Manual Felling Research Articles

TIEMPOS Y RENDIMIENTOS DEL APROVECHAMIENTO FORESTAL EN EL SALTO, DURANGO, MÉXICO

Timber harvesting operations in four ejidos in the El Salto region of Durango, Mexico, were analyzed using a time and motion study to determine the operational productivity of manual felling, delimbing, bucking, skidding and mechanized loading. A total of 704 cycles for felling, 900 for mechanical skidding and 1,294 for mechanical loading were timed. The results indicate that the operational productivity in the manual felling cycle is 28.67 m3•h-1. Crane skidding was 19.83 m3•h-1 at an average distance of 43.13 m. Mechanized loading productivity was 35.27 m3•h-1. Productivity was shown to be sensitive to variations in the diameter and length of the trees and logs, as well as the distances found in the work cycles analyzed.

Potential for biofuel development in Tihvin and Boksitogorsk districts of the Leningrad region — The analysis of energy wood supply systems and costs

The existing and potential energy wood supply systems have been compared in terms of cost efficiency in Tihvin and Boksitogorsk districts of the Leningrad region to find optimal supply systems. In most cases the supply systems based on the cut-to-length method have the highest cost efficiency and provides costs of energy wood between 18.8 and 25.8 € m − 3 . For commercial thinnings the supply systems with manual felling are the most cost effective. In final fellings bigger average stem volume allows more productive use of harvesters that provides lower costs than systems with manual cutting. The total supply cost of energy wood from thinnings is higher compared to final fellings. Costs of energy wood cannot compete with the local price of coal and natural gas. However, energy wood is cheaper than heavy oil if transporting distances are shorter than 50 km. Main reasons for high supply costs of energy wood are low productivity of felling, hauling and transportation. Cost efficiency of energy wood supply can be improved through learning process and the use of modern machines.

Productivity and cost of manual felling with a chainsaw in Caspian forests

A field production study was conducted for a manual harvesting system using a chainsaw in a Caspian hardwood forest site. A selective cut was performed on a 42-hectare tract with an average slope of 30 percent. Felling time per tree was most affected by diameter at breast height and by the distance among harvested trees. The gross and net production rate was 20.6 m<sup>3</sup> and 26.1 m<sup>3</sup> per hour/one person, respectively. The unit cost considering the gross and net production rate was 1.05 USD/m<sup>3</sup> and 0.81 USD/m<sup>3</sup>, respectively. The significant variables included diameter at breast height (<I>D</I>) and distance among harvested trees (<I>L</I>) for the time expenditure model. This regression function is statistically significant at α = 0.01.

Условия труда на основных видах работ, выполняемых с помощью бензопил на лесозаготовках

Условия труда на основных видах работ, выполняемых с помощью бензопил на лесозаготовках

Production, Cost, and Soil Compaction Estimates for Two Western Juniper Extraction Systems

Abstract Harvesting trials were performed during the winter and spring of 2003–2004 in central Oregon to compare the costs, production rates, and soil compaction impacts of two systems for harvesting western juniper (Juniperus occidentalis). The two systems compared were a conventional system consisting of manual felling, delimbing, and bucking using a chainsaw and skidding logs with a rubber-tired grapple skidder and a mechanical system that used a feller-buncher, a rubber-tired grapple skidder to skid whole trees, and a stroke-boom delimber. Stump to deck harvesting costs ranged from $32.15 to $49.48/ton for the conventional system and from $60.07 to $63.11/ton for the mechanical system. A limited trial was conducted with the mechanical system that merchandized fence posts as well as sawlogs. When fence posts were produced also, stump to deck costs were reduced to $31.56/ton. Soil compaction was measured pre- and postharvest using a soil penetrometer. Paired t-tests showed a statistically significant difference between harvested sites and nonharvested sites at depths of 2 and 4 in. (P = 0.032 and 0.001, respectively) but no difference between harvest systems. West. J. Appl. For. 21(4):185–194.

