Replacing Steel Cable with Synthetic Rope to Reduce Operator Workload During Log Winching Operations

The authors conducted three comparative tests, to determine if the replacement of steel cable with synthetic rope may allow reducing the physiological workload of forest operators assigned to log winching tasks. The tests were conducted in Northern Italy, on the Alpine mountain and involved 7 volunteer subjects. The physiological workload was determined by measuring the operator’s heart rate upon completion of every task, using heart-rate monitors. Test one was conducted under simplified, controlled conditions and detected a statistically significant reduction of relative heart rate when carrying synthetic rope, as compared to steel cable. However, tests two and three were performed under real operational conditions, and were inconclusive. Real operational conditions are characterized by the interaction of many factors, which may confound the results of the tests, or offset the benefits potentially obtained with the introduction of synthetic rope. Nevertheless, the introduction of synthetic rope offers the benefit of easier handling, which was very much appreciated by all test subjects.     

Modelling and comparing timber winching performance in windthrow and uniform selective cuttings for two Romanian skidders

Cable skidders are one of the most used means for logging. In overall skidding operations, winching operations mark themselves out by consuming an important amount of time, which, depending on the work conditions can reach up to 43 % of the total skidding time. A better understanding of those conditions that may act as significant influence factors when estimating time consumption is needed as a prerequisite for better work organization. Based on an extensive time study, this paper demonstrates that along with influence factors that were already identified as being significant (especially winching distance), other influence factors, such as log volume, work pattern, felling area conditions and intervention type, slope, and winching direction, may prove significant in predicting time consumption for the main work elements of winching operations, as well as for a winching cycle. All the variables mentioned presented a great significance (p < 0.05) for a winching replication, and taken apart, they presented great significances for certain work elements. Distance was the most significant independent variable for all the realized time prediction models, slope and winching direction became relevant especially in the case of manual pulling of the cable, whereas intervention type and work patterns made the difference when performances were evaluated. The amount of data within data pools may have a great importance when trying to emphasize the relevance of different variables, as demonstrated by this paper.     

Wood Extraction with Farm Tractor and Sulky: Estimating Productivity, Cost and Energy Consumption

A winch and a sulky can transform a farm tractor into an effective small-scale logging machine, closely resembling a wheeled cable skidder. The additional cost of these implements is very small, but they offer significant benefits when extracting timber under the conditions of small-scale forestry. The authors developed a productivity model for skidding timber with wheeled farm tractors, equipped with winch and sulky. The origin data pool contained over 300 individual skidding cycles, extracted from 8 separate tests. Statistical analysis of the data allowed calculating a simple mathematical relationship for estimating skidding productivity as a function of significant work conditions, such as: piece size, winching distance, tractor power, skidding distance and crew size. This model can provide useful directions to prospective users, contributing to operation planning, costing and optimization. It can predict a large proportion of the variability in the data and was successfully validated using reserved cycle records, extracted from the same data pool and not used for model development. Depending on tractor power and piece size, the average turn volume and productivity can exceed respectively 2 m³ per cycle and 4 m³ per Scheduled Machine Hour (SMH). Top performance can reach 8 m³ SMH⁻¹, with heavy tractors and large logs.     

Operational impacts to residual stands following ground-based skidding in Hyrcanian Forest, northern Iran

Hyrcanian (Caspian) Forest in northern Iran has a richness of biological diversity, with endemic and endangered species. The usage of ground-based skidding is well accepted practice for the extraction of timber from the forest, but this operation has tended to cause the greatest environmental problems. The aims of the study were to evaluate and comparison of operational impacts, residual stand damage, regeneration, and to quantify these effects such as: the extent of the damage, wounding patterns, size and distribution after logging operations that utilized two different methods: short-log and long-log. A Timberjack cable skidder was used and the study location was in the Kheyrud Forest. Post harvesting assessment of damage to the residual stand was compared along skid trail by 100% inventory method and also for the assessment of regeneration damage along winching strips. The results show that along winching strips the percentage of damage to the regeneration was 44% and 36%, while the tree damages along skid trails reached 2.3% and 4.1% in the short-log and long-log methods, respectively. The greatest average amount of damage to a bole occurred along the first 1 m up from the ground (97%) and also within 4 m of the skidder centerline (80%). These results show that the short-log method causes less damage to the residual stand than the long-log method. Tree location to skidder trail appears to have a significant effect on the number and height of scars on a tree. Well designed and constructed trails should be wide enough to allow wood extraction from the forest. Damage to the residual stand might be reduced by proper planning and training of logging crews.     

