Motor-manual Harvesting Research Articles

Influence of Chain Filing, Tree Species and Chain Type on Cross Cutting Efficiency and Health Risk

As one of the major parts of the chainsaw, the cutting chain has an important impact on productivity and health risk in motor-manual harvesting. The efficiency of cross cutting and quantity of sawdust produced in relation to different cutting chain settings, chain producers and wood species has been measured. The trial was set up to include two tree species (fir and beech) and saw chains from two different producers. The chains were filed at three different top plate filing angles and depth height gauges. All factors were significant in terms of cutting efficiency and wood dust production. The top plate angle recommended by producers proved to be the most efficient, with the smallest quantity of inhalable wood dust. Cutting chain settings can be adapted to the specific requirements of the user; however, safe working practices should be followed. Significant differences between chain producers mean that users should conduct rational decision making when choosing a saw chain.

Performance of Brush Cutters in Felling Operations of Willow Short Rotation Coppice

Short rotation coppice is an option for timely procuring biomass for use as a source of energy, but it often requires the use of expensive equipment. Small-scale farmers lack the ability to purchase such equipment, but rather can use their own affordable tools. Performance of motor-manual harvesting using brush cutters in a short rotation willow coppice was evaluated by coupling traditional, Global Positioning System (GPS), and Geographic Information System (GIS) tools and methods. Strong dependence relations were found between the time effectively spent to fell willow shoots and the row length. The delay-free time consumption accounted for 81% of the total observed time, while the time spent to fell the shoots accounted for 97% of the delay-free time. The net production rate was low (0.13 ha h-1) being related to the technology used. Delays (19%) affected the performance resulting in a gross production rate of 0.11 ha h-1. Nevertheless, small-scale farmers use this level of technology in harvesting their crops by adapting the crop rotation to very short cycles, possibly to cope with technical limitations of brush cutters. The plantation system, layout, and the weather conditions may act as performance-limiting drivers. Also, adequate planning of the operational layout has the potential to increase the field performance.

Harvesting and extraction impacts on Eucalyptus grandis × E. urophylla coppicing potential and rotation-end volume in Zululand, South Africa

From the early 2000s there has been a general shift in South Africa in harvesting and extraction systems from the use of semi- to fully-mechanised systems. Any increase in mechanisation, as is occurring in Zululand, will need to take into consideration damage to stumps and the subsequent ability to regenerate by coppice. In 2002, four types of harvesting and extraction systems, arranged in a randomised complete block design, were used to clearfell a stand of E. grandis × E. urophylla. A motor-manual harvesting system was used to carry out the manual harvesting system (Man). The fully mechanised system (Mech) consisted of a single-grip harvesting head used with a tracked excavator to carry out all felling and processing operations. Two additional systems (Man_Mech_3W and Man_Mech_Flexi) had increased levels of mechanisation over that of the Man treatment. Both these harvesting systems made use of a Bell debarker, with loading carried out by a Bell three-wheeled loader in the Man_Mech_3W, and by a Flexiloader in the Man_Mech_Flexi treatments. Data collected from these four treatments were used to determine the effects of mechanised harvesting systems on type and severity of stump damage, coppicing potential and coppice growth over the rotation. Irrespective of harvesting system, more damage occurred to the top than bottom half of the stump, with a significant decrease in coppice regrowth with increasing stump damage. Most damage and least coppice regrowth occurred in the extraction rows where the damage recorded could be attributed to vehicle movement, tear-outs and/or log stripping. There was no significant difference between the harvesting systems in terms of stump mortality, final stem stocking and rotation-end volume. Thus, individual components within each harvesting system can have a larger impact than the overall harvesting system used. Future research should focus on these components, and where associated damage occurs for a specific component, this should be lessened through management intervention, training or technological improvements.

Development of economic and environmental metrics for forest-based biomass harvesting

An assessment of the economic, energy consumption, and greenhouse gas (GHG) emission dimensions of forest-based biomass harvest stage in the state of Michigan, U.S. through gathering data from literature, database, and other relevant sources, was performed. The assessment differentiates harvesting systems (cut-to-length harvesting, whole tree harvesting, and motor-manual harvesting), harvest types (30%, 70%, and 100% cut) and forest types (hardwoods, softwoods, mixed hardwood/softwood, and softwood plantations) that characterize Michigan's logging industry. Machine rate methods were employed to determine unit harvesting cost. A life cycle inventory was applied to calculating energy demand and GHG emissions of different harvesting scenarios, considering energy and material inputs (diesel, machinery, etc.) and outputs (emissions) for each process (cutting, forwarding/skidding, etc.). A sensitivity analysis was performed for selected input variables for the harvesting operation in order to explore their relative importance. The results indicated that productivity had the largest impact on harvesting cost followed by machinery purchase price, yearly scheduled hours, and expected utilization. Productivity and fuel use, as well as fuel factors, are the most influential environmental impacts of harvesting operations.

