低分子量三聚氰胺—甲醛树脂固定泡桐压缩木回弹的研究

采用不同浓度的低分子量水溶性三聚氰胺－甲醛树脂溶液浸渍泡桐木材，并对其进行压缩，结合表明；浓度为６％的ＭＦ树脂处理的泡桐压缩木在室温水中几无回弹，而用２５％的ＭＦ树脂处理的压缩木试样，即使在沸水中很少回弹。而且２５％ＭＦ树脂处理的试样在压缩率为５０％时，表面硬度可从０．１２２ＭＰａ增加到０．３６６ＭＰａ。     

低分子量MF树脂固定杨木压缩木回弹技术的初步研究

增加木材硬度和体积稳定性的方法主要包括化学改性、压缩处理和热处理。本研究使用不同浓度的水溶性低量三聚氰胺－甲醛（ＭＦ）树脂处理大青杨（Ｐｏｐｕｌｕｓ ｕｓｓｕｒｉｅｎｓｉｓ）木材，并在加热过程中作横纹方向的压缩处理，其实验结果表明：经低分子量ＭＦ树脂处理的木材试件，抗胀（缩）率（ＡＳＥ）为４７％，阻湿率（ＭＥＥ）为３６％；１０％树脂浓度处理的试件的室温条件浸水可完全保持其压缩变形；１７．５％和２５     

泡桐耐旱性与膜脂肪酸饱和度关系的研究

泡桐属树木在土壤水分胁迫下，复水可以降低膜脂肪酸饱和度，土壤水势从－２．０×１０５Ｐａ提高到－５．０×１０４Ｐａ，使叶片膜脂肪酸饱和度降低了２．０４％。敏感品种（南方泡桐，台湾泡桐）脂肪酸饱和度比耐旱品种（兰考泡桐，楸叶泡桐）低７．７４％，且油酸和硬脂酸含量存在较大差异。脂肪酸饱和度（ＤＳＦＡ）与叶片持水力成正相关，与电解质外渗率和水分饱和亏缺成负相关     

ＦＲ—１、ＦＲ—２及ＰＦ树脂对木材阻燃、防腐、尺寸稳定等效果的研究

功能性改良药剂ＦＲ－１、ＦＲ－２及ＰＦ树脂处理马尾松、毛白杨后对木材阻燃、防腐、尺寸稳定及ＭＯＥ／ＭＯＲ的研究结果表明，ＦＲ－１处理的马尾松吸药量为３４．５kg/m^3时，氧指数可达６１％。ＦＲ－１处理的马尾松、毛白杨达到阻燃标准时，其用药理根据板材的厚度进行了初步确定，剂量范围为３０－９０kg/m^3。ＦＲ－１及ＦＲ－２在达到阻燃用药量的同时，处理后的马尾松、毛白杨耐腐试验的重量损失率小于或按拉１０％。ＦＲ－１处理的马尾松、毛白杨、吸药量分别为７５．６及９３．５kg/m^3时，吸水至饱和时，木材抗湿胀率（antiswelling ef-ficacy,ASE)分别为３０％、４６％；ＰＦ树脂处理的马尾松、毛白杨 、吸药量分别为７９．０％、６３．８kg/m^3时，ＡＳＥ分别为４６．２％、４１．４％。各处理对抗弯弹性模具（ＭＯＥ）影响为，ＦＲ－１处理的马尾松，ＭＯＥ差异不明显，ＦＲ－１处理的毛白杨，ＭＯＥ增加幅度为６．１％，ＰＦ树脂处理的马尾松，毛白杨、ＭＯＥ增加幅度分别为１０．６％及１７．９％。ＦＲ－１处理的马尾松、毛白杨对抗弯强度（ＭＯＲ）影响不明显。     

落叶松木材的FRW阻燃处理技术

研究采用真空加压法、以新型木材阻燃剂ＦＲＷ对难以浸注处理的落叶松木材进行阻燃处理。结果表明，在压力为１．４ＭＰａ、加压时间为１８０ｍｉｎ、前后真空度均为０．０９８ＭＰａ、前真空时间为３０ｍｉｎ及后真空时间为１５ｍｉｎ的工艺条件下，能初步实现落叶松木材的有效处理。     

