桤木制浆造纸研究现状与我国桤木浆的开发利用

就桤木商用种植的生产潜力、制浆造纸和材性研究现状等进行综合评述。桤木是一种商用种植较有发展前景的阔叶树种,生长迅速、固氮能力强,木材性质类似于杨木和桦木,可用来开发研制不同的浆种,与针叶木浆或其它阔叶木浆配抄可以生产高质量的印刷纸和书写纸等。鉴于我国丰富的桤木遗传资源和现有的生产经营水平,大力发展桤木纸浆原料林,开发利用桤木木浆具有广阔的前景,对于缓解针叶木浆之不足,降低纸浆生产成本,使我国造纸业     

北美地区杨树木材利用现状与前景

过去20多年, 北美地区的杨树已经从杂草树种转变为产生巨大经济效益的用材林树种, 杨树木材因其具有较高纤维素含量和较低的木质素含量, 适合用作纸浆和纸制品的原料。杨木制浆方法有机械法、化学法、半化学法和化学机械法, 杨木浆可以作为高级纸、纸板、新闻纸和包装纸。杨木牛皮纸浆与针叶材牛皮纸浆混合, 具有良好的成纸性能, 透明度高, 适合制作高级用纸。杨木也是传统的锯材、单板和胶合板工业的原材料, 用来生产锯材、单板、胶合板、木质复合板、包装箱、集装箱、火柴杆和筷子等。最近10年杨木定向刨花板和结构复合板产量显著增加, 利用前景广阔。从资源生产的角度来看, 在改良木材化学组成、纤维质量和自然耐久性等方面进行木材性质改良的转基因杨树研究取得了长足进展。从资源利用角度来看, 高价值的工程复合板和高得率的纸浆和纸产品将会在未来发展中快速增长。     

Socioeconomic factors influencing global paper and paperboard demand

To clarify the socioeconomic factors influencing global paper and paperboard demand, a panel data analysis was conducted covering the period 1961–2014. This study used paper and paperboard demand as the dependent variable, and a country’s economic level, Internet usage rate, plastic packaging demand, and time trend as the explanatory variables. An inverse U-shaped quadratic relationship, such as an environmental Kuznets curve, was found between economic level and paper and paperboard demand, which saturates and begins to decline as economic level increases. The economic level representing the turning point differs significantly with the use, ranging from around 37,000 US$/person for newsprint paper to around 66,000 US$/person for printing and writing paper. For both newsprint paper and printing and writing paper, demand declines owing to the spread of the Internet as the economic level rises, although this reductive effect is greater for printing and writing paper than for newsprint paper. A substitution relationship is not found between wrapping paper and corrugated cardboard on the one hand and plastic packaging on the other hand as the economic level becomes higher.     

Planting spacing affects canopy structure,biomass production and stem roundness in poplar plantations

To improve the productivity and wood quality of poplar plantations, effects of four planting spacing on canopy characteristics, biomass production and stem roundness in poplar plantations were evaluated over 8 years. Planting spacing influenced canopy characteristics of the plantations, and further affected the understory vegetation and plantation productivity. Understory vegetation biomass and Shannon-Wiener index were negatively correlated with leaf area index, but both diversity indexes and aboveground biomass of understory vegetation were higher in stands with a wider spacing. Tree diameter growth increased with increasing planting spacing, while the increment in plantations of square configurations (5?×?5 m and 6?×?6 m) was higher than those with rectangular configurations (3?×?8 m, 4.5?×?8 m). The highest poplar biomass production was achieved in the plantation with 5?×?5 m spacing at age 8. Moreover, poplar trees showed a tendency with better stem roundness in a square configuration. The results suggest that planting spacing not only affect canopy characteristics, understory vegetation and tree growth but also wood quality, and square configurations (5?×?5 m and 6?×?6 m) could be a better option for poplar plywood timber production at similar sites.     

Potential forest biomass resource as feedstock for bioenergy and its economic value in Indonesia

Indonesia has abundant forest biomass resource, which should not be considered as a low economic value resource. This forest biomass resource can be converted into bioenergy through various technologies and it becomes one of sources in Indonesia's energy mix. This paper focuses on forest residues generated primarily from the harvesting of natural production forests and industrial forest plantations; and wood processing mill residues. The estimated total potential forest biomass in Indonesia for bioenergy in the year 2013 was 132 PJ. About 50.4% resulted from harvesting residues and 49.6% from wood processing residues. Riau province has the largest potential bioenergy followed by Central Kalimantan, East Kalimantan, East Java, South Sumatera, Central Java and Jambi, which all together accounted for 87% of total potential bioenergy. Moreover, three major islands accounted for 95% of total potential bioenergy. Using a conversion return approach, the economic value of forest biomass when it was pelletized was estimated to be about US$ 5.6 per ton wood residues. The economic value of forest biomass is more sensitive to changes in the price of wood pellet than to changes in the collection and hauling cost of wood residues.     