Improvements in Value Recovery through Low Stump Heights: Mechanized versus Manual Felling

Abstract Stump heights were measured on two blocks harvested during the summer of 2000 in north-central British Columbia. Each block was of similar stand and terrain characteristics, consisting mainly of subalpine fir (Abies lasiocarpa) with minor components of white spruce (Picea glauca × P. engelmannii) on gentle slopes. The blocks were harvested by two different contractors using different felling methods: mechanized felling with a feller-buncher and manual felling with a chainsaw. The average measured stump height from mechanized felling was 8.8 cm lower than that of manual felling, measuring 21.9 and 13.1 cm, respectively. When the saw kerf of felling equipment and stump-pull were included, the average stump height of mechanized felling was shown to be 5.8 cm (17%) lower than manual felling. High-end and low-end potential value losses were determined based on average sawlog values (Canadian [CN] $60/m 3 ) and pulp log values (CN$40/m 3 ), respectively. The potential value loss from manual felling was estimated to be up to CN$0.33/tree more than from mechanized felling. This result indicated that mechanized felling recovered up to CN$160/ha over manual felling when an average sawlog value and the stand density information from the study site were used in the calculation. The study demonstrated that lower stump heights than the 30 cm maximum stump height set by the Forest Practices Code of British Columbia are attainable with both felling methods. Sensitivity analysis was performed to determine the potential value and volume gains for a range of stump heights from 0 to 30 cm. Operational constraints were identified in the study, and recommendations for minimizing stump heights are presented.

Effect of Ground Slope, Stump Diameter, and Species on Stump Height for Feller-Buncher and Chainsaw Felling

Stump heights were measured on six clear-cut blocks in the central interior of British Columbia using a systematic sampling method. Felling method, ground slope, species and stump diameter were analyzed to determine their effect on stump height. Mechanized felling with a feller-buncher resulted in lower stumps by 5.5 cm on average than those from manual felling with a chainsaw. The wide range (9.6 cm to 23.4 cm) of the average stump heights sampled from six clear-cut units indicates that other factors such as slope, species and stump diameter may influence stump height. When considering tree species, the feller-buncher left lower stump heights for subalpine fir and white spruce, while chainsaw felling resulted in lower stumps for Douglas-fir. Average stump and feller-buncher stump heights tended to increase as percent slope increased up to 45%, but the opposite trend was found in chainsaw felled sites with slopes greater than 45%. Both feller-buncher and chainsaw felling methods resulted in lower stumps as the average stump diameter increased. On ground slopes less than 30% and stump diameters between 30 and 70 cm, our analysis suggested that feller-buncher felling resulted in lower stump heights than chainsaw felling. Chainsaw felling can cause stump-pulls, slabs, and unevenness at the bottom of the tree being felled, requiring a further reduction of wood that could potentially be used for solid wood products. Feller-buncher felling, however, results in greater wood volume waste as the result of a thicker saw blade kerf than does chainsaw felling.

Damage to Appalachian Hardwoods from Diameter-Limit Harvesting and Shelterwood Establishment Cutting

Abstract Residual stand damage was assessed in 10 ac stands harvested with either a 12 in. diameter-limit harvest, a 16 in. diameter-limit harvest or an establishment cut of the shelterwood method. Each stand was logged using manual felling and cable skidding; treatments were replicated four times. The 12 in. diameter-limit harvests had the lowest residual basal areas but residual stems had the highest percentage of damage and largest stem wounds. In all three treatments, as tree size (dbh) increased and distance to skid trail increased, the probability of individual tree damage decreased.

A Comparison of Felling Techniques on Stump Height and Log Damage with Economic Interpretations

Abstract This study investigated two of the many potential sources of value loss that occur during logging operations: stump heights and butt log damage. The potential value loss was determined for manual felling and five different felling heads for logging sites located in the central north island of New Zealand. Manual felling produced the highest stumps and three different felling heads (Hultdin, Timbco, and Warratah) produced second highest stumps. The group with the lowest stumps was felled with AFM Magnum and Koehring felling heads. The Warratah felling head had the lowest incidence of butt log damage, while manual felling had the highest proportion of damaged butt logs. The majority of the damage to the butt logs was slabbing damage; all felling techniques produced little stump pull damage. A comparison of the potential value loss showed that the Koehring produced the lowest potential value loss at US$128/ac, while manual felling had the highest potential value loss at over US$420/ac. West. J. Appl. For. 15(2):59-61.

A Comparison of Skyline Harvesting Costs for Alternative Commercial Thinning Prescriptions

Abstract Harvesting production and costs were examined for three alternative silvicultural prescriptions at two sites in the Coast Range of Oregon. Thirty-three-year-old Douglas fir stands were commercially thinned to residual densities of 247, 148, and 74 trees per hectare (tph) [100, 60, and 30 trees per acre (tpa), respectively]. Detailed time studies were conducted on manual felling and uphill skyline yarding with small yarders. Separate regression equations were developed to predict delay-free felling cycle time and delay-free yarding cycle time. The 74 tph [30 tpa] treatment had the highest production rate and was the least costly to harvest. Total harvesting costs of the other two treatments averaged from 6.0% (148 tph [60 tpa]) to 12.3% (247 tph [100 tpa]) more than the 74 tph [30 tpa] treatment.

A Comparison of Logging Planning, Felling, and Skyline Yarding Costs Between Clearcutting and Five Group-Selection Harvesting Methods

Abstract Logging planning, felling, and cable yarding costs were determined for five group-selection treatments and a clearcut in a 90 yr old Douglas-fir (Pseudotsuga menziesii) stand in western Oregon. The harvesting system included manual felling and a yarder rigged in a standing skyline configuration with a mechanical slackpulling carriage. The clearcut treatment had the lowest total harvest cost; costs of the group-selection treatments were 7.3 to 31.5% higher than the clearcut. Yarding cost associated with road and landing changes, plus the cost of equipment moving, set up, and tear down allocated over different treatment volumes removed had the biggest influence on total cost for each silvicultural treatment. West. J. Appl. For. 11(3):90-96.

Évolution quinquennale de la régénération protégée lors de récoltes par abattage manuel dans des sapinières

In 1985, an experiment was undertaken in the Gaspé peninsula, in Québec, in different stand types to assess the feasibility of preserving advance growth by changing logging methods. This article deals with manual felling combined with wheeled cable skidders in balsam fir stands. Regeneration was assessed before, immediately after, and 3 and 5 years after logging in five 2-ha pairs of blocks, in order to compare the effect of traditional harvesting (control) and a method using directional felling and spaced skidding trails (preserved).The use of directional felling and spaced skidding trails resulted in a decreased loss of advance growth. Five years after logging, this loss in softwood stocking for the preserved blocks was still lower in each of the five pairs; the difference averaged 25%. Moreover, the regeneration height in the preserved blocks was slightly greater, which seems to indicate a lower level of invasion by brush and herbaceous vegetation after logging as a result of this method.

Amount and Characteristics of Logging Residue on Harvested Areas in Vermont

Abstract An assessment of the type and volume of logging residue was completed for 49 harvested areas in Vermont (manual felling, ground skidding). The line intersect technique was used to sample residue in the areas. On a per-acre basis, the mean volume of logging residue was 264 ft3 with a range of 69 to 797 ft3. The average volume of residue found in a soft-wood stand was 169 ft3 with a range of 69 to 313 ft3. The average volume of residue found in a hardwood stand was 329 ft3 with a range of 69 to 797 ft3. The average piece size was 3.4 in in diameter at the small end, 6.1 in at the large end, with a length of 16.3 ft and volume of 1.6 ft3. North. J. Appl. For. 3:63-65, June 1986.

Analytical Solutions of Special Queuing Situations in Logging

Three cases in logging can be considered as queuing situations: the operation of (1) the felling and processing devices of a tree harvester, (2) the pick-up and processing devices of a processor, and (3) manual felling machine skidding. These cases can be represented by a queuing model with a special characteristic — queue length equals zero or one. Analytical solutions of this model that involve deriving the means, variances, and probability density functions of waiting times and idle times are developed.