生产工艺对巨尾桉/聚乙烯膜复合材料质量的影响

采用巨尾桉基材、胶合剂聚乙烯膜制备三层木塑复合材料,分析热压温度、热压时间、热压压力、施胶量这四个因素对复合材料胶合强度的影响。结果表明：在热压温度160℃、热压时间50s/mm、热压压力0.7MPa、施胶量为119g/m2的工艺条件下,巨尾桉/聚乙烯膜复合材料的胶合性能最优,能够达到II类胶合板标准。     

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.     

改性豆基蛋白胶黏剂的胶合工艺初探

以杨木单板为试材研究了改性豆基蛋白胶黏剂的胶合性能,采用单因素实验方法,探讨了改性豆基蛋白胶黏剂压制胶合板的胶合工艺。分析了热压温度、热压时间和涂胶量对三层杨木胶合板胶合性能的影响。结果表明:采用改性后的豆基蛋白胶黏剂,在压力为1.4MPa,温度为165℃左右,热压时间为1.4～1.6 min/mm,涂胶量为220g/m~2,压制的杨木胶合板胶合性能较佳且达到Ⅰ类胶合板的标准。     

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。     

无醛大豆胶制备胶合板工艺及性能探究

采用生物基无醛大豆胶,通过胶合板厂现有设备对大豆胶合板的制备工艺参数进行系列实验表明:杨木胶合板最佳涂胶量为340g/m~2(双面涂胶,下同)、热压温度105℃;桉木胶合板最佳涂胶量为380g/m~2、热压温度110℃;在1～6h闭口陈化时间内,杨木、桉木胶合板的胶合强度均略有降低,但均可制备出满足国家二类板强度要求的胶合板材。实际应用过程中,我们可以根据实际情况调整上述制备工艺,以达到最佳效果。同时,利用生物基无醛大豆胶制备的板材具有较好的耐久性。     

桉树木材旋切单板质量以及制造胶合板工艺的研究

对福建省主要桉树木材材性及其旋切单板厚度偏差、背面裂隙率进行检测分析,探讨木材旋切单板的适应性和制造胶合板的工艺并采用正交法优选最佳工艺参数。结果表明:尾叶桉单板背面裂隙率和单板厚度变动系数比尾巨桉小,尾叶桉用于旋切1.5 mm厚度单板质量较佳。尾叶桉木材制造胶合板较佳工艺参数:热压温度为130℃、单位压力为1.4 MPa、热压时间为1.35 min·mm-1、涂胶量为320 g·m-2。工艺条件对板材性能均有影响,桉树木材龄级对板材性能影响显著,随着桉树龄级的增大,板材性能有较大幅度提高,特别是静曲强度、弹性模量影响最为明显。     

阻燃桉树胶合板的初步研究

以磷酸二氢铵（MAP）溶液为阻燃剂,通过浸泡尾叶桉单板,研究了单板的载药量;以Ⅱ类胶合强度为指标,利用正交试验对常规胶合板生产工艺进行了优选。在此基础上,选取浸泡时间和最优生产工艺试制了阻燃桉树胶合板,并对其Ⅱ类胶合强度和燃烧性能进行了检测。结果表明：不同厚度尾叶桉单板的载药量随浸泡时间的延长呈现相似的增长规律;试验所得常规尾叶桉胶合板最优生产工艺为施胶量210 g.m-2、热压温度130℃、热压时间8 min,该条件下胶合板的Ⅱ类胶合强度达到了2.01 MPa;单板浸泡8h后,单板平均载药量为32.05 kg.m-3,所制得阻燃胶合板氧指数提高了13.9%,炭化长度减少了8.3 mm（26.2%）,阻燃性能明显提高,而胶合强度也达到了Ⅱ类胶合板的国家标准。研究初步证明利用常规桉树胶合板生产工艺生产阻燃桉树胶合板是可行的。     

涂胶量对胶合强度的影响

本文通过实验数据的整理,绘制出在一定工艺条件下桦木、柳桉、山樟三个树种胶合板的涂胶量与胶合强度的关系曲线,由此提出临界涂胶量的概念。同时对涂胶量、热压压力和胶合强度、木材压缩率进行研究,提出在胶合板生产中确定合理涂胶量值的方法,以保证在取得合格的胶合强度的同时,达到降低成本的目的。并对临界涂胶量值进行了理论分析。     

小球藻蛋白基胶黏剂的制备及其胶合性能研究

小球藻蛋白具有可再生、价格低廉等优点,可用于制备蛋白基胶黏剂。采用氢氧化钠(Na OH)、十二烷基硫酸钠(SDS)和三羟甲基丙烷三缩水甘油醚(TTE)改性处理小球藻蛋白后制备胶黏剂。多种方式表征结果显示,改性处理破坏了小球藻蛋白的球形结构,提供了更多的交联位点,从而提高了胶黏剂的胶合强度及耐水性能。在优化工艺参数:双面涂胶量400g/m2,热压压力1.5 MPa、热压温度150℃、热压时间8 min的条件下,制备的三层桉木胶合板的干、湿胶合强度分别为1.78、1.11 MPa,满足GB/T 9846—2015《普通胶合板》中II类胶合板的要求。     

改性豆基蛋白胶的热反应特性与胶合工艺

通过差示扫描量热法(DSC),测定改性豆基改性蛋白胶的热反应特性,确定热压温度参数;并采用正交试验法,探讨用改性豆基蛋白胶压制杨木胶合板的热压工艺.结果表明:在压力1.4 MPa,温度165 ℃,时间1.4 min/mm,双面涂胶量220 g/m2的条件下,试板的胶合性能可达到GB/T 9846-2004中普通Ⅰ类胶合板的要求.     

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。     

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.     

Key Habitats in the Norwegian Production Forest: A Case Study

This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes.