The impact of mechanical log surface damage on chip size uniformity during debranching and debarking Eucalyptus pulpwood logs using a single-grip harvester

Mechanised harvesting operations are becoming more prevalent in South Africa with the realisation that motormanual and manual harvesting operations pose significant health and safety risks to workers. The damage inflicted by single-grip harvester feed rollers and delimbing knives on log surfaces during debranching and debarking eucalypts, may affect eventual chip quality. Chip quality influences pulp quality and recovery in the kraft pulping process. This study investigates the influence of two mechanised debranching and debarking treatments on Eucalyptus pulp logs (threeand five-feed roller passes along the stem surface) by feed rollers and delimbing knives on chip uniformity, size and purity. The two mechanised treatments to three log classes (base, middle and top logs) were compared with chips produced from manually debarked logs. Manually debarked logs produced significantly less undesirable-sized chips than both three and five-pass processed logs. The volume of undesirablesized chips produced during chipping also increased with decreasing log size. Manually debarked logs produced chips with significantly less bark than three-pass-processed logs (0.008% vs 0.062%), and five-pass-processed logs produced chips with significantly less bark than three-pass-processed logs (0.018% vs 0.062%). Middle logs also produced chips with significantly less bark than base logs (0.016% vs 0.056%), and top logs produced chips with significantly less bark than base logs (0.017% vs 0.056%). In all cases the bark content on logs was considerably less than the maximum of 1.0% generally specified by kraft pulp mills.     

Fibre losses during debranching and debarking of Eucalyptus pulp logs using a single-grip harvester

Mechanised harvesting operations are becoming more prevalent in South Africa, with the realisation that motor- manual and manual harvesting operations pose significant health and safety risks to workers. However, the potential damage caused by single-grip harvester feed rollers and delimbing knives on the log surface during debranching and debarking of eucalypts pulp logs may negatively affect fibre recovery as opposed to manually debarked logs, which show little or no log surface damage. Compared with manual debarking, this study investi- gated the influence of two mechanised debarking treatments on wood fibre loss on eucalypt log assortments debarked by harvester head feed rollers and delimbing knives. The two mechanised debarking treatments consisted of three and five feed roller passes along the stem surface. In addition to quantifying the magnitude of this fibre loss, a financial evaluation was done to calculate the value of these losses. The three- and five-pass debarking treatments caused significant fibre losses of 1.425 green tonnes per hectare (gt ha?1) and 2.275 gt ha?1, respec- tively, as opposed to manually debarked logs, which produced no fibre losses. Wood fibre losses in terms of total potential (or available) wood mass for three- and five-pass mechanically debarked trees were 1.06% and 1.70%, respectively. These represent a fibre value loss of R441.75 ha?1 and R705.25 ha?1 for three- and five-pass operations, respectively. For the 6.48 million gt y?1 currently mechanically debarked for the South African pulp and paper industry, this equates to fibre value losses of R21.36 million and R34.10 million annually for three- and five-pass operations, respectively.     

湘南丘陵地桉树纸浆林栽培模式研究

桉树已成为湖南湘南地区栽培的主要纸浆林树种。通过对桉树肥料、整地、密度等分析，得出湘南地区桉树集约经营的主要栽培模式：使用较耐寒的桉树品种(赤桉、邓恩桉、柳桉)的优良无性系或种源，15-20cm的容器苗，整地方式为人工带垦、中穴或机耕，每穴施放430g磷肥作为底肥，其间追施尿素65g、氯化钾肥25g，或追加氯化钾50g，或追加尿素130g，造林密度为1667-2505株/hm^2，轮伐期6-8年，栽植后要连续抚育3年，每年1-2次，主要是松土、扩穴、培蔸、施肥、控制杂草、防治病虫害。     

Rapid estimation of kraft pulp yield and lignin in Eucalyptus camaldulensis and Leucaena leucocephala by diffuse reflectance near-infrared spectroscopy (NIRS)

Near-infrared spectroscopy has been used to develop calibration models for the rapid determination of kraft pulp yield (KPY) and lignin in Eucalyptus camaldulensis and Leucaena leucocephala. The correlation coefficient for cross-validation is 0.90 for KPY and 0.95 for lignin prediction, while the root mean square error for cross-validation for KPY and lignin prediction are 1.46 and 0.77, respectively. The method has been validated with 37 samples of E. camaldulensis and 18 samples of L. leucocephala. The root mean square error of prediction for KPY (1.53) is higher than for lignin (0.77). The method is rapid and can be used for screening a large number of samples.     