人工林杉木和杨树木材物理力学性质的株内变异研究

按照中国国家标准研究杉木和I-214杨树木材的抗弯弹性模量、抗弯强度、顺纹抗压强度和密度,同时按照日本国家标准研究2个树种的顺纹抗剪强度.结果表明:杉木的抗弯强度、顺纹抗压强度和密度由胸高直径处向上呈波浪形增加,抗弯弹性模量则稳定降低,但不同高度间杉木的物理力学性质没有显著差异;近树皮处木材的物理力学性质高于近髓心处木材,并有极显著差异.对于I-214杨树,只有抗弯弹性模量从髓心到树皮逐渐增加,其他的物理力学性质,最小值在从髓心到树皮的过渡区,最大值在近树皮处,从髓心到树皮,杨树的物理力学性质有极显著的差异.杉木和杨树的径面顺纹抗剪强度从髓心到树皮有极显著差异,并且近树皮的高于近髓心的木材,而弦面顺纹抗剪强度从髓心到树皮没有显著差异.木材密度与力学性质有很好的线性相关关系,木材密度是一个很好的力学强度的预测手段.     

杨木材性对酚醛树脂浸渍改性材的影响

采用低分子量酚醛树脂对速生杨木进行浸渍处理、干燥定型,使树脂固化制得改性材。试验表明：低分子量酚醛树脂对杨木具有较好的浸注性,改性材的密度和力学强度均有明显的提高,两组试件改性后浸注性和密度相差不大,但前期经过热水处理的试件改性后密度相对均匀,力学强度略好于直接浸渍的试件。杨木自身材性对改性后物理力学性能的影响各不相同,在实际生产中要根据指标的重要性程度选取最佳方案。     

利用杨树人工林剩余物生产刨花板可行性研究

The composite board industry in Iran is obliged to use residues from forest operation as well as wood industry for competing with paper industry because of shortage of wood. In the present study we investigated the residues from poplar plantation used for particleboard production. Three kinds of wood materials, poplar branches, small diameter poplar wood (3–8 cm) and beech wood, were used in the experiment of particleboard production. The results demonstrated that the characteristic of particleboard made from poplar branches and small diameter wood is comparable to that made from mature beech wood. To avoid too much residual acid in the final board, the properties of boards produced with 1.5% hardener at 175°C press temperature are acceptable, although the properties of particleboard produced with 2% hardener were higher than were higher than that of the board produced with lower hardener (1% or 1.5%).. The MOR, MOE and IB of particleboard made from branches were measured as 14.57, 2015, and 1.32 MPa, respectively, while The MOR, MOE and IB of particleboard produced from small diameter poplar wood were 19.90, 2199, and 1.86 MPa, respectively. The thickness swelling of boards made from branches after 2 and 24 h immersion in water was 20.14% and 31.26%. The utilization of branches and very small diameter wood of poplar is recommended for the survival and developments of particleboard industry in Iran.     

Cost minimization through the use of taungya system in pulpwood plantation establishment

The costs and benefits of the use of three labour alternatives: direct permanent, direct casual and taungya labour in Gmelina arborea pulpwood plantation establishment in Nigeria were investigated. Results show that cost per hectare is lowest with taungya labour and highest with permanent labour with savings in cost of as much as 30% and 47% by taungya labour over casual and permanent labour respectively. The net present value per hectare of investment is highest when taungya labour is used and lowest and negative with permanent labour. Also, the internal rate of return of investment is highest with taungya labour and lowest with permanent labour. The net present values and internal rates of return for Gmelina plantations calculated for the three pulp and paper mills in Nigeria show the same trend in favour of taungya labour.     

A feasibility study of using two-component polyurethane adhesive in constructing wooden structures

This investigation was conducted to determine the feasibility of using a two-component polyurethane （PUR） adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate （PVAc） adhesive on block-shear specimens constructed of oriental beech （Fagus orientalis L.）, fir （Abies alba Mill.）, poplar （Populus deltoides Bartr.）, white oak （Quercus alba L.）, sycamore （Platanus orientalis L.） and white walnut （Juglans cinerea L.）. The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study.     

