed using the Inhalable Organic Matter (IOM) sampler, manufactured by SKC Button Sampler (Dorset, United Kingdom). Out of a total of 108 concentration cases of inhalable wood dust, 44 (40.74%) showed concentrations greater than 3.00 mg·m−3, while in 10 (9.26%) cases, the dust concentration exceeded 5 mg·m−3. The eight-hour time-weighted average exposure to wood dust ranged from 0.99 mg·m−3 to 12.52 mg·m−3, with an average of 4.22 mg·m−3. The results indicated that the increase in wood dust concentration was dependent on improper chainsaw maintenance, while low throttling pressing reduces dust concentration levels. Additionally, an increase in wood dust concentration was observed in species with thick bark (Pinus brutia and Quercus petraea).

A Stochastic Production Frontier Analysis of Factors That Affect Productivity and Efficiency of Logging Businesses in Virginia

Abstract Understanding the effect of the relationship between timber harvesting attributes on loggers’ productivity and efficiency is crucial for the feasibility and expansion of sustainable forest management and logging. We applied a stochastic production frontier model to firm-level operational data collected from 202 loggers in Virginia, United States, in 2019. Logging equipment value, physiographic region, tract area, number of workers and crews in the woods, college education level, and harvest type statistically increase harvesting productivity. Harvesting productivity in the Coastal Plain was the greatest of all physiographic regions, and pine clearcut productivity was statistically greater than that of hardwood thinning. On the other hand, manual felling reduces harvesting productivity. We found an average efficiency rate of 67% among firms in our sample, which is similar to that found in the literature. The estimated values can show factors that improve forest harvest productivity through better planning and investments while improving the sustainable use of inputs and resources. Study Implications: We empirically analyzed factors affecting logging productivity and efficiency in the southern US state of Virginia. Increased productivity was associated with working in the Coastal Plain physiographic region, investing in logging equipment, increasing the number of workers and crews in the woods, increasing pine clearcut as opposed to hardwood thinning, choosing optimal harvesting tract size, and having a college education as opposed to no high school degree. Manual felling reduces harvesting productivity, and average BMP implementation time does not affect harvesting productivity. Our results can be used as a guide in planning future decisions to increase logging productivity.

Sustainable use of forests

Sustainable use of forests

Comparison of harvesting productivity, cost, and residual stand damages between single-tree selection thinning and mechanized line thinning using a small-scale grapple-saw

Considerable amounts of noncommercial materials generated from thinning treatments remain unattended on the site because the value of small-sized timber is lower than overall thinning operation costs in South Korea. In addition, thinning operations with conventional and mechanized harvesting systems often cause severe physical damage to residual trees. In this study, therefore, we compared and analyzed the harvesting productivity, cost, and residual stand damage between single-tree selection thinning (SST) and mechanized line thinning (MLT) systems on conifer plantation forests. For conventional SST, ground skidding (uphill/downhill) was performed using a tractor winch after manual felling and bucking. The MLT consisted of mechanized felling, downhill shovel logging, and processing with a small-scale grapple-saw for the fourth double row (MLT1) and the third row (MLT2) thinning section. The MLT system was more productive and cost-effective in performing thinning treatment and collecting thinning materials than SST. The MLT1 and MLT2 costs were 81.4% and 70.6% lower than the SST cost ($77.6/m3), respectively. The residual stand damages of the SST (3.4%) were lower than those of MLT1 (4.8%) and MLT2 (21.2%); however, there was no significant difference in residual stand damages between two thinning systems (p > 0.05). Therefore, forest managers should consider the use of MLT system to reduce thinning costs and efficiently produce thinning materials for their thinning operations. However, operators still need to be careful felling and extracting operations to reduce the residual stand damages for thinning treatments.

Knowledge Retention and Changes in Licensed Chainsaw Workers’ risk awareness

Work with chainsaws is hazardous and felling trees is the activity with the highest risks for injuries and fatalities. While industrial forestry is increasingly mechanized, manual felling is still the main work method for private, small-scale forest owners. During this work, the workers’ safety heavily depends on their skill and safe practice, so training is presumably important for preventing injuries and reducing fatalities. Unfortunately, private forest owners have been difficult to reach with this kind of safety intervention. Moreover, target chainsaw users are not likely to repeat the training very frequently. Hence, the training must both be effective and be so for many years to come. This paper addresses the knowledge retention and self-reported changes in behaviour of 682 chainsaw users who passed the exam for the Swedish chainsaw licence 1, 3, 5, 7 or 9 years previously. Acquisition of the licence resulted in a strong increase in 98% of the participants’ risk awareness and safe work practices. Less than half (45%) of the participants passed a re-test equivalent to the theoretical examination for the chainsaw licence. Private forest owners performed somewhat better than employees did. The main indicator of retained knowledge of safe chainsaw handling was frequency of practice the previous year. After one year, the test results did not deteriorate with additional time. Based on those results, the best practice is to ensure regular usage of the chainsaw and refresher training when the chainsaw has not been used for a year.

Light and regeneration patterns following silvicultural gap establishment in Quercus dominated stands of the northern Cumberland Plateau, USA

We assessed short-term light and regeneration dynamics following silvicultural gap creation in intermediately productive oak (Quercus)-dominated stands of the Northern Cumberland Plateau, USA. We established 12 experimental units comprising a harvest gap (30-m radius) and a matrix zone extending 30 m beyond the circumference of the gap. Midstory removal was performed using manual felling and chemical deadening within the matrix zone of six experimental units, while those of the other six units remained undisturbed as controls. Belt transects extending 60 m from the gap center to the end of the matrix zone were delineated within each unit to quantify spatial light patterns and regeneration dynamics of oaks and woody competitors. Mean light transmittance ranged from 86% full sun at the gap center to<10% at the outer margin of the matrix zone. Light transmittance decreased from approximately 70% full sun within the gap at 10 m from the gap edge to 20% full sun at 10 m within the forest matrix. Two-year height growth and total heights of oaks were greatest within the gap interior and decreased toward the gap edge and subsequently into the adjacent forest matrix. We observed no statistical differences in light or regeneration patterns between control and midstory removal forest matrix zones. After two years, woody competition from non-oak stems, particularly yellow-poplar (Liriodendron tulipifera L.), was high within the gap interior, and >50% of non-oak stems were taller than the average oak seedling (50 cm). At the gap edge and within the adjacent forest matrix, <20% of non-oak stems were taller than 50 cm. Light conditions fostering taller oak reproduction and reduced rates of overtopping competition identify the gap edge environment as a zone of competitive oak reproduction within which future regeneration efforts may prove effective.

The Felling of Hung Up Trees—A Work Safety and Productivity Issue

Research Highlights: The felling of hung up trees is considered by literature in the field as an activity with a high injury risk. The low work productivity in the felling of hung up trees is wrongly cited by workers in order to justify various more or less safe work techniques. Background and objectives: The purpose of this paper was to determine work productivity in the felling of hung up trees when this activity has a well-defined structure with stages and specific activities that would allow workers to assess injury risk correctly. In addition, this paper aims to identify the moment when workers should give up the manual felling of hung up trees with a hand winch and start using specialized logging equipment. Materials and methods: The research was conducted in the Eastern Carpathians in a spruce (Picea abies (L.) H. Karst.) tree stand where clear cutting normally takes place. A single team of workers was used consisting of two chainsaw operators—a main one and a secondary one. This team had a high level of qualification and experience in the operations performed. For the felling of hung up trees, the technique based on rotating the tree around a pivot with a hand winch was used. Time was measured in seconds by using the continuous time study method. Results: The results indicated that work productivity decreases with the number of times the traction line needs to be repositioned. It decreases from 3.477 trees·h−1 (in trees where no repositioning is necessary) to 1.402 trees·h−1 (when the repositioning takes place twice). In trees that needed the repositioning of the traction line, safety rules were broken in the following ways: crossing over the tensioned cable of the traction line, the main chainsaw operator being positioned inside the triangle formed by the hung up trees and the anchorage points of the pulley and the hand winch as well as the operator being positioned very close to the hung up tree stem base while the latter is being tied. That is why, if the repositioning of the traction line is necessary, the question is—would it be better to give up the manual felling of hung up trees and start using specialized equipment? Conclusion: The felling of hung up trees must be regarded and understood, first and foremost, through the perspective of reducing injury risk and protecting workers. Thus, the work productivity of 3.477 trees·h−1 can be considered acceptable for trees that need no extra repositioning of the traction line or when the time consumed does not go over 17 min·tree−1.