Productivity and Cost-Effectiveness of Mechanized and Motor-Manual Harvesting of Grey Alder (Alnus incana (L.) Moench): A Case Study in Latvia

In Latvia, the management of grey alder stands is an important issue in non-state forests, where this species accounts for 14 % of the total non-state forest area. The motor-manual felling and processing of timber with a chainsaw is still a commonly used method in non-state forests, while timber harvesting in final felling is fully mechanized in state forests. This study examined the productivity and costs of the mechanized and motor-manual harvesting of grey alder following the cut-to-length CTL system and analysed factors influencing the productivity of harvesting of grey alder stands under Latvian conditions. Productivity rates achieved for mechanized and motor-manual harvesting were 7.04 and 2.99 m3 per productive work hour, respectively. Despite lower productivity, motor-manual harvesting was more cost-effective than mechanized harvesting. Improved working methods that could ensure higher production levels and increase the labour costs in the future have potential to increase the cost competiveness of the mechanized harvesting of alder stands in Latvia.

Mountain forest wood fuel supply chains: comparative studies between Norway and Italy

Case studies of mountain forest wood fuel supply chains from Norway and Italy are presented and compared. Results from previous studies in which greenhouse gas emissions and costs were evaluated using life cycle assessment and cost analysis respectively, are compared. The supply chain is more mechanized in Norway than Italy. Steeper terrain and low road density partly explain the persistence of motor-manual felling in the Italian case. Mechanized forest harvesting can increase productivity and reduce costs, but generates more greenhouse gas (GHG) emissions than motor-manual harvesting. In both cases, the main sources of GHG emissions are truck transportation and chipping. The total emissions are 22.9 kg CO2/m3s.o.b. (Norway) and 13.2 kg CO2/m3s.o.b. (Italy). The Norwegian case has higher costs than the Italian one, 64 €/m3s.o.b. and 41 €/m3s.o.b. respectively, for the overall supply chain. The study shows that mountain forests constitute an interesting source for fuel biomass in both areas, but are a rather costly source, particularly in Norway. The study also exemplifies the care needed in transferring LCA results between regions and countries, particularly where forest biomass is involved.

Berechnung von Mehraufwand und Minderertrag infolge des Trinkwasserschutzes im Wald

Calculation of additional expense and reduced revenue as a result of drinking water protection in the forest A good portion of the drinking water in Switzerland originates from groundwater wells in the forest. Within the framework of the Water Protection Ordinance these forest areas are designated as groundwater protection zones (core zone, S1; inner protection zone, S2; further protection zone, S3) to protect the drinking water supply against contamination. The designation of a forest area as a protection zone is connected to prescriptions and recommendations influencing forest management and causing additional costs for forest enterprises. On behalf of the Federal Office for Environment, an Excel tool has been developed. With this tool, the additional expense and reduced revenue can be calculated quickly and easily. To reflect the requirements in the tool, courses of action were defined, as they occur in forest management (e.g. no chemical wood treatment in the S2 and S3 zone, utilization of non-polluting fuels and lubricants). Subsequently, these courses were converted into mathematical formulae quantifying the additional costs. Three harvesting methods common in forest management were thereby distinguished, a motor-manual harvesting method, a fully mechanized harvesting method and a harvesting method for steep slopes. The results calculated with the drinking water protection tool can form an essential basis for the discussion on compensation payment for water services from forest management and provide a better communication between forest managers and water suppliers. However, the results of the tool are to be regarded rather as guidelines and should not be taken as absolutely.

Site impact after motor-manual and mechanised thinning in Mediterranean pine plantations

The study determined the site impacts of motor-manual and fully mechanised whole tree harvesting, as applied in the thinning of young pine plantations on the Tuscan coastline. The thinning was applied with selection criteria, removing between 36 and 39% of the tree number. The frequency of tree wounding was 1.5 and 5%, respectively for the mechanised and the motor-manual treatment. Wounds inflicted by the mechanised system were also four times smaller than those inflicted by the motor-manual system. The superior performance of the mechanised system was ascribed to its better capacity for handling cut trees. Soil bulk density increased by 3% and 6% after motor-manual and mechanised harvesting, respectively. The increase was small but significant, whereas the difference between treatments was not significant. Machine traffic resulted in a significant increase of CO2 concentration in the soil air, which was 0.4% in the undisturbed control plots and 0.8% in the machine tracks. No significant difference was found between the treatments. The CO2 concentration in the machine tracks was very near to the 1% critical threshold, beyond which biological activity is so constrained that soil recovery may be significantly delayed. When repeated entries are necessary, it is best to avoid creating new tracks by restricting traffic to designated permanent tracks. Properly applied mechanised harvesting does not cause heavier soil impacts than traditional motor-manual harvesting, but it results in a much lower stand damage. Foresters may support the introduction of mechanised harvesting, to the advantage of productivity, economics and work safety.

