Stumpage value in the short wood system for the conversion into high forest of a oak coppice

This study aims to analyze the factors affecting the costs of different logging systems, in particular considering three different bunching-extraction methods. Moreover the stumpage value of each plot was calculated, and a comparison analysis of the results is presented. The work was carried out in Central Italy, in an aged Quercus cerris L. coppice in hill zones, with a 45% average slope. Short wood system harvesting was applied. Felling and processing were performed by chainsaw, while extraction with three different methods: plot No. 1 with mules, plot No. 2 with a tractor with winch, plot No. 3 with polyethylene chute line. Transport of firewood from the forest track to the landing was made by a tractor loaded as a mule. In the plot No. 1 the costs per unit mass (30.76 ? 33% -1 ) were higher despite having the lower cost per hour (39.99 ? -1 ). The reason was the lower productivity (1.3 t 33% ·h -1 ). The plot No. 2 had the highest cost per hour (66.79 ? -1 ). However, productivity was the highest (2.7 t 33% ·h -1 ). This aspect was notable from the financial point of view (24.74 ? 33% -1 ). Plot No. 3 was the less expensive (23.92 ? 33% -1 ). Comparing the three methods, a reduction of the costs through more appropriate extraction systems may increase the stumpage value from 8.3 to 9.65 ? 33% -1 .     

The policy analysis of governing illegal logging: A game theory approach

Illegal logging has attracted worldwide attention, and some measures, such as timber procurement policies and timber regulations, have been taken. However, there are no studies that examine the governance of illegal logging using game theory. This paper applies game theory to analyze the subsidy policy for governing illegal logging as well as the effects of the subsidy on the benefits of suppliers and operators of forest products. The results show that controlling illegal logging has an impact on exporting enterprises, and the effects produced by subsidies and non-subsidies are different for enterprise. Enterprises that receive subsidies will occupy foreign markets and gain additional profits, while enterprises that are not subsidized will exit foreign markets. The amount of subsidies is related to enterprise’s governance cost. The benefit for operators and suppliers depend on the combination of supervision level and forest products’ legality. The critical point of regulation of operators is related to regulatory costs, the additional benefits of weak supervision of suppliers, and penalties for regulatory failure. The critical point for suppliers to select legal raw materials is related to suppliers’ operating costs, gray income, and the degree of punishment.     

人工用材林弥补天然林限伐"缺口"可能性分析

我国实施天然林保护,大规模调减木材产量成为必然.根据第四次资源调查的结果,对人工林产材能力进行了详细的测算,结论是我国人工林产材是在一定时期内不能弥补市场"缺口",增加木材进口是必然的.     

采伐小班(伐区)超证采伐现象剖析

伐区超证采伐和无证采伐是导致编限单位超限额采伐的主要原因,控制伐区超证采伐是保证限额采伐制度有效执行的关键措施之一。结合近年采伐限额执行情况检查的结果,对伐区超证采伐的类型、产生的原因、超证采伐量的确定等问题进行了探讨,并就如何控制伐区超证采伐提出了对策。     

刚果12号桉W5无性系立木木材密度与含水率关系的初探

本文主要是对刚果12号桉w5无性系立木材密度与含水率的关系进行分析和探讨。分析结果表明两者相关程度达高度紧密程度,相关显著性达极显著水平,回归公式估测精度甚高,回归方程在本林区适用。     

The role of timber tree species in the nutritional ecology of spider monkeys in a certified logging concession,Bolivia

Selective harvesting of timber can lead to population declines in some primate species. As frugivorous primates are important seed dispersers in tropical forests, the reduction of their populations may affect the ecological sustainability of selectively logged forests. This paper is the first to quantify the importance of timber tree species in the diet and nutritional ecology of a primate species. We studied spider monkeys (Ateles chamek) inhabiting a certified forestry concession in Bolivia where post-logging population declines of this species have been recorded. We show that spider monkeys occupying unlogged areas obtained approximately 50% of their total intake of macro-nutrients from timber tree species and exhibited a distinct preference for foraging within trees that were of harvestable size. Timber tree species dominated the spider monkeys’ diet both during peak fruiting periods and during periods of fruit scarcity. We estimate that under current timber extraction intensities spider monkeys lose significant proportions of their food sources. Our results indicate that further extraction limits could be considered for Ficus boliviana, Spondias mombin and Pouteria nemorosa. We suggest that to ensure long-term ecological sustainability of certified forestry concessions, the importance of timber tree species in the ecology of seed dispersers needs to be taken into account.     