循环干湿处理对尾巨桉木材含水率影响的研究

在大气湿度循环变化的过程中,木材含水率随之改变,导致木材胀缩性发生变化,引起家具零部件松动,甚至脱落和开裂。采用人工模拟大气湿度变化规律,对尾巨桉木材进行循环干湿处理,探索尾巨桉木材含水率的变化规律,旨在探索降低尾巨桉木材胀缩性的新途径,为尾巨桉木材干燥和实木加工提供新理论。     

35年生大花序桉生材性质研究

为研究大径级大花序桉人工林的基本木材性质,采用排水法对35年生大花序桉人工林木材的生材密度、基本密度、树皮率、心材率以及生材含水率等指标进行了测试。结果表明:35年生大花序桉的树皮体积百分率为8.92%,树皮质量百分率为12.35%,生材密度为1.12g·cm^-3,基本密度为0.76g·cm^-3,生材含水率为44.79%。各部位含水率差别不大,各指标表现都很好。     

四种桉树人工林木材气干特性研究

本文对柠檬按、巨按、尾巨按和窿缘按4种按树人工林木材进行气干特性和干燥规律的研究，预测它们在不同季节和不同含水率阶段的气干速度，并对气干质量进行分析，为有效利用其气干特性和规律合理地组织气干-窑干联合干燥提供理论依据。     

赤桉材干燥终了调湿处理中的流变行为

在实验室的小型调温调湿箱中对25 mm厚赤桉干燥材进行终了调湿处理,并以切片法分析调湿过程中的弹性应变和机械吸附应变特性.结果表明:经24 h的处理,表层的吸湿效果显著,含水率上升达5%,而板材的平均含水率上升2.5%～3.0%;表层压缩弹性应变在经历处理开始3 h内的短暂上升后迅速下降,而整个处理过程中心层的拉伸弹性应变变化不大;处理9 h后,次表层的压缩弹性应力比表层的大,产生反向的应力梯度;处理中,木材表层吸湿软化发生了补充收缩,缩小了内外各层长度差异,应力减小;表层软化有效地减小乃至消除机械吸附应变,但由于干燥历史的影响,机械吸附应变的变化滞后于含水率的变化,在处理的第3～9 h间下降幅度最大.     

应用电导法评价5个桉树抗寒性

文章从材料和条件控制上探讨电导法评价桉树抗寒性的应用,具体评价了4个桉树无性系和邓恩桉实生种的抗寒性.结果表明:EG-6无性系抗寒性较强,叶片半致死温度为-9.76～-8.95℃,井冈1号和广9次之,叶片半致死温度为-9.26～-8.22℃,邓恩桉和DH201-2较弱,叶片半致死温度为-8.80 ～-7.77℃.不同叶...     

尾叶桉纸浆林造林密度控制技术的研究

对 5 9年生尾叶桉纸浆林生长分析表明 :(1)密度与树高、胸径呈反比。 3种密度的树高、胸径大小均为密度B >C >D。两配置树高、胸径也以配置B >A。 (2 )密度对单株材积的影响与对胸径影响的规律一致。 5 9年生时单株材积生长量以密度B最高 ,达到 0 0 85 33m3·株 - 1,是最低单株材积密度D的 2 0 4倍。两配置单株材积以配置B >A。 (3) 4 7年生时单位面积蓄积量大小为密度B >C>D ,密度B达到 94 185m3·hm- 2 ,是最低D处理蓄积量的 1 15倍 ;5 9年生时蓄积量最大者为密度C ,达到 12 7 6 0m3·hm- 2 ,是最低蓄积密度D的 1 17倍。随着时间的变化 ,密度控制尤为重要。 4 7、5 9年生时单位面积蓄积均以配置B >A ,配置B分别比配置A高 2 4 82 %、2 3 5 3%。 (4)对胸径D和冠幅CW 值用方程进行回归拟合 ,结果以乘幂CW=a×Db 拟合最好。方程表达式为CW=0 4 72 4×D0 6 715。 (5 )编制的经营密度表反映出 ,随着胸径D的递增 ,基本经营密度N0 逐渐下降 ;当D≥ 18cm时 ,N0 的下降趋势渐趋平缓     

邓恩桉生材含水率、年轮宽度及木材密度研究

为了解邓恩桉的木材性质,本研究采用排水法和《GB/T 1930-2009》方法测定邓恩桉的生材含水率、年轮宽度以及木材密度。结果表明：全树生材含水率、年轮宽度、生材密度和基本密度均值分别为114.61%、4.73 mm、1.164 g·cm-3、0.522 g·cm-3。随着树高的增加,年轮宽度、木材密度呈-大-小-大‖趋势,生材含水率呈-小-大-小‖趋势;由髓心向外,木材密度逐渐减小,生材含水率逐渐增大,年轮宽度先增加后减小。4个材性指标在树干径向不同位置间差异极显著,在不同树高间差异不显著（除年轮宽度外）。基本密度与3个材性指标间存在极显著或显著相关。     