Comparison of harvester and motor-manual logging in intermediate cuttings of deciduous stands

Recently, new models of operational harvester heads that are suitable for work in deciduous forests and are able to process hooked trees or trees originated from stump shots have been designed. A mechanized harvesting method (harvester with head) is compared with conventional motor-manual harvesting methods in which a chain saw is used for felling, trimming, and crosscutting. Species composition of the sample stand was as follows: 58% aspen (Populus tremula), 19% lime (Tilia platyphyllos), 22% birch (Betula verrucosa), and 1% oak (Quercus robur). The study was completed under the aegis of the project of the 6th General Program of the EC. The labor efficiency was estimated using a time study method. Compared with common motor-manual harvesting, a UTC harvester with a CTL 40 HW head reduces the production time by about 70%. Depending on the number of timber assortments made per tree, operation of the harvester was from 1.7 to 3 times more efficient than chain saw operation.

A Method to Measure Saw-Chain Lubrication

A saw-bar with a saw-chain is a common tool in both mechanized and motor-manual harvesting operations. The friction between the saw-bar and the saw-chain must be reduced by lubrication. A precise oil flow control can reduce the amount of oil needed. Traditionally, mineral oils have been used, but the use of biodegradable vegetable-based oils has increased. The goal of this study was to evaluate the lubrication characteristics at different oil flows of two vegetable-based and one mineral-based saw-chain oil. The study was done on an experimental rig with a saw-chain speed of 23 m/s and with pressure between the saw-chain and a rotating rubber roller. The temperature of the saw-bar was used as an indicator of the lubrication efficiency. The saw-chain tension was constant and independent of temperature. In general, increased oil flow resulted in a lower temperature. For rapeseed oil and pine oils, the results were consistently significant between oil flows of 2 and 6 ml/min. At an oil flow of 2 ml/min and 5 minute test time, pine oil resulted in the highest temperature (121°C, standard deviation [SD] 6.4) and at 6 ml/min the lowest temperature (99°C, SD 1.1) compared with the other oils. No difference in temperature was found between mineral oil and rapeseed oils at oil flows of 2 or 6 ml/min. An oil flow of 2 ml/min was found to be enough to prevent high temperatures for all oil types. The study method, with an adjustable experimental rig as the tool, was found to be suitable for studies on lubrication of the saw-bar and saw-chain.

Log Damage and Value Loss Associated with Two Ground-Based Harvesting Systems in Central Appalachia

Log damage was examined in terms of volume and value losses by harvesting system, function, tree species, and log size in four central Appalachian hardwood sites. Observations were made of all grade logs during the felling, skidding, decking/sorting, and loading operations. Sawlogs sustaining damage to the bark or cambium were recorded with additional information obtained for the location, dimensions, and type of damage. The data were analyzed statistically to determine significant differences of damage and to estimate the potential damage probability of a log given select operational variables. The results suggest that motor-manual harvesting systems caused more damage to logs than mechanized harvesting systems. Felling resulted in significantly more log damage when compared to skidding, decking, and loading operations. Results also suggest that the process of skidding, decking, and loading of logs has very little impact on damage levels. Volume and value losses of damaged logs were not sensitive to tree species and log size.

Overseas developments in timber harvesting and transport and their relevance to Southern Africa

Synopsis The paper deals mainly with the developments of timber harvesting and transport systems in Scandinavia and Canada. Those developments are certainly relevant to Southern Africa. The shortwood method is used to over 90% in Sweden. A better word for the system is the assortment method since the wood can be cut in random lengths as well as standard. In Canada, on the other hand, 85% of the wood is being harvested by the treelength method. The development of the small powerful chainsaw made a great impact under the 1960's and motor manual harvesting is still a very competitive system provided the men are trained to use effective and labour-saving techniques. During the later part of the 1960's the processors for delimbing-slashing were introduced and there are today nearly 600 of those units in operation in Sweden. The felling phase is now the next to be mechanized. Most of the equipment is working in clear-cutting operations, however, the development of mechanized harvesting systems for thinning has ...