落叶松纸浆纤维分级技术及应用的研究

运用６００－ＥＸ型锥形除砂器，对落叶松硫酸盐浆中早、晚材纤维进行了分离。通过正交试验运用极差分析方法，得出了影响分离效果折因素大小次序为纸浆浓度、除砂器下出口径和进浆压力；最佳操作工艺条件为纸浆浓度０．２５％￣０．２２％，进浆压力０．５ＭＰａ、出渣口径为Φ１０．７４ｍｍ。分级前原浆中早材纤维含量为４３．２％；分级后早材浆中早材纤维为７８．７％，晚材浆中早材纤维为７．６６％。     

杨木单板连续式热压干燥的研究

本文以生长在苏北地区的美洲黑杨单板（名义厚度１．７ｍｍ）为试材,在连续式热压干燥机上进行了生产型试验研究,采用高温导热油为载热体,热板温度１９２℃,热板压力０．０９ＭＰａ（前段）至０．１８ＭＰａ（后段）。研究结果表明：采用高温连续式热压干燥的方式辅以适当的“呼吸”周期,可在２ｍｉｎ内将生材单板（初含水率１４９％）干至８％以下的终含水率。干单板基本平整、光滑,终含水率均匀,无撕裂。单板厚度干缩率平均５．３％,横纹干缩率４．９％。胶合强度平均０．８１２ＭＰａ略高于网带对流干燥的０．７７９ＭＰａ,结果说明此法干燥人工林场木单板是可行的。     

废纸刨花板制造工艺的初步研究

对废纸刨花板的制造工业进行了初步探讨,分析了废纸用量,施胶量,热压时间,热压温度４个变量因子对刨花板性能的影响。试验结果表明添加部分废纸制造刨花板是完全可行的,其产品主要物理力学性能,密度（ρ）０．７５ｇ／ｃｍ＾３,吸水厚度膨胀率（ＴＳ）３．８％,内结合强度（ＩＢ）０．６２ＭＰａ,静曲强度（ＭＯＲ）２２．４ＭＰａ弹性模量（ＭＯＥ）２５．４×１０＾３ＭＰａ均达到ＧＢ／Ｔ４８９７－９２中Ｂ类刨花板的技     

异氰酸酯胶在刨花板中的应用

异氰酸酯胶作为刨花板胶粘剂，具有刨花含水率适应范围广（０～２５％），施胶量低、无游离甲醛释放、适合制造轻质刨花板等优点。施胶量为５％、密度为０．４５ｇ／ｃｍ３和０．６１ｇ／ｃｍ￣３的二苯基甲烷二异氰酸酯（ＭＤＩ）小黑杨刨花板的物理力学性能分别达到Ａ类刨花板二等品和优等品的指标要求。密度为０．６５ｇ／ｃｍ￣３时，只要ＭＤＩ施胶量达到３％，刨花板的物理力学性能指标能达到Ａ类刨花板的国家标准要求。试验还表明：ＭＤＩ具有较好的耐水性，但耐湿热性和长期耐水性不如酚醛胶。生产１ｍ￣３刨花板ＭＤＩ与ＰＦ和ＵＦ胶粘剂成本比为２．０５：１．７８：１．００。     

高密度纤维板生产工艺的初步研究

采用正交试验法，对高密度纤维板产品密度、三聚氰胺甲醛树脂施加量、热压压力、热压温度４因素进行了试验，分析这些因素对产品性能的影响．结果表明：采用密度０．９ｇ／ｃｍ３，脲醛树脂与三聚氰胺甲醛树脂混合胶，总施胶量为木纤维质量的１０％，其中三聚氰胺甲醛树脂占总施胶量的５０％，压力５．０ＭＰａ，温度１８０℃的生产工艺，能生产出性能良好的高密度纤维板     

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.