浅析我国造纸工业木材原料市场及发展趋势

随着纸及纸板生产与消费数量的不断提高,我国造纸工业结构调整的发展对木材原料的需求将持续增加。我国木材市场数据显示,以原木、锯材等为代表的木材原料,以木浆、木片为代表的造纸原料进口均呈平稳增长趋势,木材市场供需矛盾突出。造纸工业竞争的核心是木材原料的争夺,而我国木材市场自有木材供给的严重不足性和进口总量的绝对依赖性特征决定了造纸工业木材原料未来仍将依靠进口。     

依据数理模型估算电信客户价值的应用探讨

探讨建立评估电信客户价值的算法模型。在算法中通过选取用户消费行为指标计算客户历史价值、当前价值和潜在价值，以此为条件计算得出个体客户的综合价值，最后据此估算值对存量客户群体按价值高低细分，达到在用户群体中建立客户价值评判框架的目的。该框架的建立和应用将解决电信企业对自身存量用户群体辨识不清的问题。为电信企业针对不同价值用户开展客户维系、挽留和价值提升工作，提供较为准确的判断依据。     

豫西山区日本落叶松人工同龄纯林立木形数数学模型研究

本文以豫西山区日本落叶松人工同龄纯林标准地的４７株平均木解析木为研究材料，计算立木形数，经计算机处理建立数学模型，并以模型为依据系统地讨论了形数与地位指数、树龄之间的关系。     

Division of afforestation site type in the watershed of Wangjiagou, West Shanxi through GIS

Using quantification theory I, an analysis of the relation of soil water and qualitative factors, such as, slope degree, slope aspect, slope position, and soil in Wangjiagou watershed area has been done. The study aims to quantify the factors influencing soil water, the descending order of the factors being the slope aspect, soil, slope degree, and slope position, thereby scientifically facilitating division of afforestation site types and afforestation site products digitally on geographical information system (GIS). __________ Translated from Journal of Northwest Forestry University, 2006, 21(3): 184–188 [译自: 西北林学院学报, 2006, 21(3): 184–188]     

市场经济条件下森林资源生态环境价值补偿问题

森林资源生态环境价值补偿,目前仍处在一个探索研究的过程,其实践性活动基本上没有进行。为了促进森林资源生态环境价值补偿活动有序的顺利进行,作者论述了森林资源的概念及森林资源与生态环境价值,提出森林资源生态环境价值的补偿。     

需求不确定条件下零售商主导的两级供应链博弈分析

研究市场需求不确定条件下零售商主导的两级供应链博弈均衡问题。应用Stackelberg博弈思想,验证供应链企业通过合作能够实现供应链整体收益最优及各自收益的最优。为了使供应链企业之间的合作保持稳定,供应链上的企业采用有回购契约的合作机制,从而实现链上企业的双赢。     

关于合理造材作业的几点探讨意见

本文论述了进入市场经济合理造材工作的重要意义;搞好合理造材工作的基本环节;量材设计是合理造材工作的关键环节;针对量材、造材作业提出了几点探讨性意见与建议。     

应力波法检测活立木品质的研究进展

介绍了应力波无损检测方法的基本原理以及采用该方法检测活立木品质的研究进展情况,阐述了应力波检测用于活立木品质研究的趋势。     

A new approach for the derivation of settings for machine graded timber

In this paper a new method for the derivation of settings for grading machines is proposed based on the fulfillment of basic statistic principles of regression, as well as the assumption that the distribution of the non-destructive indicating property of the machine and the model residuals are known. A system is introduced to quantify the uncertainty of the observations with the actual population they should describe. To verify the method the theoretical distribution of assigned strength grades is constructed together with a 90% confidence interval over which the destructive observations are expected. The strength grading system in Europe is based on strength, stiffness and density. Although in some cases stiffness or density may be the governing property this paper will focus on the case that the bending strength is the governing grade determining property. In this paper the principle of the proposed method is explained on simulated data and afterwards verified on real data for strength only. This shows good application for uses in practice. The verification showed that an incorrect combining of samples gives inaccurate settings for the intended grading area. With the proposed method the variation between samples can easily be taken into account.     

