Sang-Kyun Han

Soil compaction associated with cut-to-length and whole-tree harvesting of a coniferous forest

The degree and extent of soil compaction, which may reduce productivity of forest soils, is believed to vary by the type of harvesting system, and a field-based study was conducted to compare soil compaction from cut-to-length (CTL) and whole-tree (WT) harvesting operations. The CTL harvesting system used less area to transport logs to the land- ings than did the WT harvesting system (19%-20% vs. 24%-25%). At high soil moisture levels (25%-30%), both CTL and WT harvestings caused a significant increase of soil resistance to penetration (SRP) and bulk density (BD) in the track compared with the undisturbed area (p < 0.05). In the center of trails, however, only WT harvesting resulted in a signifi- cant increase of SRP and BD compared with the undisturbed area (p < 0.05). Slash covered 69% of the forwarding trail area in the CTL harvesting units; 37% was covered by heavy slash (40 kgm -2 ) while 32% was covered by light slash (7.3 kgm -2 ). Heavy slash was more effective in reducing soil compaction in the CTL units (p < 0.05). Prediction models were developed that can be used to estimate percent increases in SRP and BD over undisturbed areas for both CTL and WT harvesting systems.

Effects of slash, machine passes, and soil moisture on penetration resistance in a cut-to-length harvesting

Abstract Multiple entries into forest stands are often needed for fire hazard reduction and ecosystem restoration treatments in the Inland-Northwest U.S.A. region. However, soil compaction occurring from mechanized harvesting operations often remains for many years and may contribute to a decline in long-term site productivity. A controlled experiment on a silt loam soil was conducted to determine (a) the effectiveness of logging slash to buffer compaction, (b) the influence of the number of machine passes, and (c) the contribution of soil moisture to changes in penetration resistance during a cut-to-length harvest in northern Idaho. Penetration resistance was measured at three soil depths (10, 20, and 30 cm) for three different moisture contents (low, medium, and high) and slash amounts (none, light, and heavy) after each of 12 machine passes (one pass each with a harvester and an empty forwarder, and 10 passes with a fully-loaded forwarder). At all three soil depths the main effect of moisture content and machine passes on penetration resistance was significant, but slash amounts alone did not significantly affect penetration resistance. After 12 passes, we measured the greatest penetration resistance in the medium soil moisture treatment at 5 to15 cm of soil depth. When evaluated at similar moisture contents after harvesting, the soil that was driest during machine traffic (low moisture treatment) had the lowest penetration resistance. Slash was important for protecting the soil against compaction in the medium and high soil moisture treatments. Penetration resistance did not significantly increase after the second pass of a fully-loaded forwarder (31,752 kg) at any moisture content or slash level. Managing felling operations to take advantage of dry soil conditions or using slash when soils are moist may help reduce ruts and avoid long-term compaction impacts on this soil type.

Evaluating the System Logistics of a Centralized Biomass Recovery Operation in Northern California

Abstract In this study, we evaluated the productivity and cost of each component in a unique centralized biomass recovery operation to determine cost-effective system logistics. The system was divi...

Effects of grate size on grinding productivity, fuel consumption, and particle size distribution.

Abstract Matching the right feedstock quality to a biomass conversion technology effectively facilitates the energy conversion process and improves the economic feasibility of forest biomass for en...

Harvesting Cost and Productive of Tree-Length Thinning in a Pinus densiflora Stand Using the Tower Yarder (HAM300)

Abstract Logging equipment and method have a major influence on harvesting productivity and cost. This study investigated the productivity and operational costs of tree-length cable yarding system using HAM300, a domestically developed tower yarder. We tested HAM300 for thinning operation in Pinus densiflora stands at Gangreung, Gangwon-do on April, 2014. To assess the productivity we conducted time study for each stage of the operation. When the average time/cycle was examined for each stage of the operation, the longest was for yarding (241 sec), followed by delimbing (237 sec), felling (153 sec), and processing (103 sec). Furthermore, productivity for felling was 8.6 m 3 /hr, followed by delimbing (5.1 m 3 /hr), yarding (3.5 m 3 /hr), and processing (8.1 m 3 /hr). The total cost for the tree-length logging system was 58,446 won/m 3 , of which the majority was incurred by the yarding cost at 46,217 won/m 3 (79.3%), whereas the lowest cost was for felling at 2,359 won/m 3 (4.1%). We suggest that it is necessary to foster specialized operators and provide training in operating the tower yarder thereby implementing efficient harvesting system resulting from low-cost yarding.Key Words: cable logging, harvesting cost, tower yarder, tree-length logging

Trucking Productivity and Costing Model for Transportation of Recovered Wood Waste in Oregon

The use of woody biomass has received considerable attention for energy production. However, high production and transportation costs can be a barrier to woody biomass use in some regions. Developing cost-effective transportation systems has become an economically critical issue to expand biomass use. We developed a computer model, named BIOTRANS, to estimate biomass transportation productivity and cost in western Oregon. We used BIOTRANS to evaluate the effects on transportation costs of six different truck configurations, four transported material types, and over 100 travel routes. Different truck configurations, transported material types, and travel route characteristics were found to significantly affect transportation costs. A four-axle truck and single trailer was the most cost-efficient hauling configuration for the conditions studied, and shavings had 30 percent higher trucking costs than other hog fuel, chips, and sawdust.

A Study on the Assessment of Standard Wage System for Forestry Workers in Korea

Working in the forest would require a wide range of skills and experience for specific tasks which involve with a high level of risks to workers safety. However, there has been a concern on the current standard wage system for forest workers because it does not effectively reflect the characteristics of typical working conditions in the forest. In addition, the current standard wages for forestry workers was estimated based on the construction industrys wage system. Therefore, the purpose of this study is to assess a current wage system through the mail survey method and to develop a new wage system for forest worker which effectively reflects skill sets and experience required for successful completion of the work in the forest. We mailed the survey questionnaire consisting of 19 questions to 659 forest workers and received 188 responses resulting in a 28.5% response rate. The results showed that the current average optimal wages of forest worker, special worker and feller were 97,680won/day, 127,559won/day and 152,403won/day, respectively though there were variations depending on the regions. In developing the new standard wage system, this study suggest the current work types(worker, special worker and feller) could be divided into 5 work types (forest-environment workers, forest operations in beginner, forest operations in intermediate, forest operations in advanced and forest equipment operator) reflecting specialty of forest operation thereby stabilizing the new wage system for forest workers.