纯桉木纯杨木与桉杨组合实木复合地板性能比较的研究

通过正交试验研究了纯桉木、纯杨木与桉杨组合实木复合地板基材的最佳生产工艺,然后设计不同的桉杨组坯方式,研究纯按木、纯杨木与桉杨实木复合地板的性能.试验结果表明:桉杨组合生产实木复合地板是可行的,并且以桉杨组合方式五,即中间放置3层杨木单板,然后对称放置4张桉木单板,这样生产的实木复合地板的综合性能优于全桉、全杨和其他的桉杨组合方式.     

杨木单板异型家具构件的性能与质量分析

利用速生杨木单板,生产弯曲胶合异型家具构件.通过对其主要性能指标的检测,探讨以速生杨木单板为原料制造弯曲胶合异型家具构件的可能性,并对影响构件质量的因素进行分析.结果表明:杨木异型家具构件产品的性能.超过了相关质量标准的要求,可用于替代高档硬质实木使用,提升了杨木产品的科技含量和附加值.     

杨木和辐射松树脂增强改性材机械加工性能研究

为考察杨木和辐射松树脂浸渍材的机械加工性能,参照LY/T 2054—2012《锯材机械加工性能评价方法》,分别对杨木和辐射松的素材与树脂浸渍材及其经过真空热处理的树脂浸渍材的刨削、铣削、钻削、开榫和车削5种机械加工性能进行测试评价。结果表明:1)本试验范围内,在综合评分满分40分情况下,杨木素材、树脂浸渍材和真空热处理树脂浸渍材的总评分分别为20分、30分和25分;辐射松素材、树脂浸渍材和真空热处理树脂浸渍材的总评分分别为24分、33分和29分;树脂浸渍材机械加工综合性能最佳,热处理树脂浸渍材次之;2)杨木和辐射松的树脂浸渍材及其真空热处理树脂浸渍材的刨削、铣削性能均为优秀,车削性能均为良好;杨木和辐射松的树脂浸渍材及辐射松真空热处理树脂材开榫性能良好;钻削性能仅辐射松树脂浸渍材达到优秀;3)辐射松素材与改性处理材的机械加工性能均优于杨木,综合比较,辐射松树脂浸渍材具有较佳的机械加工性能。     

加拿大颤杨木材物理力学性能研究与评价

测试加拿大艾伯塔产颤杨木材的物理力学性能性能,并与国产部分杨木性能进行对比分析。结果显示,颤杨木材的密度较低,径、弦向干缩湿胀率差异较小;硬度较低,属软材,物理性能与国产杨木非常接近;其力学性能则优于国内杨木,可以作为国内杨木的补充,用于家具与木制品的生产。     

三聚氰胺脲醛树脂复配硼化物改性杨木的性能

采用硼酸、硼砂混合液,三聚氰胺脲醛(MUF)树脂及MUF树脂与硼酸、硼砂的复配改性剂处理人工林杨木,并对处理材的各项性能进行评价.结果表明:MUF树脂和MUF树脂复配硼化物的处理,均可显著降低木材的吸湿率,提高抗胀率、弹性模量和抗弯强度;3种改性材的氧指数均提高,点燃时间延迟,热释放速率、总热释放量、总烟释放量及CO产率均降低.以MUF树脂复配硼化物处理杨木的效果最优,杨木各项性能可全面改善.     

刨花模压托盘工艺

托盘是堆放和搬运货物的工具。用小径材、枝桠材生产刨花模压托盘代替实木托盘,以提高木材利用率。本研究用松木和杨木为原料,对生产模压托盘的关键工艺参数进行了研究。结果表明,刨花模压托盘的力学性能可达到实木托盘的性能要求。     

人工林杨木的用途选择——实木或单板层积材

实木材性对单板层积材强度的贡献率可衡量单板层积材强度中源自实木材性的份额,是人工林杨木单项用途选择的基础。本文以３个无性系实体杨木和由３种不同厚度杨木单板分别组配的单板层积材为对象,以由贡献率引出的实木与单板层积材的份率差值为依据,研究得出人工林杨木的最终用途选择。结果表明：６９杨、７２杨和６３杨３个无性系杨木的平均份率差值分别为５７％、－１５％、－２９％,说明６９杨宜用作实木,７２杨和６３杨宜用作单板层积材;杨木用作不同组配结构的单板层积材时,实木与３５６５ｍｍ、２６１４ｍｍ、１５４５ｍｍ３种厚度单板组配的单板层积材的平均份率差值分别为４３％、－１３％和－４３％,说明实木与较厚的３５６５ｍｍ单板组配的单板层积材相比,杨木宜用作实木,与较薄的２６１４ｍｍ和１５４５ｍｍ单板组配的单板层积材相比,杨木宜用作单板层积材。不同荷载作用的结果下用途选择结果显示,在抗剪强度、弹性模量和冲击韧性３项性能上的份率差值为正,此时杨木宜用作实木;在抗弯强度、抗压强度和硬度３项性能上的份率差值为负,此时杨木则宜用作单板层积材。     

黑龙江省木材科学研究所成果推介

正杨树是我国主要的速生人工林树种之一,具有品种多、适应性强等特点,但其材质松软、硬度小、强度低、易腐朽,只能作为低等材使用。黑龙江省木材科学研究所于2006年开展人工林杨木高端化利用研究,通过真空加压浸渍技术将浸渍强化药液浸入木材内,在杨木木材表层形成立体增强层从而大幅提高其物理力学性能,使之可以替代中等强度非结构用材,满足家具、室内装饰等用材的需要。"人工林杨木表面强化处理技术及设备研究与开发"是黑龙江省"十一五"科技攻关计划重点项目,     

黑龙江省木材科学研究所成果推介

<正>杨树是我国主要的速生人工林树种之一,具有品种多、适应性强等特点,但其材质松软、硬度小、强度低、易腐朽,只能作为低等材使用。黑龙江省木材科学研究所于2006年开展人工林杨木高端化利用研究,通过真空加压浸渍技术将浸渍强化药液浸入木材内,在杨木木材表层形成立体增强层从而大幅提高其物理力学性能,使之可以替代中等强度非结构用材,满足家具、室内装饰等用材的需要。     

桉木与杨木阻燃胶合板的性能对比分析

采用磷氮硼复合阻燃剂浸渍处理桉木和杨木单板,分别制备5层阻燃胶合板,检测其物理力学性能和阻燃性能.结果表明:阻燃胶合板的胶合强度,均满足GB/T 9846-2004《胶合板》中Ⅱ类要求,抗弯性能满足LY/T 1738-2008《实木复合地板用胶合板》要求;两树种胶合板相比,杨木阻燃胶合板的胶合强度较好,桉木阻燃胶合板的抗弯性能及阻燃性能更优.     

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.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

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。     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.