An improved technique for non-destructive measurement of the stem volume of standing wood

An improved technique, cheaper and less time-consuming, to measure standing wood volume by using an electronic theodolite was tested, by which greater information from the forest could be acquired accurately and non-destructively. This was achieved by recording the diameter at breast height and ground-level diameter of a tree as well as the included angle between the electronic theodolite and the left and right tangents of the stem at any point. The standing wood volume then was computed precisely by section. In addition, the factors that influence the precision of the method (observable distance and number of segments) were also analysed. In the study, 175 Larix gmelinii (Rupr.) Kuzen. trees and 190 Populus tomentosa Carrière trees chosen randomly for sampling were measured with the electronic theodolite, and then were cut down for measurement of the average cross-section volume. Based on the data acquired from 100 sample trees, a standard volume table was compiled, and then the data for the remaining random 10 sample trees in each group were selected for a comparison test. The results indicated that the optimal distance for indirect observation should be as high as the sample tree, and the optimal visual distinguished section was about 2?m. The correlation coefficient between the value measured non-destructively and the value of the felled trees of L. gmelinii was 0.97, with an average relative error of 1.62%. With regard to P. tomentosa, the correlation coefficient between the two values obtained by the two methods was 0.905 with an average relative error of 8.40%. It was concluded that the standard volume model based on the non-destructive measurement technique meets the requirements for precision in forest surveys. The precision of the standard volume model for L. gmelinii (a coniferous tree) was superior to that of the model for P. tomentosa (a broad-leaved tree). The electronic theodolite method provides an alternative technique for measuring trees without destructive sampling and is widely applicable for forest surveys.     

试论浙江森林资源的经济价值

从森林资源概念和范畴出发，应用国内外，具有一定代表性的林价理论，试按不同林种，年龄特点，分别采用林木市场价、林木期望价和林木费用价等不同方法评估我省森林资源的经济价值。     

植树挖坑机钻头主轴扭转振动数学建模与求解

介绍国内外机械化植树造林机械发展状况,指出国内植树用挖坑机研究重点,利用空间运动学和机械振动理论以及弹性动力学原理着重分析建立钻头主轴扭转振动模型并用数值方法进行求解,同时系统地分析钻头主轴下端部件与土壤的相互作用力、钻头主轴重力及惯性力等因素的影响,给出动态的准随机边界条件和初始条件.为下一步的钻头动力学特性仿真及整机动态特性研究,合理预测和控制钻头的运动规律,改善钻头的动力学特性,提高钻头工作效率及改进设计方法提供新的理论依据.     

Evaluation of the fire endurance of mechanically graded timber in bending

AbstractThis study examined the performance of mechanically graded timber in bending when exposed to fire at various load ratios. The test specimens were 150 pieces, each with the dimensions of 60 × 120 × 3500mm. The modulus of elasticity (MOE) of 150 specimens was measured, and 60 among them were selected to formulate the prediction equation for MOE and modulus of rupture (MOR), which was used to predict the remaining 90 specimens. These were tested under fire exposure in bending using three-point loading at 11.1%, 16.7%, 33.3%, 66.7%, and 83.3% of the ultimate load. Using mechanically graded timber, which means acknowledging the actual strength of the bending member, permits fairly precise application to the targeted design load. This research confirmed that mechanically graded timber under fire exposure has the following tendencies: under the same load ratio, time to failure is independent of strength class, and, at any load ratio, the critical strength is dependent on the timber strength class. The obtained design bending strength under fire exposure using the reduced cross section method and the reduced strength method conformed to those calculated based on Eurocode 5. Following those findings, mechanically graded timber can be applied to obtain the design bending strength when taking into account the fire attack.     

房屋建筑材用防腐剂的毒性试验

通过对十八种药剂配方(其中水溶性配方15种、油溶性配方3种)对木腐菌的毒性试验及对初筛后的配方进行流失后毒性试验,结果表明,水溶性配方中的铜铬砷即CCA_3、CCA_4、CCA_5,铜铬硼即CCB_5配方,以及油溶性配方中的P—B剂的毒性较大。