集成薄木制造工艺研究

本研究选用水曲柳、核桃楸、长白鱼鳞云杉3个树种木材和水性高分子聚合物-异氰酸酯、单组分湿固性聚氨酯两种胶黏剂制造集成木方,然后进行薄木刨切,并对木方刨切的集成薄木的厚度偏差、表面粗糙度进行检测。结果表明,经水热软化处理后,湿粘法制作的集成木方经水热软化处理后胶层均未发生出现剥离现象;干粘法制作的集成木方经水热软化处理后,除水曲柳集成木方胶层发生部分胶层剥离外,而核桃楸和长白鱼鳞云杉集成木方胶层均未发现剥离现象;厚0．60mm集成薄木的表面粗糙度检测值均达到了GB／T13010—1991国标中相应树种的指标要求。     

人工林杉木结构集成材胶合工艺的研究

以人工林杉木为试验用材,采用水性高分子异氰酸酯胶黏剂,以单位压力、涂胶量和添加剂用量为试验因子,进行集成材的胶合试验,并对其胶合性能进行检验.通过试验结果分析,本试验范围内较优的胶合工艺条件为:单位压力0.8 MPa,双面涂胶量250 g/m2,添加剂用量为10%.     

软木贴面定向结构麦秸板的胶合工艺

为提升定向结构麦秸板的装饰性能,采用冷压法对其进行软木贴面处理,分析压力、加压时间、涂胶量、胶种对贴面板胶合性能的影响.结果表明:采用异氰酸酯胶,在压力1.0MPa、加压时间30min、涂胶量80g/m2(单面)的条件下,软木贴面定向结构麦秸板的表面胶合强度、浸渍剥离长度,满足GB/T 15104-2006《装饰单板贴...     

竹炭／TiO2复合体改性杨木单板的胶合性能

采用加压浸渍法将负载型光催化材料--竹炭/TiO2复合体渗入杨木单板中,运用正交试验方法对纳米TiO2改性杨木单板的胶合性能进行了研究,探讨涂胶量、热压压力与浸渍压力等因素对材料胶合性能的影响,并结合扫描电镜分析给出了制板的最佳工艺条件:热压压力为1.2 MPa,浸渍压力为1.6 MPa,涂胶量250 g/m2.     

杉木胶合板热压工艺研究

采用涂胶量、热压温度、热压压力、加压时间等4因素3水平的L9(34)正交试验,探讨以杉木间伐材和非规格材为原料制作杉木胶合板的热压工艺。结果表明:采用涂胶量280 g.m-2、热压温度125℃、热压压力1.0 MPa、热压时间1 m in.mm-1,制作出的杉木胶合板胶合强度达到GB/T 9846-2004中Ⅱ类胶合板的指标要求。     

速生杨木单板层积材冷压工艺研究

冷压制造结构用单板层积材时,单位压力、加压时间、陈放时间、涂胶量和胶种是影响其强度性能的重要因素,同时各因素的变化还直接影响到生产成本和生产效率。试验表明,理想的冷压工艺条件为:单位压力 0.98 MPa、加压时间 7 h、陈放时间 40 min、涂胶量 180g/m2（单面）。     

工程胶合木胶合成型工艺优化研究

以兴安落叶松Larix gmelini为原材料,以间苯二酚树脂为胶粘剂,较系统地研究了压力和涂胶量对落叶松胶合木胶合性能的影响规律,获得了优化的胶合工艺参数。结果表明:胶合木试件的剥离率随着胶合压力和涂胶量的减小而增大;剪切强度和木破率随着胶合压力的增加呈现出先增加后降低的变化趋势,随涂胶量的增加呈现先增加后保持不变的变化趋势;胶合木胶合成型的优化工艺参数为胶合压力1.25 MPa、双面涂胶量300 g/m2。     

尾叶桉单板胶合性能的初步研究

根据尾叶桉(E.urophylla)木材的特点,采用单因素试验方法,探讨了尾叶桉生产胶合板的可行性。重点讨论了胶合板的热压工艺(热压压力、热压时间、热压温度)和涂胶量以及心边材对三层胶合板胶合性能的影响。结果表明:在未采用厚度规时,压力为1．2MPa,温度为140℃左右,热压时间为0．8～1．1min／mm,涂胶量为250g／m2,用pH值为 12．5的PF胶,生产出的桉树胶合板胶合性能较佳。     

胶合工艺对桉/杨Ⅰ类胶合板胶合强度的影响

按树和杨树是种植广泛的人工林树种之一,利用其制造结构胶合板意义大重.通过测定不同热压温度、时间、压力和涂胶量条件下,桉杨混合组坯结构胶合板的胶合强度,发现4个因子对胶合板的胶合强度均影响显著.本试验范围内,较优胶合工艺参数为:热压温度145℃、时间1.5 min/mm、压力0.8 MPa、涂胶量320 g/m2.     

柳杉实木胶合工艺及性能研究

为开发柳杉非结构用集成材,以剪切强度、木破率、浸渍剥离率为考核指标,进行柳杉实木胶合工艺及性能的研究。结果表明:柳杉木材可用于非结构集成材的制备,较优的胶合工艺为:压力1.0 MPa、加压时间30min、涂胶量180g/m2,胶合时按"弦切面-弦切面"纹理组合,其性能指标可达到日本标准JAS SE-8的要求。     

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.