受变化力作用的集材杆受力的计算及绷索方位的探讨

在索道集材中,一般用一根集材杆来改变绞盘机钢索的牵引方向。为保持集材杆在集材作业中稳定,用几根绷索把它固定在附近的伐根上。正确地计算集材杆及绷索的受力,是保证集材作业顺利进行的基本条件。关于集材杆和绷索受力的计算方法,尤其是     

受变化力作用的集材杆受力的计算及绷索方位的探讨

在索道集材中,一般用一根集材杆来改变绞盘机钢索的牵引方向.为保持集材杆在集材作业中稳定,用几根绷索把它固定在附近的伐根上.正确地计算集材杆及绷索的受力,是保证集材作业顺利进行的基本条件.关于集材杆和绷索受力的计算方法,尤其是受变化力作用下的计算方法,目前文献上虽有几种,但都有一定的局限性.关于绷索方位同集材杆及绷索受力关系的研究,现有文献上尚不多见.本文根据集材杆及绷索在集材中的受力情况,考虑到主要因素的影响,提出适用于一般情况的计算方法和公式,并对绷索的最佳方位进行初步探讨.     

JSX3-1.5轻型自行式集材机的研究

为适应南方人工林集材与南方山区索道集材技术的发展，福建省林业科学研究院、福建省国有林场管理局共同研制成功了ＪＳＸ３—１．５轻型自行式集材机，并于２０００年４月５日通过省科委主持的技术鉴定，达到国内同类研究的先进水平．技术性能测试与林区生产性试验表明：该机自行性能、制动性能、转向性能、爬坡性能等均能满足林区道路要求；该机自带液压式可侧向折叠的两节式钢架杆与诸钢索导向滑车、绷索滑车、绷索卷筒－棘轮停止器等，使索道架设折转方便，省工省时．三个缠绕卷筒可单独供索道工作索进行开式牵引或改装作闭式牵引，后缠…     

直角集材的改进与安全作业

该作业现场是进行人工林的采伐,由于每年的作业现场分散,索道线路经常产生跨越幼龄林地的困难。因此于八○年的采伐作业中,采用起重索一端的增力循环牵引式集材索道,并且按直角(定向器)集材方法进行集材,因而消除了对幼令造林地的损坏。并计划改进架索安装,采用装设着侧臂导向架的跑车。但由于循环索和起重索、承载索等的相     

JS2—15型绞盘机及其索道系统的研制与应用

JS2-15型绞盘机及其索道系统,具有结构合理、轻便灵活、安全可靠、适应性强、维修保养方便等特点。适用于林区中幼林间伐或择伐和人工林主伐机械化集材作业。文内着重介绍了该索道系统各部结构特点和索道线路设计及安装架设技术以及在林场进行生产试验的结果。     

国外集材索道现状

目前,许多国家山地林区进行木材采伐作业多采用索道集材。罗马尼亚应用集材距离达一千米的自动跑车索道,也应用集材距离达四百米的简易索道(缆索起重机式)。简易索道起重量三吨,它由自行式驱动装置、跑车和钢索索具组成。它能逆坡集材,也能顺坡集材;能全悬式集材,也能半悬式集材。线路坡度达四十五度。这种索道也可以用来装车和小集中。索道的驱动装置(三卷筒绞盘机)和钢架杆装配在轮式底盘上。架杆高六米,装有穿过承载索、牵引索和超重索的滑车。当坡     

南方人工林曲线索道集运间伐材经济效益分析

1985年以来,福建、广东两省先后自制和从日本引进,以活立木做支架,可在林内根据需要任意穿行的曲线索道。该设备通过人工林抚育间伐集运材试验,取得良好效果。但是,人工林在第一次间伐时尚处幼林时期,立木径级小、材质脆,难以找到可做支架的立木,不宜采用曲线索     

运行式索道的故障排除及搬迁

运行式索道虽然较其它类型索道架设搬迁方便,但故障排除、搬迁仍是消耗工人体力最大的一项工作。如何最大限度降低工人的劳动强度,是摆在高坡集材方面的迫切任务。特别是使用大功率绞盘机进行集材作业,断索事故频频发生,有时一个台班要发生1~3次。因此,选择简单、方便、快速的故障排除方法对木材生产具有重要意义。一、断索的故障排除运行式索道集材时,要想使原条抬头,必须在绞集牵引索同时制动回空索,导致牵     

曲线索道试验简介

在我国南方和西南林区,山高坡陡,地形复杂,架空索道集材是一种比較理想的集材作业方式。經过几年来的試驗,直綫架空索道已經比較广泛地运用在南方和西南林区的木材生产中。但是在一些地形极其复杂,而且箐沟弯度較大的地区,采用一条直綫架空索道来解决整个箐沟的木材集运作业,往往难以滿足需要,而不得不用数条直綫索道接力的方式解决。目前,在云南省拉姑林业局大河林场就出現了三条直綫索道接力的情     