Time Prediction Models and Cost Evaluation of Cut-To-Length (CTL) Harvesting Method in a Mountainous Forest

Time equations are derived for felling with chainsaw, skidding with cable wheeled skidder, loading with grapple hydraulic loader and trucking of logs within a cut-to-length harvesting method. The continuous time study method was applied to collect data for felling, skidding, loading and a transportation model. Multiple regression analysis via SPSS software was applied to develop the time models. Felling time was found to be highly dependent on diameter at breast height. Skidding distance, winching distance, slope of the trail and piece volume were significant variables for the skidding time prediction model. The loading time model was developed considering piece volume. Transportation distance and load volume were used as independent variables in modeling the transportation time. The net production of felling was estimated at 12 trees/h (56.65 m³/h). The net production rates for skidding, loading and traveling averaged 18.51, 41.90 and 3.32 m³/h respectively. The total cost of harvesting from stand to mill was estimated 19.70 €/m³. The skidding phase was the most expensive component of the cut-to-length method. The bucking and delimbing components were less costly than the other logging phases. The results of this study can be used for harvesting planning and productivity optimization.     

利用轮式小拖拉机进行集材的研究

将轮式小拖拉机进行改造,装配绞盘机和搭载板后进行集材,在集材距离200~300 m时,日集材量为:冬季20~30 m3,夏季15~20 m3,比畜力集材提高了4~6倍;集材成本为15~20元.m-3,是畜力集材的50%。利用轮式小拖拉机进行集材,对地表及幼苗幼树的破坏程度大幅度降低,是目前可供选择的一种较好的集材方式。     

人工林集材绞盘机分析与评价

阐述绞盘机在各种工程索道中的应用 ,用价值工程分析方法筛选几种适宜人工林集材绞盘机 ,并预测林业和公路桥梁、水电等土建工程无支架施工绞盘机的发展前景     

无卷筒离合器的轻型绞盘机设计

为适应我国山地丘陵多、坡度陡和绞盘机作业强度大、维护不便等特点,提升绞盘机的操作性和转运能力,设计了一种无卷筒离合器的轻型绞盘机,阐述了绞盘机总体布置方案和工作原理,设计了采用齿轮传动的新型选筒机构,取代传统绞盘机的卷筒离合器,传动可靠,制造工艺简单,对选筒机构的花键轴和齿轮进行了强度校核,并对绞盘机传动系统的主要零部件进行了选型与设计,利用Matlab对绞盘机卷筒进行了轻量化优化设计,利用Solidworks进行了卷筒三维建模和有限元分析。结果表明,优化后的卷筒强度满足要求。该绞盘机采用新型的选筒机构,结构紧凑,安全可靠,整机轻量化程度高,便于运输,操作简便,可以有效提升绞盘机的工作效率。     

JSX3-1.5绞盘机性能分析及改进设计

ＪＳＸ３－１．５绞盘具有轻型化、适宜性强、通用性好、高效率、低能耗等特点，是目前国内实用的一种木材生产机械。在使用情况调查的基础上对该机性能进行分析，对存在问题提出改进意见。     

当前伐区工程设计与准备作业施工中的几个问题

本文就伐区工程设计与准备作业施工中装车场位置选择、装车缆索设备的架设、简易运材道路的修建等问题进行了深入细致的研究，总结出了不同情况下的最佳方案。     

多功能轮式集材拖拉机搭载板装置的设计研究

通过对我国集材拖拉机发展沿革及目前林业生产作业条件分析,研发一种新型多功能集材拖拉机对目前林业生产具有重要意义.集材装置是集材拖拉机最具有特点的主要工作装置,本文对多功能轮式集材拖拉机集材装置（搭载板装置）整体结构进行设计.首先根据集材拖拉机趟载量要求确定搭载板整体结构尺寸,宽度为1 050 mm,长度为1 219 mm,厚度为20 mm.其次对搭载板辅助结构进行设计计算,使用Solid Works三维绘图软件建立搭载板的3D模型.最后基于有限元校核搭载板的强度,得到搭载板在最大压力载荷下的位移云图和应力云图,结果表明所设计的搭载板满足强度要求.     