Model-based investigation on the effects of spatial evenness,and size selection in thinning of Picea abies stands

Size and spatial distribution of trees are important for forest stand growth, but the extent to which it matters in thinning operations, in terms of wood production and stand economy, has rarely been documented. Here we investigate how the choice of spatial evenness and tree-size distribution of residual trees impacts wood production and stand economy. A spatially explicit individual-based growth model was used, in conjunction with empirical cost functions for harvesting and forwarding, to calculate net production and net present value for different thinning operations in Norway spruce stands in Northern Sweden. The in silico thinning operations were defined by three variables: (1) spatial evenness after thinning, (2) tree size preference for harvesting, and (3) basal area reduction. We found that thinning that increases spatial evenness increases net production and net present value by around 2.0%, compared to the worst case. When changing the spatial evenness in conjunction with size preference we could observe an improvement of the net production and net present value up to 8.0%. The magnitude of impact differed greatly between the stands (from 1.7% to 8.0%) and was highest in the stand with the lowest stem density.     

Comparison of mechanical properties of tension and opposite wood in <Emphasis Type="Italic">Populus</Emphasis>

In this paper we focused on the differences of mechanical properties of tension and normal wood of 1-year-old poplar trees, artificially tilted. Elastic and fracture properties have been measured and linked to the anatomy. Tension wood is well known because it prevents good surface finishing and leads to difficulties with sawing. We studied three main mechanical properties: young modulus, energy of cutting and longitudinal residual strain of maturation (with strain gauges) because of their importance in wood technology. Moreover, this work takes place in a larger project of study, the phenomena of axes re-orientation in trees (allowing by the production of reaction wood), where these data are required for biomechanical modelling. The results show that tension wood has a higher young modulus, needs a higher energy to be cut and exhibited a higher level of longitudinal residual strain of maturation than those of normal wood. The results suggest that these differences require deeper analysis of the wood than anatomy: measurement of microfibril orientation in the S2 layer and also the lignin composition in monomeric units.     

林下耕作对滩地杨树木材物理力学性质的影响研究

本文对长江滩地这一特定立地条件下经过人为耕作与非耕作模式下的杨树木材物理力学性质及应力木分布情况与力学性质间的关系进行了比较研究。结果表明：林下耕作可提高杨树木材密度,与对照木相比,基本密度和气千密度差异性分别达显著与极显著水平;能够减少应拉木的产生,与对照木相比差异百分率达24．82％,进而使木材的差异干缩减小,木材尺寸稳定性提高;各项力学指标均优于对照杨树,且与应力木的量呈线性负相关,其中抗弯强度与抗弯弹性模量与其相关性显著。     

造林密度对欧美杨3品种在东北地区生长及材性的影响

[目的 ]为了探讨我国欧美杨速生丰产林良种选育及栽培环节存在的关键共性技术问题,在我国东北地区大凌河流域平原开展栽植密度对欧美杨品种的影响试验,为欧美杨纸浆材人工林优良品种的早期选育及推广栽培提供一定的理论依据。[方法 ]试验材料为京2杨、渤丰1号杨和渤丰3号杨3个欧美杨品种,设计2 m×3m、2 m×4 m、2 m×5 m和2 m×6 m四种造林密度。测量第2至8年的胸径,统计第1至8年的保存率,测定第1至8年的木材物理性质、第2、4、6、8年的木材解剖性质,测定总体的木材化学成分;整理并绘制保存率连年变化图,利用双因素方差分析逐年评价品种、造林密度以及品种与造林密度的交互作用对欧美杨胸径的效应,并对各性状进行多重比较。[结果 ]品种和造林密度对胸径生长均有极显著的影响(p <0.01);造林密度与品种的互作效应在第1至6年均是显著的(p <0.05),第7、8年则没有出现显著性(p>0.05)的互作效应。各造林密度中京2杨的保存率呈逐年较大幅度下降的形式,在第8年其各密度胸径和保存率最差,保存率最高的是2 m×6 m造林密度中的渤丰1号杨;胸径最大的是2 m×6 ...     