集材索道钢丝绳拉力的测试装置

在木材生产中,南方林区和北方高山林区都使用了各种集材索道。对索道的设计、安装架设和使用都是根据现有公式计算的,但对索道中钢丝绳在各种运动状态下的受力情况测试较难或无法测试,在合理选用钢丝直径、确保合理的安装拉力等方面都产生一定的困难。所以,当钢丝绳工作时,在不同运动状态下所承受的拉力的测试是非常重要的。     

影响伐区作业的生态因子分析研究

本文从森林生态和森林采伐的关系入手,分析影响伐区作业的生态因子。这些生态因子包括林地坡度,林分结构、地表植被、采伐方式、采伐强度、集材方式、集材道间距、迹地清理方式,以及更新方式等,而林地坡度、采伐方式、集材方式、迹地清理方式和更新方式等是影响伐区作业的主要生态因子。     

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。     

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.     

轻型绞盘机小集中方法的探讨

本文对利用轻型绞盘机小集中作用进行了探讨。该方法对目前实行的大面积低强度择伐，低产林抚育和人工林间伐集材作业方式的改革将起到推进作用。     

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.     

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。     

Review of Studies on Structural Features,Regeneration Features and Management of Natural Spruce-Fir Mixed Stand of Coniferous and Broadleaved Trees in China

Natural spruce-fir mixed stand is one of the main forest types in the world,and also has huge ecological,economic and social benefits.According to the structural characteristics and succession laws of natural spruce-fir forest,it is urgent and significant to develop scientific management measures for natural spruce-fir mixed stand in line with local conditions.The article outlined the characteristics of the distribution and structure, regeneration and succession laws of natural spruce-fir forest,and analyzed the current situation and existing problems of natural spruce-fir forest management.The following recommendations were eventually made:1) In no cutting area,all logging activities should be banned.In a restricted cutting area,the cutting intensity should be generally controlled within 15%of the stock volume before cutting.On the commodity forest management area, the appropriate cutting intensity should be determined according to the volume per hectare,determine and classification management should be implemented in accordance with the characteristics of forest,to ensure the scientific selective cutting.2) Closure for afforestation,planting and repair planting should be adopted on vegetation-intensive land,sparse shrubs covered land and harvesting slash,in order to accelerate natural regeneration.3) The in situ conservation should be conducted in nature reserves and scientific experiment stations of rare and endangered species,such as Abies chensiensis,Picea neoveitchii,Abies vuanbaoshanensis,to reduce human destruction.4) It is supposed to collect seeds in time,establish nursery,actively establish forest, expand artificial population and promote natural regeneration.     

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.     

我国天然云冷杉针阔混交林结构特征、更新特点及经营管理

天然云冷杉林是世界主要森林类型之一, 具有重要的生态、经济和社会效益。探明天然云冷杉林结构特点和演替规律, 制定科学的经营管理措施, 因地制宜地合理经营云冷杉林意义深远而迫切。文中概述了我国天然云冷杉林的分布、结构和更新演替特征, 分析了经营管理现状及存在的问题, 并提出建议:1)对禁伐区内的云冷杉林分, 坚决杜绝一切采伐活动; 对限伐区要严格控制采伐强度, 一般控制在伐前蓄积量的15%以内; 对商品林经营区可按每公顷蓄积量的大小确定适宜采伐强度, 并按照林分特点进行经营, 做到科学择伐。2)对林地草本植被密集、灌木覆盖度不大、采伐迹地上有种源条件的进行封育、栽植或补植, 人工促进天然更新。3)建立秦岭冷杉、大果青杄、元宝山冷杉等珍稀濒危物种自然保护区和科学试验站, 积极开展就地保护, 减少人为破坏。4)适时采种, 就地建立苗圃, 开展育苗造林, 扩大人工种群, 促进天然更新。     

基于无人机影像的天山云杉林伐后更新地林分密度估测研究

【目的】林分密度是影响森林生态系统结构和功能的主要因素,是森林资源调查的一项重要指标,对林木生长发育有着十分重要的影响。基于无人机影像,以实现提取不同郁闭度的林分密度,旨在为天然林保护工程实施后山区森林资源更新恢复评价提供技术支撑。【方法】以新疆农业大学实习林场伐后更新的天然林为研究对象,以天山云杉Picea schrenkiana var.tianshanica纯林为主,基于无人机影像,利用面向对象多尺度分割方法提取了低、中、高3种不同郁闭度林分的天山云杉冠幅信息,进而估算林分密度,提出了采用平均冠幅法估测高郁闭度林分冠层遮挡区域林木株数的方法。【结果】采用面向对象方法对新疆农业大学实习林场伐后更新的天山云杉树冠边缘信息提取精度较高,提取的林分密度与实测结果相近。其中低、中郁闭度林分中林分密度提取精度分别为0.9868和0.9333,高郁闭度林分中林分密度提取精度相对较低,为0.7657。【结论】总体来看,该方法用于研究区天山云杉林伐后更新地林分密度估测是可行的,采用树冠平均冠幅法能够快速准确地提取伐后更新造林地的林分密度。