Comparison of A Cable-Based and a Ground-Based System in Flat and Soil-Sensitive Area: A Case Study from Southern Baden in Germany

The results of this study showed that the application of cable-based systems in flat terrain must not necessarily be more cost intensive than its application in other terrains. In recent years, criteria other than purely economic ones have been taken into account in forest management decisions, with the aim of avoiding ecosystem damage and promoting better ecosystem services. Since precipitation in winter is becoming more intensive and weeks with frozen soils are becoming rare, one option might be the use of cable-based instead of ground-based extraction systems. Both vary in terms of economy and flexibility. Thus, it is important to make reliable estimates of potential costs and benefits before an operation is conducted. The aim of this study was to analyze a cable-based and a ground-based extraction system that could be applied to a forest stand in a flat and soil-sensitive area. The study, based on a cable-based operation, was conducted in a mixed forest stand that was vulnerable to traffic. Furthermore, we modeled an alternative operation focusing on a ground-based system, addressing the soil vulnerability by considering manual felling, processing, and use of a combi-forwarder for extraction. In the cable-based system, yarding productivity was high (20.3 m3ub/PMH15) due to several reasons, such as a high share of larger dimension timber, the fact that heavy timber was partially de-limbed and processed motor-manually in the stand, the fact that a mini forestry crawler was used for pre-winching the material and finally due to the experience of the operators. Resulting costs for harvesting and extraction were on average €27.8/m3ub. In the ground-based system, costs were on a comparable level (€28.30/m3ub). In our case, the application of a cable yarder in flat terrain was a good alternative and should be considered in future forest management to support environmentally friendly operations and allow independent planning of the operation.

Assessing the impacts of log extraction by typical small shovel logging system on soil physical and hydrological properties in the Republic of Korea.

Typical small shovel logging system, using manual felling and extraction by small crawler excavator with grapple and crawler carriers, is the predominant logging method in the Republic of Korea, due to the associated high productivity. The trails with ground pressure and one more passes of the shovel and carriers may lead to soil compaction. However, impacts of these bunching-extraction technologies on physical and hydrological properties of soils are not well known. The main objectives of this study were to: (1) determine the bulk density, porosity, and saturated hydraulic conductivity of soils in logging operation areas with three different disturbance types (i.e., undisturbed areas [UAs], bladed trails [BTs], and skid trails [STs]), and (2) compare soil compaction between these disturbance types. The most intense compaction occurred within BTs and STs, with increased bulk density and reduced porosity and hydraulic conductivity. Soil bulk density increased by 27–53% at all depths in BTs and STs compared to UAs, while porosity decreased by 23–49%. On average, saturated hydraulic conductivity at depths of 0–20 cm decreased from 337.5 mm h−1 to 30.5 mm h−1 in the most compacted sections of BTs and STs. Skid trails, which are characterized by trail construction and frequent vehicle movement, also caused greater impacts on soil compaction than BTs. This study provides useful insights to aid forest consultants and field managers in planning more environmentally sound mechanized logging operations.

