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.     

吉林柳树河林场集材道植被更新研究

通过对吉林柳树河林场的集材主道、叉道的植被天然更新的调查及分析,结果表明:1)集材主道的更新树种以喜光树种香杨、柳和白桦为主,其中香杨是更新最早的树种;叉道以核桃楸和水曲柳为主。2)从更新株数、主要更新树种平均高、平均年龄及植被平均盖度上看,集材叉道西坡更新状况最好,集材主道次之,集材叉道东坡最差。     

南方集体林区集材生产优化选择分析研究

应用马秋思理论和数理统计方法综合分析木材生产中较为普遍采用的 3种典型集运材方式的成本K与集材距离L的关系 ,并给出集材生产优化选择计算实例。     

亚布力林业局适宜集材方式的探讨

本文根据几种集材方式的特点,结合亚布力林区的实际情况,对目前亚布力林业局适宜的集材方式进行了探讨。通过比较论证,认为畜力原木集材是目前亚布力林区适宜的集材方式。今后集材方式的改革应是机畜结合,以畜力原木集材为主,机械原条集材为辅。     

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.     

A Comparison of Productivity in Five Small-Scale Harvesting Systems

The use of small-scale harvesting equipment continues to grow in forestry in many regions of the world. This equipment includes various devices and methods used to harvesting that generally are smaller, less expensive and less productive than advanced forestry machines. The objective of this study is to compare the efficiency of five alternative extraction methods implemented in a harvesting unit located in a mixed beech and oak forest ecosystem in northwestern Turkey. A continuous time study was conducted during primary transport operations that included skidding with animal power, skidding with farm tractor, hauling with farm tractor, hauling with forest tractor, and extraction by skyline. Timber was skidded uphill on a skid trail, and an average skidding distance of 100 m for all haulage methods was considered. Average slope of the harvesting unit ranged from 20 to 40 %. Average productivities for respective haulage methods were 3.80, 6.25, 2.80, 5.25 and 10.09 m³/h. Significant differences were found between productivity of haulage methods using one-way analysis of variance. The extraction by skyline, skidding with farm tractor, and hauling with forest tractor were determined to be the most statistically different methods, the productivity of these methods was found significantly higher than the other methods. Skid trails are useful for shortening distances during forest operations and skidding with farm tractor is a productive method in small-scale forestry of Turkey.     

兴安落叶松人工林抚育机械作业效率的研究

通过对沾河林业局现有的兴安落叶松人工林抚育机械即割灌机、油锯、集材机械进行分析和研究,结果表明：国产机型与国外先进机型相比,还存在着很大的改进空间。短距离集材,畜力集材具有优势;随集材距离加大,拖拉机集材效率明显高于畜力集材。影响集材效率的关键因素是回空和重载时间。     

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.     

伐区作业类型划分与集材作业系统相适应性的研究

本应用模糊聚类分析方法,选取作业区坡度、单位面积出材量、集材距离以及地表承载能力等作为因子,对吉林林区伐区作业类型进行了区划。又应用层次分析法,对与每类伐区相适应的集材作用系统进行系统分析。     

小型环境友好集材装备的研究进展

在集材过程中,集材作业不当会造成林地的土壤压实,会对幼苗、保留木造成损伤,影响森林生态环境。本文介绍国内外集材拖拉机和集材拖车的研究进展,对国内外的集材装备存在的问题进行总结和陈述,根据以上分析得出今后集材装备设计的理念和发展方向。     

Derivation of stumpage value and logging costs for individual forest stands using aerial photographs and cartographic modelling

A procedure for calculation of stumpage value and logging costs of individual mature forest stands using aerial photo‐interpretation and a grid‐based geographical information system (GIS) is presented. The stumpage value may be computed from characteristics related to the trees, i.e. site index, stand mean height, crown closure, and tree species distribution, using price equations. By means of cost equations, the logging costs may be calculated from the tree characteristics and the terrain characteristics of slope gradient and skidding distance. The practical application of the procedure was demonstrated by a case study in a 710 ha forest area in southern Norway. The tree characteristics were determined by photo‐interpretation of individual stands. Skid paths for wood transportation from the stands to landings along the forest roads were delineated by photo‐interpretation of the ground conditions. Slope and skidding distances were derived by a digital elevation model and cartographic modelling. Finally, the photo‐interpreted tree characteristics and the computed slope and skidding distances were used for calculation of the stumpage value and the logging costs of each stand. According to previous tests, the accuracy of the procedure corresponded to the accuracy that could be achieved by the field‐survey methods used most frequently.     

