割灌机幼林抚育的成效分析

分析了当前大面积人工造林带来的抚育压力大、抚育成本高的问题,对比了割灌机实施幼林机械抚育与人工镰刀抚育效率和成本,探讨了割灌机在幼林抚育中的优势,指出了割灌机对进行幼林抚育,降低森林培育成本,提高林业生产力具有积极的推动作用。     

综合信息

国家林业局规范人工商品林采伐国家林业局发出的《关于完善人工商品林采伐管理的意见》,要求各级林业主管部门切实加强对人工商品林采伐的经营管理,增加森林资源总量,提高森林资源质量,促进森林资源     

撫育伐新机器

由于撫育采伐在各种不同的条件下进行,所以对作业机械和机器的要求較高。为实現撫育伐作业机械化,全苏林业和林业机械化研究所設計了一种CMA-1自行摩托切割机,用于在树龄为25年以下的人工幼林和天然幼林中,进行透光伐、除伐和疏伐时择伐乔木和灌木;也可用于純林和混交林中,     

试论自行式采伐机械在我国应用的合理性

一、前言近年来,森林工业发达国家(美、加、瑞典、苏、芬)研制和生产出许多种高效率的自行式采伐机械,使生产效率大为提高。这些机械,既有多工序机械(采集联合机),也有单工序机械(如伐木机、打枝机等),为同传统的手持采伐机械(如油锯)相区别,我们把它们统称为自行式采伐机械。这类自行式采伐机械的出现和应用,也引起了我国广大林业工作者的重视。我国在     

天保工程区人工商品林采伐管理办法探讨

天然林资源保护工程区内禁止对天然林进行商品性采伐,但如何对区内人工林施行商品性采伐,需要一个探索过程,原有的林木采伐管理办法已与当前林业发展的形势不相适应。文中提出了改进人工商品林采伐的政策措施,并对完善人工商品林采伐管理办法进行了探讨。     

对内蒙古大兴安岭林区森林采伐方式的浅析

大兴安岭林区山势平缓,森林类型比较简单,天然更新和人工更新都比较容易,只要采伐方式得当,完全可以建设成“青山常在,永续利用”的林业基地,下面仅就大兴安岭林区的采伐方式作一粗浅分析: 一、径级择伐采伐方式建国后,从1949年到1955年期间的采伐方式全部是径级择伐。当时对落叶松规定胸高直径30厘米以上的采伐,1955年又规定胸高直径20厘米以上的就准许采伐;对白桦、杨树规定胸高直径20厘米以上的采伐,1955年又规定胸高直径16厘米以上就准许采伐。这个时期     

昭通市天然林保护工程区人工商品林抚育采伐探讨

昭通市现有人工商品林面积达15.72万hm2 ,蓄积715.80万m3 ,存在着林分质量差,病虫害严重,火灾隐患大等问题,急需进行抚育采伐.对全市天然林保护工程区人工商品林采伐试点情况进行分析,认为:森林采伐管理对象不适应加快林业发展的要求,有待进一步调整;有关技术规程和技术参数已不适应集约经营的现代林业,有待于进一步修正;限额采伐管理制度不适应基层林业技术实际状况,有待于进一步优化.     

微型计算机在木材采运分析中的应用

由于木材采运成本高和用于森林经营的投资大,林业人员和按合同采伐的人员在不断寻找降低成本和提高采伐效率的采伐方法。过去几年,木材消费工业企业发现利用合同采伐者为他们工厂提供制浆木材,原木和木片比利用他们自己公司职员提供这些原料的成本更低。     

提高迹地更新质量的意见

森林采伐迹地更新,是林业生产的重要环节,更新质量好坏是关系到林业发展后劲的大事。为了探讨采伐迹地人工更新效果,1981年我们对柳河县八里哨、凉水河子两个林场近几年来的主伐迹地采取分年度随机抽取小班,在小班内随机设置标准地进行抽样调查。现根据人工更新及保存率的情况提出     

国家林业局关于完善人工商品林采伐管理的意见

各省、自治区、直辖市林业(农林)厅(局),内蒙古、吉林、龙江、大兴安岭森工(林业)集团公司,新疆生产建设兵团林业局:为促进人工商品林的培育和合理利用,规范人工商品林的采伐管理,根据《中华人民共和国森林法》、《中华人民共和国森林法实施条例》和《中共中央国务院关于加快林业发展的决定》的精神,现就人工商品林采伐管理提出以下意见。一、人工商品林采伐管理遵循依法治林、分类管理和可持续经营的原则。二、人工商品林包括人工培育的用材林、薪炭林和经济林。人工用材林是指人工培育的以生产木材为主要目的的森林和林木,包括人工播种(含…     

