伐区楞场位置决策研究

对影响伐区楞场位置的因素进行详细的分析，从木材生产经济效益的角度出发，提出对于不同的集材方式，以确定最佳的伐区楞场位置的数学模型。结合漳平市双洋镇的6个伐区小班加以实践。实践表明在一定的条件下，采用索道、板车、担筒三种集材方式楞场的最佳位置伸入伐区的程度从小到大。这个数学模型对于山区的伐区楞场位置的确定有一定的适用范围。     

伐区楞场位置决策研究

对影响伐区楞场位置的因素进行详细的分析,从木材生产经济效益的角度出发,提出对于不同的集材方式,以确定最佳的伐区楞场位置的数学模型.结合漳平市双洋镇的6个伐区小班加以实践.实践表明在一定的条件下,采用索道、板车、担筒三种集材方式楞场的最佳位置伸入伐区的程度从小到大.这个数学模型对于山区的伐区楞场位置的确定有一定的适用范围.     

南方集体林区采运工艺改革的一点突破——谈永安市国营伐木场建立中间楞场的技术、经济情况

伐区楞场在产、供过程中出现种种矛盾:木材储存不好,还不能及时运给客户等,所以需要建立独立的机械化选材、归楞和供货的场地——中间楞场,对其工艺和布局详细作了七点技术要求,其经济效益显著     

柴油绞盘机上安装发电装置

为了解决伐区楞场夜间装车的照明问题,我们在柴油绞盘机上安装了自动调速调压的发电装置,收到了比较好的效果。本文对其原理和结构做一简单介绍。     

低强度择伐伐区集材方式的探讨

这篇文章探讨了低强度择伐伐区集材方式，分析了各种集材方式的优缺点，讨论了新的集材工艺和集材方式。新的集材工艺和集材方式是：由轻型绞盘机或小型拖拉机或畜力将原木或原条运到集材道两侧，完成小集中作业；再由拖拉机或索道或畜力将这些原木或原条运到伐区楞场，完成集材作业。     

枝桠削片设备的研究

为了适应我国林业生产战线开展伐区剩余物利用的要求,我们进行了枝桠削片设备的研究工作,已先后研制成功可配套使用的BG型移动式滚筒剥皮机、LX-650型移动式联合削片机、MB-22型木片半挂运输车。这套设备可在山上楞场进行伐区剩余物(枝桠、树头等)的剥皮、削片,并装运下山,供作人造板和造纸工业等的原料。BG型移动式滚筒剥皮机     

亚太地区森林采伐作业规程对我国森林采伐工作的启示

《亚太地区森林采伐作业规程》的制定是提高亚太地区森林可持续经营和利用的一项重要举措。本文介绍了该规程的产生和主要作用以及对我国森林采伐工作有借鉴意义的森林可持续经营定义、森林采伐计划、禁伐区、道路、楞场和集材道的设计 ;定向伐木、原木造材、伐后伐区的恢复工作、采伐作业的监督和评估等内容。根据我国森林可持续经营的要求和林业生产实际 ,提出了我国应尽快制订新的采伐作业规程 ,建立示范伐区 ,加强采伐科技研究 ,形成监测和监督体系等建议。     

内蒙古大兴安岭林区的作业设计

文章从林区的实际出发 ,通过对内蒙古大兴安岭林区伐区采伐强度、采伐蓄积、出材量、出材率、割灌、伐开调查线 ,楞场、薪炭材下山等问题的论述 ,找出了林区设计和作业过程中存在的许多不足 ,并针对这些不足之处提出了相应对策     

关于伐区图绘制与伐区材积表使用问题的商榷

1.伐区图绘制 伐区图是三类调在的重要成果。图上的伐区面积、形态、小号线、集材道、楞场及所在林班等信息,满足了林场采伐工作的需要。但是这种图的小班界转绘到二类调查的基本图和林相图上比较困难,从而使林场森林资源档案难以搞准,以至失真。其原因是二、三类调查的图上缺少控制点,所谓控制点是指代区图在转绘到二类调查成果——1:2.5万的基本图上时起定位和控制作用的点,是转绘的依据。这种控制点在伐区图上有显示或文字说明,在二类调查的基本图上也     

翻臂式原条装车机的研究

翻臂式原条装车机的研究闫成忠，郭恒发（黑龙江省木材采运研究所）（黑龙江省朗乡林业局）曹均，郭廷民，牛凤玉，陈乃跃，续文清（黑龙江省木材采运研究所）（黑龙江省朗乡林业局）在我国东北和内蒙古林区木材生产中，大部分伐区楞场原本原条装车使用固定式架杆装车机，...     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.