12种实木地板尺寸稳定性初探

文章对12种常用实木地板的尺寸稳定性进行研究,结果表明,柚木的尺寸稳定性最好,收缩率为0.33%,膨胀率为0.1%;水曲柳、桦木、纤皮玉蕊尺寸稳定性较差,收缩率均大于2.24%,膨胀率均大于0.35%;其余的8种地板稳定性相差不大,收缩率为1.09%～1.71%,膨胀率为0.16%～0.23%。成品实木地板尺寸变化较小且缓慢,在使用时做好水分处理就可以避免其严重变形。     

模似环境下6种地采暖用实木地板尺寸变化分析

对6种地采暖用实木地板在2种模拟室内环境下的尺寸变化过程进行分析,结果表明:亚花梨(Pterocarpus angolensis)、柚木(Tectona grandis)的稳定性优良,膨胀率分别为0.16%、0.19%,收缩率分别为0.60%,0.42%;印茄木(Intsia sp.)、橡木(Quercus sp.)和圆盘豆(Cylicodiscus sp.)的尺寸稳定性相差不大,膨胀率为0.25%~0.30%,收缩率为0.55%~0.75%;番龙眼(Pometia sp.)的尺寸稳定性最差,膨胀率最大,为0.49%,收缩率为0.66%。     

干燥方式对地采暖用实木地板尺寸稳定性的影响

以烘干法和压干法两种干燥方式处理的8种地采暖用实木地板为试验材料,与烘干法作对比,探究压干法对地采暖用实木地板尺寸稳定性的影响;通过木材水分吸湿特性分析压干法提高地采暖用实木地板尺寸稳定性机理。结果表明:采用压干法能明显提高地采暖用实木地板尺寸稳定性,但对径向耐湿尺寸稳定性改善不大。相比烘干法,采用压干法干燥的番龙眼、印茄、朴木、栎木4个树种的地采暖用实木地板径向收缩率分别降低53.8%、60.0%、47.1%、44.4%,轴向收缩率分别降低70.9%、55.6%、37.0%、37.5%,轴向膨胀率分别降低43.2%、31.8%、23.4%、16.5%。这与木材半纤维素的降解、分子链结构活性的增强和纤维素结晶度增加有关。     

刨花蒸汽处理提高刨花板的尺寸稳定性

本研究探索用高压饱和蒸汽处理刨花来提高刨花板的尺寸稳定性。分别对云杉(Picea spp。)和桦木(Betula spp。)找出了不同的蒸汽压力和处理时间与刨花板的弹性模量、静曲强度、平面抗拉强度和线性膨胀率之间的关系,并得出结论:蒸汽处理刨花时较适宜的工艺条件为:蒸汽压力1.3N/mm~2左右,蒸汽处理时间5～6min;经蒸汽处理后桦木刨花板尺寸稳定性的改善程度优于云杉刨花板。     

炭化杨木耐热、耐湿及导热稳定性能的研究

以速生杨木为研究对象,采用窑室常压热处理炭化工艺,研究炭化处理后杨木板材的耐热、耐湿尺寸稳定性以及导热性能方面的变化。结果表明,经过该工艺处理后,材料的耐热收缩率和耐湿膨胀率均下降,材料的尺寸稳定性均显著提高。炭化处理后,在湿胀稳定性方面,不同试材长度方向提高了6.67%~81.82%,宽度方向提高了27.47%~80.68%;在干缩稳定性方面,长度方向提高了21.32%~54.22%,宽度方向提高了62.34%~85.67%;材料的导热系数增加27.52%,导热性能显著提高。     

压缩-热处理联合改性对杨木尺寸稳定性的影响

为改善杨木质软、强度低的特点,同时提高其尺寸稳定性,首先对杨木试样进行压缩处理,再进行热处理,并检测压缩杨木和热处理压缩杨木的吸湿、吸水膨胀率.结果表明:压缩率愈大,压缩杨木试样厚度方向和体积膨胀率愈大;经热处理后,试样的尺寸稳定性明显提高.     