Soil Disturbance Effects from Tethered Forwarding on Steep Slopes in Brazilian Eucalyptus Plantations

Traditional timber harvests on steep slopes have been conducted through labor-intensive and sometimes environmentally impactful methods, such as manual felling with chainsaws and extraction using bladed skid trails, winching, or cable yarding. Ground-based mechanized harvesting and primary transportation methods such as cut-to-length harvesters and forwarders have emerged in some parts of the world as low-impact, safe, and efficient alternatives to the aforementioned systems. However, when mechanized operations are used on steep terrain, problems such as poor stability, loss of traction, and increased soil disturbance can occur. Tethered or winch-assisted logging practices are being tested and applied in several countries to adapt to challenges associated with operating equipment on steep slopes while minimizing environmental impact. To better understand the feasibility of these systems, we conducted a designed experiment to quantify changes in soil properties and predicted erosion resulting from varying numbers of passes and payload levels by a forwarder operating on slopes ranging from 27 to 38 degrees. The machine was equipped with two different track configurations, tethered by either a machine-mounted or self-contained winch, in eucalyptus plantations in Brazil. On low slopes, bulk density significantly increased, but it did not increase on steeper slopes; this demonstrates traction winches’ effectiveness at reducing concentrated ground pressures. Rut depths were minimal and decreased with increasing slope classes due to reduced track slippage. Predicted erosion rates were high, primarily due to the extremely steep, long slopes and lack of adequate cover in some portions of the trail, illustrating the importance of proper erosion management practices on steep slopes.

Physical effects of hinges shape on chainsaw felling direction in Japanese Cypress

ABSTRACTIn Japan, most felling operations are performed manually with chainsaws, owing to the steep and difficult terrain involved. The average productivity per worker is approximately 5 m3 per day, and accident rates remain constant, with 57% of fatal accidents occurring during felling operations using chainsaws. These accidents were caused primarily by unpredictable felling direction, which typically results from unevenness of the hinge cut into the felling surface. The authors performed a pulling experiment using wires to clarify the physical function of the hinge during manual felling operations. They found that when the hinge was uneven, a moment was produced toward the thicker side of the hinge and increased as the hinge surface area increased. Consequently, a larger, uneven hinge shifts the actual felling direction away from the optimum direction.

Characteristics of Logging Businesses across Virginia’s Diverse Physiographic Regions

Logging businesses play an important role in implementing forest management plans and delivering the raw material needed by forest products mills. Understanding the characteristics of the logging workforce can help forest managers make better decisions related to harvesting operations. We surveyed logging business owners across Virginia’s three physiographic regions (Mountains, Piedmont, and Coastal Plain). Overall, logging businesses reported an average production rate of 761.37 t/business/week, but this varied substantially by region, with the highest production rates in the Coastal Plain (1403.55 t/business/week), followed by the Piedmont (824.69 t/business/week) and the Mountains (245.42 t/business/week). Many operations in the Mountains rely primarily on manual felling (66.6% of respondents) and these operations often have lower production rates. Across all regions, 81.7% of reported production came from operations that primarily utilized rubber-tired feller-bunchers for felling. Logging businesses were sorted based on reported production capacity and then divided into three groups (high, medium, and low production) based on total reported production. Across all regions, the majority of reported production was produced by the high production logging businesses. This was highest in the Piedmont, where the high production businesses accounted for 74.8% of total reported production.

How Climate Change Will Affect Forest Composition and Forest Operations in Baden-Württemberg—A GIS-Based Case Study Approach

In order to accommodate foreseen climate change in European forests, the following are recommended: (i) to increase the number of tree species and the structural diversity; (ii) to replace unsuitable species by native broadleaved tree species, and (iii) to apply close-to-nature silviculture. The state forest department of Baden-Württemberg (BW) currently follows the concept of Forest Development Types (FDTs). However, future climatic conditions will have an impact on these types of forest as well as timber harvesting operations. This Geographic Information System (GIS)-based analysis identified appropriate locations for main FDTs and timber harvesting and extraction methods through the use of species suitability maps, topography, and soil sensitivity data. Based on our findings, the most common FDT in the state forest of BW is expected to be coniferous-beech mixed forests with 29.0% of the total forest area, followed by beech-coniferous (20.5%) and beech-broadleaved (15.4%) mixed forests. Where access for fully mechanized systems is not possible, the main harvesting and extraction methods would be motor manual felling and cable yarding (29.1%). High proportions of large dimensioned trees will require timber extraction using forestry tractors, and these will need to be operated from tractor roads on sensitive soils (23.0%), and from skid trails on insensitive soils (18.4%).