Mechanized thinning of walnut plantations established on ex-arable land

The study compares two product strategies—chips versus firewood—and two technological levels—manual versus mechanized—as applied to the thinning of walnut agroforestry plantations, established on ex-arable land. Such plantations are widespread all across Europe, and their establishment was subsidized under the provisions of EU Directive 2080/90, and of regional grant schemes. Field test data were used to build a simple deterministic model for estimating thinning productivity and cost under varying work and economic conditions. This model can assist prospective users when checking the profitability of an operation, or when assessing the competitiveness of alternative options. Removing nurse alder from young walnut plantations yields between 25 and 50 t of fresh biomass per hectare and is crucial to the good development of the stand. The study shows that the removal of nurse alder from walnut plantations is economically viable, and it can also offer some profits if stand and market conditions are favourable. As a rule, the average DBH of removal trees should not be smaller than 12 cm. Best results are obtained with mechanized harvesting, which does not seem to cause heavier stand and soil damage than manual harvesting. Manual harvesting is preferable only if the annual utilization of machinery is very low, and in this case it should be geared to firewood production. The manual whole-tree harvesting (WTH) method used in this study offers the lowest performance under all conditions, and should be replaced with some other manual alternative to WTH. Mechanized WTH offers a significant cost reduction over mechanized short-wood (SWS) harvesting, but this difference is still rather limited: hence, other parameters come into play when deciding what system to apply, and namely product price and mass output. In this respect, one also has to consider the cost of managing the harvesting residue, and that of fertilizing, if soil nutrient depletion is to be feared.     

森林采运系统动力学模型研究

为了分析森林采运系统的效率和成本,本文选择系统中关键的采—集过程,利用系统动力学的方法建立模型,进行计算机仿真模拟。结果显示,以特定时间范围内完成一定工作量为前提,系统运行的效率和成本与初始设备的投入量关系不大,与设备条件、外部条件、林木条件等关系很大。但初始采造设备的投入量会影响集材设备的运行效率和成本。在实际生产中,首先应根据林木条件和外部条件选择合适的设备,这样才能使得运行效率最高而成本最低;其次在设备的安排上,应充分保障采造设备,但也不应使其生产力与集材设备的生产力相差过大,否则会造成后期集材设备需求激增等问题。     

Cost, energy and carbon dioxide (CO2) effectiveness of a harvesting and transporting system for residual forest biomass

The purpose of this study is to examine the feasibility of a system to harvest logging residues (or slashes) as a new resource for energy in Japan. A harvesting and transporting system for residual forest biomass was constructed with reference to some European countries where the utilization of bioenergy is making steady progress and examined on the basis of field experiments in Japanese forestry. The feasibility of the system is discussed from the standpoints of cost and energy, and the system is compared with those of the European countries. With respect to the system proposed in this study, it is desirable that the process of chipper comminuting is incorporated into the system as early as possible, considering the trends of harvesting cost and fuel consumption per unit weight of residual forest biomass. Such a system is not particularly feasible in Japan from the standpoint of the harvesting cost per MWh of bioenergy. However, no specific problems are found from the point of view of the energy input rate, and it is clarified that it is possible for Japan to reduce domestic carbon dioxide emissions by utilizing biomass as an energy resource. A comparison with the European countries and a preliminary sensitivity analysis of the system demonstrate that the technical development to reduce the harvesting cost,e.g., improving the forwarding and transporting efficiency, and support from the government are essential for realizing bioenergy utilization in Japan. A part of this paper was orally presented at the 111th Annual Meeting of the Japanese Forestry Society (2000). JSPS Research Fellow. This study was supported in part by a Grant-in-Aid for Scientific Research from the Japan Ministry of Education, Science and Culture (No. 10460061).     

Efficiency of alternative forest inventory methods in partially harvested stands

Forest inventory is vital to all aspects of forest management and inventory methods can vary greatly in their accuracy, precision, efficiency and cost. In Maine, much of the forestland base has been managed using partial harvesting methods over the past two decades. These partial harvesting methods generally produce highly heterogeneous stand structures and composition. Consequently, it is currently unclear which inventory methods are best given the distinct spatial and structural heterogeneity that is created. We compared efficiency and stand-level inventory estimates using horizontal point, fixed area and horizontal line sampling measurement methods in 16 partially harvested stands across northern and central Maine. Some stand-level variables were sensitive to measurement method (e.g., volume, quadratic mean diameter and small stem density and basal area), while others were less sensitive (e.g., overall basal area and stem density). Efficiency, defined as a combination of precision of volume estimates and measurement time, varied among measurement methods at lower stand basal area values but was similar at higher basal area, with the exception of the fixed area method. Overall, horizontal line sampling proved to be a viable method in post-partial harvest stand conditions. Our results illustrate the trade-offs between precision and time costs involved in several measurement methods under a range of heterogeneous stand conditions.     

Efficiency of Iranian forest industry based on DEA models

Data Envelopment Analysis (DEA) is a mathematical tech-nique to assess relative efficiencies of decision making units (DMUs). The efficiency of 14 Iranian forest companies and forest management units w...     