卫浴用树脂浸渍单板重组材的尺寸稳定性

为满足卫浴装饰装修用木材的需求,以速生桦木为原料,开发出一种树脂浸渍单板重组材。通过分析浸渍三聚氰胺-甲醛(MF)树脂固体含量、浸渍方法、热压压力等因子对板材尺寸稳定性的影响,结果表明:当MF树脂固体含量45%、热压压力1.0MPa,采用辊压浸渍(压榨率50%～70%)时,板材的极限体积膨胀率为6.2%,低于水曲柳、栎木等实木试件,尺寸稳定性大大改善。     

高温热处理对木材吸湿性和尺寸稳定性的影响

在4个不同温度和时间水平下,对人工林杉木木材进行高温热处理,研究了处理温度和时间对木材吸湿性和尺寸稳定性的影响规律。结果表明:高温热处理可以显著降低木材平衡含水率、吸水率和体积膨胀率,提高尺寸稳定性;随着处理温度的增加和处理时间的延长,杉木平衡含水率、吸水率和体积膨胀率降低;与处理时间相比,处理温度对平衡含水率、吸水率和体积膨胀率的影响程度更大。在本研究范围,与对照材相比,通过高温热处理可以使杉木平衡含水率降低17.73%~66.74%,吸水率降低33.99%~64.00%,体积膨胀率减少36.7%~69.30%。     

二羟甲基二羟乙基乙烯脲树脂处理对尾巨桉木材尺寸稳定性的影响

为提升人工林速生材的尺寸稳定性,以人工林尾巨桉（Eucalyptus urophylla×E. grandis）木材为研究对象,采用二羟甲基二羟乙基乙烯脲（DMDHEU）树脂进行真空-加压浸渍处理,分析树脂浓度和加压压力对木材增重率、密度的影响及增重率对木材尺寸稳定性的影响。结果表明,树脂浓度为30%、加压压力为1.2 MPa时,处理材增重率最大（23.85%）;各密度均最高,其中基本密度比未处理材高出26.9%,气干密度高出19.9%,全干密度高出19.8%;气干抗缩率、全干抗缩率、抗胀率和抗吸水率均最大,分别为72.9%、46.6%、53.5%和65.5%。木材增重率和密度均随树脂浓度和加压压力的增加而增加。树脂浓度高于20%、加压压力≥0.9 MPa时,木材增重率和密度增速均减缓。树脂浓度对木材增重率和密度的影响高于加压压力。树脂浓度相同、加压压力≥0.9 MPa时,木材增重率基本保持不变。相同压力下,处理材的尺寸稳定性随增重率增加而增加;压力≥0.9 MPa时,增重率达到9%～10%左右,木材抗胀（缩）率增速减缓。增重率相近、加压压力增加时,木材抗胀（缩）率有所增加,木材抗吸水...     

2012—2022年广西公益林森林生态系统服务价值评估

为科学评价广西公益林建设和保护成效，根据广西公益林森林资源连续监测数据，依据《森林生态系统服务功能评估规范》（GB/T 38582—2020），对广西2012、2017和2022年公益林的森林生态系统服务价值进行评估。结果表明，2012、2017和2022年，广西公益林森林生态系统服务价值以固碳释氧、涵养水源和生物多样性为主，占总服务价值的82.40%～83.95%；其次为保育土壤和净化大气环境，占15.13%～16.68%；林木养分固持服务价值最低，占0.89%～0.93%。天然阔叶林和灌木林生态系统服务价值较高，其次为松树（Pinus spp.）林、杉木（Cunninghamia lanceolata）林和竹林，桉树（Eucalyptus spp.）林和经济乔木林较低。天然阔叶林单位面积服务价值最高，其次为杉木林、松树林、桉树林和竹林，经济乔木林和灌木林较低。2012、2017和2022年广西公益林森林生态系统服务总价值分别为3 724.16亿元、3 856.49亿元和4 530.83亿元，单位面积服务价值分别为7.18万元/公顷、7.58万元/公顷和9.03万元/公顷。广西公益林...     

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.