Affective factors on residual tree damage during selection cutting and cable-skidder logging in the Caspian forests, Northern Iran

Although selection cutting has many advantages, its potential for damage to residual trees is a major challenge of forest management. The present study evaluated damage to residual trees during manual felling and cable-skidder logging operations in 18 instances of selection cutting in the Caspian forests of Iran. Data was collected from 100 m × 100 m systematic sample plots (0.1 ha) at each logging site. Harvest intensity ranged from 3.8 to 11 trees ha−1 and it averaged 7.3 trees ha−1. Damage to residual trees was 10.5–23.6% with an average of 16.9%. There was a positive and significant correlation between amount of damage and harvest intensity (R2 = 0.65, P < 0.01). The multiple regression analyses also indicated that there were statistically significant relation (R2 = 0.77, P < 0.01) between amounts of trees damage and independent variables (harvest intensity, ground slope and stand density). Injury to the bottoms of tree boles 100–200 cm2 in size was the most common types of damage. Damage was concentrated in small diameter trees (DBH < 40 cm). Most logging damage occurred during winching. Results suggest adherence to two silvicultural practices: (1) limit harvest intensity to 6 trees ha−1, (2) limit selection cutting in slopes, less than 50%. Additional operational suggestions are implementation of felling direction and avoid log extraction through dense stands.

Mechanized coppice harvesting with new small-scale feller-bunchers: Results from harvesting trials with newly manufactured felling heads in Italy

The revival of coppice management is being considered as one option to satisfy the increasing market demand for wood biomass. Commonly used harvesting systems in coppice forests (CF) are based on motor manual felling, but further mechanization of CF operations is desirable because of increasing labor costs and the high fatality rates associated with motor manual felling.The goal of this study was to determine the machine performance in terms of productivity, cost-effectiveness and cut quality of new feller-bunchers, when used on different types of CF. The study comprised of five tests on different sites in Italy, four of which represented a specific type of CF.Results showed that harvesting productivity varied from 3.1 to 8.6 dry t per scheduled machine hour (SMH) in multi-stem coppice stands (4.5–16 dry m3 SMH−1). Productivity reached 16.2 dry t SMH−1 in a short rotation forestry (SRF) control stand (39.4 dry m3 SMH−1) and it increased with stump mass. Recorded productivities tested in conventional CF were not as high as achieved in single-stem SRF, or in the mechanized felling of comparable softwood stands, but still matched the requirements of commercial mechanized logging. Costs varied between 3.57 and 20.56 € dry t−1 (1.47–14.17 € dry m3−1). Lowest costs were reached in the SRF stand and highest cost in the Mediterranean CF growing on moderate to steep terrain. Shear heads produced poor cuts and single-action shears performed worst. The disc saw produced very low cuts with low damage levels, which might be acceptable even under current cut quality specifications.

Productivity and cost of biomass harvesting for energy production in coppice natural stands of Quercus pyrenaica Willd. in central Spain

Biomass growing stocks, harvesting productivity and costs of energy production, were studied in thinnings of Quercus pyrenaica. Eleven forest sites were selected in coppices located in Castilla y León (Spain). Three systems were employed for harvesting: a mechanised whole tree harvesting (WTH) system, which included chipping at landing; a fully mechanised cut-to-length (CTL) harvesting system for firewood; and a semi-mechanised CTL system with manual felling and bunching. Three WTH trials had a hauling off 34.7–44.1 oven-dried tonnes (odt) ha−1. In contrast, only 11.6–30.0 odt ha−1 were obtained in the other eight CTL trials. Biomass weight equations for stems and whole trees were fitted. Worker operations were time-studied using software designed by the authors. The WTH system reached maximum productivity rates of 3.9 oven-dried tonnes per productive hour (odt h−1) for the felling and bunching operation and 6.9 odt h−1 for the forwarding operation. The mechanised CTL harvesting method achieved a productivity range of 1.3–0.5 odt h−1 for the harvesting operation. Furthermore, the average forwarding productivity was 7.3 odt h−1. Motor-manual felling and crosscutting in the CTL system accomplished a productivity range of 0.7–1.9 odt h−1. Manual bunching resulted in similar values. The lowest firewood unit cost for trees with 10 cm of diameter at breast height (DBH) was 62.0 € odt−1 using a semi-mechanised CTL system. Under similar conditions, this cost was 85.2 € odt−1 for the mechanised CTL system. Finally, the cost corresponding to chips at landing from WTH sites (average DBH = 10 cm) was 65.3 € odt−1.