不同采伐、集材方式对林地土壤理化性质影响的研究

选择５种不同集材方式的皆伐作业与采伐强度为３０％的择伐作业,进行土壤理化性质指标变化程度的比较。在考虑各种作业的集材量和集材道面积的情况下,经主成分分析得出不同采伐、集材方式对林地土壤理化性质的干扰程度。认为,以皆伐作业手扶拖拉机集材为最大,其次为皆伐作业土滑道集材,其余依次为皆伐作业半悬索道集材,皆伐作业手拉板车集材,皆伐作业全悬索道集材,最低为择伐作业人力集材。     

轻型索道集材与开路集材三大效益对比分析

为了研究科学合理的生态采运技术,在邵武二都林业采育场开展轻型索道集材与传统盘山开路集材方式的对照试验。以122-1-3伐区972m3的出材量计算,人工费按每工每日100元计,则索道集材的单位成本为104.65元·m-3,可比开路集材单位成本148.44元·m-3节约29.50%。随着人工费的增加,按每工每日80～140元计,开路集材成本增加明显,单位成本差额为34.47～67.03元·m-3。通过生态、经济与社会效益的比较分析,轻型索道集材优势明显,是一种有利于资源、环境、经济和社会可持续协调发展的生态集材作业模式,在当前劳动力成本剧增情况下,展望轻型索道集材在木材生产技术中的广阔应用前景。     

三角履带式集材机的设计与分析

通过对集材机行走系统的研究,设计了一台三角履带式集材机。介绍了集材机整机结构、三角履带结构,并分析计算了牵引力、功率。利用MATLAB对车辆稳定性进行分析,发现降低质心高度、减小质心偏移距离、增加轨距可提高车辆稳定性。计算得出其空载纵向上、下坡最大行驶坡度分别为38.4°、33.2°,满载时分别为37.6°、38.1°,横向匀速直线和匀速转弯最大行驶角度为26.4°、22.8°。利用Adams对坡度为25°时车辆上、下坡及横向直线行驶运动进行仿真,结果表明:车辆有良好的爬坡能力和行驶稳定性。该研究对集材机的发展有一定参考意义。     

发挥集材机械在山地伐区的作用与效率探讨

对现有的J50系列集材机通过加装起重架,在牵引钢绳的头部设计一个北方雪橇形状的工具铁撬、加装绞盘卷筒等对其进行改装,使其成为适应山地林区作业的集材机械,达到一机多用,从而降低购置设备的成本。     

对人工林生态集材的几点思考

我国的森林资源中人工林已逐渐成为主导林分,科学合理的生态集材方式对人工林的可持续发展具有重要的意义.本文就如何实现人工林的生态集材问题,分别从选择集材方式和确定采育模式两个方面进行探讨.     

FYJ-1型轮式抚育伐集材拖拉机应用经济效益分析

通过对FYJ-1型轮式抚育伐集材拖拉机与畜力集材两种生产作业方式进行比较,对两个冬运期集材作业的实测数据进行整理与核算表明,集材拖拉机比畜力集材生产方式的经济效益提高2.99倍,生产效率提高2～3倍。 FYT-1型轮式抚育伐集材拖拉机不仅适合在零星分散的森林抚育间伐场地作业,更适合在集中连片和远距离（800m以上）、坡度适中的场地作业。     

考虑环境保护的集材方式选择

通过对农用车、板车和人工集材3种集材方式的集材效率和集材成本比较，对森林环境因子和采伐后对山体滑坡影响的对比研究，从经济效益及生态效益2个方面综合考虑，为合理地选择集材方式提供科学依据。     

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.     

Factors Affecting Harvesting Intensity in Small-Scale Private Forests in Slovenia

Among other factors, harvesting intensity in private forests depends on property, resource and forest owner characteristics. The research was conducted in Slovenia, a Central European country with very fragmented and small-scale forest property, a large number of owners and co-owners and a long tradition of sustainable forest management. In the nationwide study, data from the Land and Property Register and forest inventory database were used to build a logistic regression model to identify factors that influence harvesting intensity. The results of the model revealed that growing stock, share of conifers, share of forest area under regeneration, total size of forest property in owner- and co-ownership, parcel size and accessibility of the forest area to forest operations increase harvesting intensity. Slope, number and age of owners and co-owners, and skidding distance negatively influence harvesting intensity. The results can offer useful information for policy and decision makers for formulating policy as well as implementing the most suitable mix of policy instruments.