刚果12号桉W5无性系立木木材密度与含水率关系的初探

本文主要是对刚果12号桉w5无性系立木材密度与含水率的关系进行分析和探讨。分析结果表明两者相关程度达高度紧密程度,相关显著性达极显著水平,回归公式估测精度甚高,回归方程在本林区适用。     

闽西山地巨尾桉不同造林密度试验

试验表明选择适宜的立地条件,在1 665株.hm-2的造林密度下,采用2 m×3 m或1.7 m×3.5 m的株行距配置的林分生长最好,可获得较大出材量和经济效益,同时抗逆性较强。     

桉树枝瘿姬小蜂危害后桉树损失量测定

对桉树枝瘿姬小蜂危害后的桉树损失量进行测定,结果表明广林九号桉受害严重,巨桉受害相对较轻。对胸径、树高、树干、侧枝、叶片重量和叶片数量分别9n,4定,以叶片的损失率最大,广林九号桉的平均损失率分别达到30．8％,29．2％,60．0％,76．0％,98．4％和91．5％,巨桉的损失率分别达到9．1％,20．5％14．5％,20．6％,22．4％和20．9％。     

微波预处理对桉木化机浆性能的影响

通过微波、水浴两种加热方式下浸渍木片吸液量的比较,探究了微波对桉木渗透性的影响,结果显示:在其它浸渍条件(NaOH质量分数4%,木片质量分数20%)相同的情况下,木片浸渍时,经微波加热后其吸液量较水浴加热显著提高,微波处理5 min即可达到水浴处理45 min的吸液量,大大提高了浸渍效率。将微波用于化学机械法制浆的预浸渍阶段,经微波处理所得纸浆二段漂白白度最高可达68.9%(ISO),较汽蒸保温提高3～6个百分点;在加拿大游离度为305 mL时,微波处理浆的抗张指数可达19 N·m/g,撕裂指数可达2.15 mN·m^2/g,耐破指数达0.8 kPa·m^2/g,分别比汽蒸处理样高3 N·m/g、0.2 mN·m^2/g和0.1 kPa·m^2/g。     

粗皮桉木材力学性质的近红外光谱方法预测

以人工林粗皮桉木材为研究对象,采用常规力学测试方法和近红外光谱方法对其无疵小试样力学性质进行研究。用近红外光谱仪采集试样表面的近红外光谱,对采集的近红外漫反射光谱进行导数预处理并对不同波段光谱建立校正模型,以1/3试样作为预测集对校正模型进行验证。结果表明:二阶导数预处理、350～25000nm全光谱波段、径切面和弦切面平均光谱值对粗皮桉木材力学性质模型预测效果最好。抗弯弹性模量和抗弯强度、顺纹抗压强度的实测值与近红外光谱方法的预测值存在较好的相关性,相关系数均大于0.88,相对分析误差大于2.0,表明利用近红外光谱方法预测人工林粗皮桉木材力学性质效果较好。     

桉树杂种优势利用研究进展

原产澳大利亚的桃金娘科桉属树种,由618个种组成,其遗传学特点为:同一亚属的种可以互交产生杂种,无性繁殖较容易,是选择天然杂种,开展人工授粉杂交育种的极好原始材料,世界桉树主要种植国十分重视该项工作开展,我国自80年代起也广泛进行这方面的工作。     

江门市桉树发展现状及生态作用的探讨

针对江门市桉树快速发展现状及群众对有关桉树生态问题的种种猜测,笔者结合多年调查研究结果进行了系统分析。结果表明,桉树具有抑制大气CO2浓度上升,保持水土,高效利用养分与水分等生态作用,认为桉树是生态之树,致富之树,并对桉树人工林的经营提出了一些建议。     

大花序桉和火力楠木材物理力学性质比较

2014年以福建省漳州市龙海九龙岭国有林场12年生的大花序桉(Eucalyptus cloeziana)人工林为研究对象,并以乡土树种23年生的火力楠(Michelia macclurei)人工林为对照,对大花序桉和火力楠木材的物理性质和力学性质进行比较测定.结果 表明,大花序桉、火力楠的木材气干密度分别为0.78、0...     

云南省桉树生物量扩展因子(BEF)测定初探

通过对云南省不同区域桉树的典型取样,测定计算了桉树不同径阶的含水率、生物量和生物量扩展因子(BEF)。结果表明:桉树地上部分平均含水率为53.42%,低于云杉、云南松,高于桦木、木荷、栎类;桉树生物量扩展因子(BEF)平均值为1.23,小于云南省已经测定的5个树种的BEF值,小径阶桉树BEF值略大于大径阶BEF值。研究结果对于提升森林碳汇的精确计量具有积极作用。