Notice of Retraction: "Productivity and cost analysis of manual felling and skidding in Oriental spruce (Picea orientalis L.) forests" - Ann. For. Res. 55(2): 297-308, 2012

Notice of Retraction: "Productivity and cost analysis of manual felling and skidding in Oriental spruce (Picea orientalis L.) forests" - Ann. For. Res. 55(2): 297-308, 2012

Life cycle assessment of eucalyptus short rotation coppices for bioenergy production in southern France

AbstractShort rotation coppices (SRC) are considered prime candidates for biomass production, yielding good‐quality feedstock that is easy to harvest. Besides technical, social and economical aspects, environmental issues are important to be taken into account when developing SRC. Here, we evaluated the environmental impacts of delivering 1 GJ of heat from eucalyptus SRC using life cycle assessment (LCA), based on management scenarios involving different rotations lengths, fertilizer input rates, stem densities and harvest methods. Compared to equivalent fossil chains, all eucalyptus scenarios achieved savings of fossil energy and greenhouse gas (GHG) emissions in the 80–90% range, and had generally lower impacts, except for eutrophication. The 3 year rotation scenario was the most energy and GHG‐intensive, whereas manual felling for the longer rotations resulted in twofold larger photochemical ozone impacts compared to the other scenarios. Transportation of wood chips and fertilization were the top two contributors to the impacts, the latter being more important with the shorter rotation lengths due to the evergreen character of eucalyptus. The possibility of including ecosystem carbon dynamics was also investigated, by translating the temporary sequestration of atmospheric CO2 in the above and belowground biomass of eucalyptus as CO2 savings using various published equivalence factors. This offset the life cycle GHG emissions of heat provision from eucalyptus SRC by 70–400%.

Machinery-induced soil compaction in thinning two pine stands in central Italy

Thinning is a crucial practice in forest management. There is, however, a dearth of studies that focus on the effects of thinning carried out by modern heavy machinery on the physical properties of soil. We studied the consequences of thinning in two pine forests in Central Italy. The “full tree system” (FTS) to convert the whole biomass into chips was applied in both cases, in one case by manual felling in the other using a harvester. Different mass tractors were used to bunch and bring the trees to the landing. We investigated the behaviour of soil in terms of bulk density, total porosity, aggregate stability, penetration and shear resistances, which are good indicators of physical soil quality. Results show that thinning dramatically changed soil properties, depending on the method employed to fell trees and move them along the skid trails or on the whole logging area. In particular, the penetration resistance of soil increased by about 50% and shear resistance by almost 40%, hence confirming that care and surveillance are necessary during thinning to prevent reducing soil quality and, consequently, forest productivity.

Time consumption, productivity, and cost analysis of the motor manual tree felling and processing in the Hyrcanian Forest in Iran

An empirical time study was conducted to evaluate the performance of the current felling and tree processing methods used in Northern Iran’s Hyrcanian forest. Motor-manual felling is done mostly in winter, while tree processing starts when the felling season ends. We identified the elements of felling and processing work phases, and 142 cycles and 110 cycles were respectively recorded for felling and processing. On the basis of data analysis (time study), we developed statistical models of effective time consumption in the respective work phase and for its total productivity. The production rate of felling with and without delay time was 9.7 and 11.65 trees per hour (0.17 USD·m−3 and 0.21 USD·m−3), and the average production cost with and without delay was 1.21 USD and 1.45 USD per tree, respectively. The average productivity of processing was 35 m3 per effective hour and the average unit cost of processing was 0.22 USD·m−3.