我国杨树人工林材性与加工利用研究现状及发展趋势

本文概述了杨树人工林发展概况,全面分析了杨树人工林木材性质与加工利用研究现状和存在问题,指出将杨树人工林材性与加工利用结合起来进行研究是合理、高效利用杨树人工林木材的必由之路。     

Effect of stand and tree attributes on growth and wood quality characteristics from a spacing trial with Populus xiaohei

The effect of stand density (1000 stems/ha, 500 stems/ha and 250 stems/ha) on tree growth and wood quality characteristics was studied in a 27-year-old plantation species of Populus xiaohei in China. Results indicated that stand density had significant effects on tree radial growth and crown size, and the lowest stand density produced trees with the largest stem taper. In terms of wood quality characteristics, there was no significant effect of stand density on either wood basic density or fiber length. However, significant differences were found between different stand densities for wood mechanical properties. A positive relationship between modulus of elasticity, compression strength and stand density was observed, while the highest modulus of rupture was recorded at a moderate density of 500 stems/ha. Stand density was responsible for highly significant effects on both juvenile wood and wet heartwood basal areas in individual trees, and there was an obvious tendency towards increasing juvenile wood and wet heartwood basal areas with decreasing stand density. In addition, the relationships between wood quality characteristics and tree and stand characteristics were also examined. Some wood quality characteristics, namely mechanical properties and juvenile wood and wet heartwood basal areas, were quantified successfully in relation to selected tree characteristics using a regression approach with various degrees of goodness of fit. Based on comprehensive consideration of various factors, such as wood quality, tree growth, and establishment cost, results from this study suggest that a density of 500 stems/ha is optimum for wood production.     

杨树工业用材林的定向培育

本文列泽了国外利用杨树作为工业用材和采取定向培育所取得的成功经验。讨论了我国杨树人工林发展的现状及存在的问题,为杨树人工林朝着具有“定向、速生、丰产、优质、稳定、高效”等目标发展提供了参考性建议。     

南方地区杨树胶合板材定向培育技术的研究

随着工业技术的发展,工业生产对木材和其它林产品提出了更高、更新的要求,要求各类用材实行定向培育,这是世界人工林发展出现的战略变化１）。杨树具有生长快、成材早、产量高和易于更新的特点,为最适的短轮伐期工业用材林经营树种（方升佐等,１９９３）。所谓定向培育,是指按最终用途所确定的对木材原料的要求,采用集约经营等科学管理措施,生产出种类、质量、规格都大致相同,价格具竞争力的大批木材原料。本文简要总结了南方地区杨树胶合板材定向培育技术中关于无性系选择、立地控制、密度控制、栽植材料选择及优化栽培模式等研究…     

Effect of wood species,digester conditions,and defibrator disc distance on wettability of fiberboard

Wettability of medium density fiberboard (MDF) surface affects paint or adhesive application and is, thus, of importance in the course of furniture manufacturing. This study investigated the effects of wood species, digester conditions and defibrator disc distance on the wettability properties. It was found that the wettability of the MDF significantly decreased with increasing the defibrator disc distance and increased with the increment in the severity of the digestion conditions. The highest wettability was found for samples made of beech wood having an average contact angle value of 74.5°, followed by poplar wood (76.5°), birch wood (79.7°), the mixture (1:1) of scots pine and beech wood (82.9°), and scots pine wood (86.4°), respectively.     

土地利用方式对湖泊洲滩湿地植物生物量的影响——以西洞庭湖国家级自然保护区为例

【目的】为了解土地利用方式对西洞庭湖洲滩湿地生态系统服务功能的影响,探索土壤含水率和物种丰富度在湿地恢复过程中所起的作用,进而为今后西洞庭湖湿地恢复工程提供指导。【方法】于2015年冬季通过收割法和生物量模型对杨树种植区域、退林还湿区域、天然洲滩这3个区域间的土壤含水率、物种丰富度和植物地上生物量差异及土壤含水率和物种丰富度与地上生物量相关性进行了初步探究。【结果】1)不同土地利用方式下洲滩土壤含水率与物种丰富度差异显著;天然洲滩土壤含水率最高,退林还湿区最低,杨树种植区和退林还湿区物种丰富度高于天然洲滩。2)不同土地利用方式下洲滩植被地上生物量差异显著;杨树林种植区的植物地上生物量高于天然洲滩,而退林还湿区与天然洲滩无差异;草本植物地上生物量呈现出天然洲滩区最高、杨树林种植区最低的规律。3)不同土地利用方式下土壤含水率与草本植物地上生物量呈正相关,物种丰富度与草本植物地上生物量呈负相关。【结论】利用和恢复工程对洲滩湿地土壤含水率和物种丰富度存在影响;土地利用方式对洲滩湿地生态系统功能存在影响;土壤含水率和物种丰富度对于修复退化湿地及生态系统功能具有重要意义。后续退林还湿工程开展可考虑人为增加土壤含水率以及移植苔草等优势物种等人工辅助措施,以促进退林还湿区域向天然洲滩湿地的演替。