以手扶拖拉机为主机的JS3-2绞盘机研制

论述手扶拖拉机改制绞盘机的技术关键,对绞盘机进行总体动力学分析,提出真实反映绞盘机功率的计算法,即按最不利工作条件计算起重提升功率和重车上行功率,择其大者并有一定过载能力的计算方法,以此作为JS3-2绞盘机主机——手扶拖拉机选型的依据。介绍JS3-2绞盘机整机构造、工作原理及其主要技术参数,并进行性能分析,阐述其在生产中的应用。实践证明:JS3-2绞盘机具有合理的功率匹配、优越的性能、人性化的操作,在木材采运、路桥和水利电力工程等领域得到广泛应用。     

Effect of removal of logging residue on nutrient leaching and nutrient pools in the soil after clearcutting in a Norway spruce stand

Following clearcutting applying the conventional stem-only harvesting method in a Norway spruce (Picea abies (L.) Karst.) stand and different levels of removal of logging residue, the nutrient fluxes from the heaps of logging residue and from the O horizon were monitored over four growing seasons and the soil nutrient pools were determined. Three levels of removal of logging residue were carried out using (i) conventional stem-only harvesting (no residues removed); (ii) residues removed; and (iii) removal of branches (foliage left on site). The heaps of logging residue were a minor source of inorganic N entering the soil in the water percolating through the heaps, but they were a significant source of organic N, P, Ca, Mg, and especially K. Nutrient fluxes from the O horizon were in general greater under the heaps of logging residue as compared to soils without overlying logging residue. The leaching of inorganic N from the O horizon under the heaps of logging residue resulted in a net loss of these compounds, while the O horizon without overlying logging residue gained N. The removal of logging residue significantly decreased the extractable K pools in the soil while it or conversely, the presence of residue heaps had no significant effect on the pools of organic matter and the pools of N, P, Ca, and Mg in the O horizon and in the 0–10 cm soil layer. The results show that the short-term effects of logging residue on nutrient dynamics in the soil can be complex and difficult to interpret in terms of site productivity as there are changes in the nutrient fluxes, which imply the opposite effects on site productivity. However, the results do indicate that, in the short-term, the removal of logging residue does not impair pools of N in the soil nor site productivity on sites where the availability of N limits productivity.     

Effects of aggregating forests, establishing forest road networks, and mechanization on operational efficiency and costs in a mountainous region in Japan

We investigated forest road networks and forestry operations before and after mechanization on aggregated forestry operation sites. We developed equations to estimate densities of road networks with av...     

可移动装配式林业索道支架受力分析

支架是集材索道系统的重要组件,用以承托钢索,保证索道有足够的净空高度。但传统的南方人工林集材作业中多数采用活立木作为索道支架,活立木受其生长位置限制,难以保证最优集材路线,不适应现代小规模木材采集需求,为解决人工林索道集材中难以寻找合适的活立木作支架问题,研究设计出一种分段组合加绷索固定的可移动装配式钢管支架。通过力学和仿真分析,对承索方式、不同分段比例及绷索固定位置进行了优化。当分段位置于杆件的0.59L处时,效果最好,抗压能力是没有分段时的1.7倍。支架采用索鞍托索,使支架受力由传统的以承受弯矩为主变成以承受压力为主,改善了支架的受力条件。同时支架中间设置绷索固定后,增加了支架的约束条件,减小了支架的柔度,支架的临界载荷比无绷索固定的支架提高3倍以上。支架设计成分段可拆,降低了单个支架部件的重量,单个部件最大不超过50kg,便于在林区转移安装;支架采用标准镀锌管制造,取材方便,成本低廉,有利于降低索道系统成本。经试验及生产验证,可移动装配式林业索道支架转移、架设方便,使用安全可靠,特别适合山地林区择伐与小规模皆伐集材需要,对在人工林集材作业中推广小型索道集材,减小集材作业对生态环境的影响具有重要的意义。     

Changes in physical properties of a soil associated with logging of Eucalyptus regnan forest in southeastern Australia

Logging operations can cause soil profile disturbance and compaction. Soil profile disturbance and compaction change soil physical properties, which may reduce site productivity, increase soil erosion and degrade catchment water quality. This study was undertaken to measure the effect of logging on physical properties of the 0–100 mm surface soil in the Victorian Central Highlands, southeastern Australia. Soil physical properties were measured in the snig tracks, log landings, general logging areas (disturbed areas which were not occupied by snig tracks or log landings) and undisturbed areas. Within the general logging areas, measurements were made for three levels of soil profile disturbance: litter disturbed, topsoil disturbed and subsoil disturbed.