Application of a Small-Scale Equipment System for Biomass Harvesting

The small-scale harvesting equipment system has been and continues to grow in use in forestry operations in some regions in the world. This harvest system can include a range of equipment types, such as feller-bunchers or chainsaws, skidders or farm tractors, and chippers. These machines are generally smaller, lower cost and less productive than larger, more advanced forestry machines. The objective of this project was to investigate the feasibility of a small scale harvesting system that would produce feedstock for a biomass power plant. The system had to be cost competitive. A boom-type feller-buncher, a small grapple skidder and a chipper were tested as a small-scale system. In this study, feller-buncher and skidder productivity was determined to be 10.5 m³ per productive machine hour, and production for the chipper was determined to be 18 m³ per productive machine hour. Production from the system did not reach the desired levels of 4 loads/day (25 m³/load); however, the system was able to produce about 3 loads/day. The results showed that the system currently could fill a roadside van for $16.90/m³, but suggested machine modifications could potentially reduce the system cost to $12.73/m³. Residual stand damage was minimal, especially on flatter ground and not operating on a slash layer. Soil disturbance from the harvesting system was predominantly undisturbed or classified as a shallow disturbance.     

A Survey of Logging Contract Rates in the Southern European Alps

A survey of harvesting contracts was conducted in the Alpine regions of France and Italy. The main goal was to produce a benchmark for the harvesting contract rates in the area that may guide forest owners and logging contractors when making their harvesting decisions. The sample included 443 contracts, evenly distributed between France and Italy. The mean tract size was 9.17 ha, while the mean lot size was slightly larger than 500 m³ under bark (ub). Mean removal intensity varied from 70 to 120 m³ ub ha^?1, depending on country and harvesting technique (i.e. ground-based or cable-yarder based). Mean contract rate was 35€ m^?3 ub, but individual contract rates varied significantly between countries and for different harvest techniques. Regression analysis showed that contract rate was strongly affected by tree size, extraction distance and harvest technique. Contrary to expectation, neither tract size nor lot size had any effect on contract rate. This may be explained by the widespread use of mobile operations that are specifically designed for handling small lots and incur minimum relocation cost. The technical factors explored in the study could only explain 40 % of the variability in the dataset, and therefore at least part of the variability must derive from non-technical factors such as local market dynamics and national economics. The study did find significant differences between countries. In particular, ground-based operations were more cost efficient in France, and cable yarder-based operations in Italy.     

The effect of harvest tree distribution on harvesting productivity in selection cuts

Abstract

The study explored the effect of tree-selection pattern on harvesting productivity, under specific site conditions typical of mountain forestry and suitable for mechanized cut-to-length harvesting. In particular, the experiment tested two different single-tree-selection principles, namely, uniform spatial distribution across the whole site and clustered distribution, where selection trees were concentrated along presumed strip roads. The test was conducted on two different sites, representative of two different stand-development stages. Ten plots were located on each site, and randomly assigned to the two spatial distribution treatments (uniform and clustered). Great care was taken to maintain even conditions for the test. Mean tree size and removal intensity were the same on all plots from the same site; all plots were harvested by the same harvester and forwarder team; data were collected by the same researchers in all plots. Under the specific conditions of the study, the spatial distribution of harvest trees had no significant effect on harvesting productivity and cost. In contrast, harvesting performance was affected by tree size and possibly removal intensity. Anecdotal evidence about the effect of spatial distribution on harvesting cost may derive from its possible association with the other above-mentioned factors (e.g. tree size or removal intensity).     

枝叶采收对人工云南红豆杉叶构件种群特性的影响

本研究对云南省马关县的6年生云南红豆杉人工林进行了采收主干及其上部枝叶、保留主干采收其上部枝叶、保留主干采收其下部枝叶3种采收方式下3个采收强度的试验,通过1年的持续观察,以不采收枝叶的植株为对照,分析了枝叶采收对云南红豆杉叶构件数量及动态变化的影响。结果表明:3种采收方式均有随着采收强度的增加落叶量增多的现象,同时老叶落叶率随时间的推移呈递增趋势;采收可以促进新叶数量的增加,但是采收上部枝叶比采收下部枝叶对促进新叶数量增加的效果更明显;采收降低春叶密度,提高秋叶密度,新叶总体密度并没有随采收处理的不同而表现出显著差异;叶净增加量随3种采收方式的采收强度增强而增加。为收获更多的枝叶,提高来年枝叶的叶净增加量,采收主干及上部3/4树冠长度的枝叶和保留主干采收上部3/4树冠长度的枝叶较好,叶净增加量分别是对照的2.96倍和3.00倍。为使人工林持续发展,采收主干及上部3/4的枝叶处理是最佳的枝叶采收方案。