速生轻质木材制备高性能重组木的适应性研究

以低密度泡桐、杨树和柳树三种速生轻质木材为原料,利用纤维可控分离技术,将6~7 mm厚单板制备成纤维化单板,经过浸胶、干燥、热压制备重组木,探讨三种木材制备重组木的工艺特点和产品性能。结果表明,三种木材均适合用于制备高性能重组木;在重组木与木材密度之比约2.5时,泡桐重组木的吸水厚度膨胀率最低,杨木重组木的抗弯性能最好,柳木重组木的水平剪切强度最高。     

预压缩处理施胶技术提高杨木重组木尺寸稳定性的研究

高性能重组木制造技术可将速生材制造成具有高强度和天然木材纹理结构的新型木材,从而提高速生材的附加值.然而,采用此技术制备的重组木虽然尺寸稳定性显著高于传统工艺制备的重组木,但是仍不能满足室外用材的需求.为提高室外用重组木的尺寸稳定性,采用预压缩处理施胶技术对木单板施胶后制备高性能重组木,通过扫描电镜、压汞仪、激光共聚焦...     

高性能重组木制造工艺对其性能的影响

采用冷、热压两种生产工艺,分别制备不同密度的高性能重组木产品,并检测其物理力学性能。结果表明:两种生产工艺均可以制备出物理力学性能优良的高性能重组木,其中冷压-热固化法生产的重组木耐水性能良好;热压法生产的重组木的抗弯性能和抗剪性能更优。     

我国高性能重组木材料制备技术开发与应用及未来发展

在总结回顾我国高性能重组木材料的开发历程、研发进展和生产现状的基础上,提出了高性能重组木今后的研究方向和重点内容及未来重组木材料产业的发展建议。     

我国重组材料科学技术发展现状与趋势

重组材料作为我国创制的一种新型绿色环保材料,经过近20年的发展,已初步建立基础理论体系和工艺技术装备体系,重组竹和重组木实现了大规模工业化生产。剖析重组材料发展过程中面临的微观结构的重构过程与机制,密度对重组材料影响机制、界面性能、耐候性、表面性能等科学问题,以及重组单元制备技术、热处理技术、连续化浸渍技术与装备、重组单元整张化技术、热（冷）压成型等重大技术问题,深入探讨重组材料在户外景观、家居、地板、结构材等领域的发展前景。     

木材所2项专利产业化推进工程项目通过验收

<正>2014年7月,由中国林科院木材工业研究所承担的"纤维化单板重组木制造技术"和"木塑复合工程材料系列专利推广应用"两个林业专利产业化推进工程项目,顺利通过了国家林业局的验收。"纤维化单板重组木制造技术"项目,完成了纤维化单板展平疏解技术和酚醛树脂可控导入技术等关键技术的开发与转化应用;解决了重组木单元制备的关键技术难题;创制出具有自主知识产权的纤维化单板重组木;分别完成了桉树、杨木和桦木等人工林速生材纤维化单板制备的中试试验,以及重组木和重组木地板的中试试验,产品质量指标达到了     

新型纤维化单板重组木的主要制备工艺与关键设备

总结传统重组木的产业化发展历程和技术难题,提出先制备单板、再疏解纤维化单板、后重组的技术方案,介绍冷压热固化法和热压法制备新型纤维化单板重组木的主要工艺和关键设备。新型纤维化单板重组木突破了传统重组木采用原木直接碾压疏解制备木束的思路,解决了重组木产业化的技术瓶颈,为其产业化提供了一套可行的技术方案。     

不同单元形态木材增强重组竹结构材料抗弯性能的研究

根据混杂复合材料理论,探讨将几种不同单元形态的木材:木束、木刨花和木纤维与重组竹的基本单元--竹束,采用均匀混杂方法制备增强型重组竹结构材料的可行性,研究木束-竹束、木刨花-竹束以及木纤维-竹束的混杂比对增强重组竹结构材抗弯性能的影响.结果表明:与重组竹相比,当刨花-竹束以及纤维-竹束混杂比分别为10%、5%时,在垂直加载和水平加载方向上竹木复合重组结构材料的静曲强度和弹性模量综合增强效果最为明显,而随着木束-竹束混杂比增加,木束增强重组竹结构材料的弹性模量和静曲强度呈现先下降再上升的趋势,当混杂比为33%时负增强效应最大.     

小径木刨切单板纤维化处理设备整机结构设计

为突破传统重组木木束单元偏大、纤维形态不规则、疏解程度不均匀的缺陷,研发了一种能生产较小木束单元的纤维化疏解设备。在对现有疏解设备结构形式及工作原理进行分析的基础上,确定了小径木刨切单板纤维化处理设备的主要技术参数,完成了小径木刨切单板纤维化处理设备的结构组成设计,对机架、疏解机构等进行了合理设计和布局安排,其中包括疏解辊直径、辊齿参数、辊齿配置及微调装置的设计。采用该设备生产的纤维化单板具有纵向纤维不断裂、粗细较均匀的特点,且纤维束的宽度基本分布在1~3 mm,以该纤维化单板为基本单元制成新型重组木,能够得到不同性能指标的产品。小径木刨切单板纤维化处理设备是生产新型重组木的重要设备之一,可为制备新型重组木产品提供优质的原材料。     

疏解工艺对毛白杨与辐射松重组木物理力学性能的影响

以辐射松和毛白杨疏解单板为原料分别制备重组木,探究两树种单板的疏解工艺对其性能的影响。结果表明,相同疏解工艺条件下,辐射松单板的疏解效果优于毛白杨,制备重组木的物理力学性能亦优于毛白杨重组木。建议实际生产根据不同树种的组织结构差异,制定相应的疏解工艺,以满足重组木性能的需求。     

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.