The results indicated that logging significantly increased bulk density and decreased organic carbon and organic matter content, total porosity and macroporosity on over 72% of the coupe area. However, on 35% of the coupe area, the snig tracks, log landings and subsoil disturbed areas of the general logging area, bulk densities and macroporosities reached critical levels where tree growth could be affected. On these areas, organic carbon decreased between 27 and 66%, bulk density increased between 39 and 65% and macroporosity decreased between 58 and 88%.

Saturated hydraulic conductivities decreased to critical levels for runoff to occur on over 72% of the coupe area (topsoil and subsoil disturbed areas of the general logging area, snig tracks and log landings). On this area, the reduction in saturated hydraulic conductivity varied between 60 and 95%.     

森林采运作业过程碳排放分析

合理的森林采伐能开发利用森林资源,促进林木生长,但盲目采伐会导致生态环境的破坏。以生命周期评价法的B2B（business-to-business）模式为基础,采用过程分析法,核算森林采运过程各阶段的温室气体排放量。结果表明：采运过程中产生的碳排放约为7.530 6~11.659 8 kg/m3,约占其固碳能力的2.2%~5.7%;燃油消耗是最主要的碳排放源,CO2是其排放的最主要温室气体,碳排放量与集运材距离呈正相关;采伐段碳排放最少,仅0.573 6 kg/m3,索道集材、拖拉机集材排放分别是采伐段的1.04、1.72倍,运材段产生的排放量最多,当运材距离为40 km时,汽车运材和农用车运材排放量分别是采伐段的11.1和17.6倍;油锯采伐＋索道集材＋汽车运材为最优作业模式。研究结果可为森工作业的减排提供理论参考。     

Root anchorage of hinoki <Emphasis Type="Italic">(Chamaecyparis obtuse</Emphasis> (Sieb. Et Zucc.) Endl.) under the combined loading of wind and rapidly supplied water on soil: analyses based on tree-pulling experiments

Wind damage in Japan is mainly caused by typhoons (i.e., tropical cyclones), which are characterized by intensive heavy rainfall and strong winds. In this study, we conducted tree-pulling experiments on two sites to find out whether rapidly supplied water on the soil would affect stability of root anchorage of hinoki (Chamaecyparis obtuse (Sieb. Et Zucc.) Endl.), as expected. For the experiments, we first supplied several quantities of water around the target trees, and then they were pulled down using a wire winch. On study site 1 (Kamiatago experimental forest), we applied general tree-pulling experiments (no water supply) in 2008 and six different irrigation treatments around the target trees in 2009. On study site 2 (Chiyoda experimental forest), we applied one irrigation treatment in 2009. As a result, five trees were uprooted and two were broken in 2008, and all nine trees were uprooted in 2009 on study site 1, regardless of irrigation treatment. On study site 2, two trees pulled down after 4 h of water supply were ruptured at the stem base, opposite to two trees pulled down immediately after supplying water. The water content below the root plate significantly affected root anchorage and more specifically, the maximum turning moment, stem angle at the maximum force, and stiffness index. Moreover, water inside the root plate increased root anchorage at the beginning of a tree failure process. However, it also reduced the root plate area of the hinge side. Conversely, high water content below the root plate decreased root anchorage.     

Time consumption, productivity, and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions.An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning.Based on the identified elements of skidding work phase and 130 recorded cycles,we calculated the models for effective time consumption,total productivity,and unit cost.The validity of the model was tested at 95% confidence interval.The average load volume per cycle was 2.82 m 3,average one way skidding distance was 450 m,and the average slope was 18%.The average travel speed of unloaded skidder was 5.8 km·h-1,and the average speed of loaded skidder was 0.1 km·h-1 higher than the speed of the unloaded ones.The travel speed was predominantly affected by longitudinal slopes and types of strip roads.The average speed of pulling the cable was 1.16 km·h-1,and that of load winching was 0.74 km·h-1.The average outputs in skidding was 10.6 m 3 ·h-1 and the unit cost was 12.1 US$ per hour.The time consumption and productivity of skidding depends on distances and slope,number of logs per cycle,volume,log length,etc.However,the influence of variables is not the same.