刨花形态对竹材自生胶合刨花板性能的影响

利用半纤维素酶/漆酶协同处理3种不同类型的竹刨花,热压制备竹材自生胶合刨花板,研究不同刨花形态对刨花板物理力学性能的影响.结果表明:刨花形态对竹材自生胶合刨花板主要物理力学性能有显著影响,3种刨花形态中,4～16目的细刨花性能最佳,16目以上碎刨花作为填料加到大刨花中有利于提高刨花板弹性模量,减小吸水厚度膨胀率.该结论为进一步研究刨花形态与竹材自生胶合刨花板物理力学性能的关系提供了理论基础.     

印度竹类资源现状及其加工利用新措施

印度是一个具有丰富竹子资源的国家,在竹子资源储量和竹子生物多样性方面仅次于中国,在世界排名第二。该文概述了印度竹资源及其对竹材加工利用历程及现状,并对印度竹产业发展趋势做了总结。     

不同物理吸附材料/竹质废料复合刨花板对甲醛气体的吸附性能及其吸声性能研究

以竹质废料加工的竹刨花和不同物理吸附材料制备了竹刨花基复合板材,研究了其对甲醛气体的吸附特性、吸声性能及物理力学性能。研究结果表明:竹刨花复合板材对气体甲醛有较好的吸附效果。竹刨花与活性炭复合而成的板材具有良好的吸声性能。同时,吸附材料与竹刨花复合后对板材的物理力学性能无不利影响,且还能改善板材的物理力学性能。因此,该研究为室内环境净化提供了一种新材料,而竹刨花来源于竹材废弃物,将其有效利用可缓解对木材的需求压力。     

国内外竹子化学利用及其研究概况

我国竹子资源十分丰富，用途广泛，主要用于建筑、交通运输、制浆造纸、农业、水利建设、工艺美术、家具及日常生活用品等方面。竹资源包括竹材、竹枝、竹叶、竹箨、竹笋、笋壳、竹果以及竹黄等竹产品和副产品。竹子的化学利用是发展竹资源综合利用的重要途径之一。现根据国内外竹子化学利用及研究概况，对我国开展竹子化学利用存在的问题和相应对策提点看法。1竹子的化学处理竹材作为一种建筑和工业原料，具有多方面的优点，但也存在一些缺陷，如易虫蛀、易病腐变质、吸水干裂、弯曲、畸形及耐火性差等。竹子的防蛀、防腐以及防水、防火除…     

云南主要的16种竹种之竹材结构及其造纸性能研究

通过对云南主要的16种竹子竹材的竹壁进行制片和离析,而获其竹材结构纤维形态特征,结合纤维数量特征以及造纸对纤维形态的要求,对此16种竹子竹材的造纸性能进行了综合分析和评价,其作为造纸材的竹种排序为:小叶龙竹、甜龙竹、麻竹、黄竹、昆明实心竹、金竹、马关大节竹、龙竹、牡竹、梨藤竹、箣竹、黄金间碧玉、沙罗单竹、筇竹、慈竹、中华大节竹,为云南竹材的合理利用提供了科学依据.     

竹材解剖学研究进展

竹材解剖学是竹资源高效高值化利用的重要基础,也是竹子科学研究中的热点和难点之一。文中综述了竹材解剖学的历史沿革,总结竹材组织、细胞和亚细胞尺度的结构特性、竹材解剖的分子基础以及化学组分微区分布和分子结构的研究现状,简要阐述了竹材细胞壁多壁层构造的复杂性,提出竹材解剖学的未来研究展望,对深入研究竹材细胞壁以及竹资源高效利用具有重要的参考价值。     

微波法制竹刨花活性炭的工艺研究

当前我国政府制订了保护生态、环境的政策 ,启动了天然林保护工程 ,使一些以木材为原料的活性炭生产受到很大的影响。为了解决木材长期供不应求的矛盾 ,近年来 ,中国竹材的工业化利用开始起步 ,主要生产竹材地板、胶合板和竹家具等。在竹材加工过程中 ,出现很多竹刨花、竹屑副产品 ,企业一般弃之作燃料 ,如果将竹刨花制成活性炭 ,不仅可以变废为宝 ,实现资源再利用 ,提高企业效益 ,还将缓解活性炭在国内外供不应求的局面 (张齐生 ,1 995 ;2 0 0 2 )。以磷酸作为活化剂的化学法有比传统的氯化锌法污染较轻、成本较低等优点 ,已经成为当今世界…     

竹子有性生殖及其多样性

主要从我国竹子开花现象、开花竹株形态、花期、花器构造、结实、竹子实生苗等方面对竹子有性生殖的多样性进行了评述,并探讨竹类资源有性生殖多样性利用存在的问题及对策,为我国竹类资源多样性开发利用提供依据。     

浙江省竹子产业发展现状与急需解决的问题

综述了“九五”期间浙江省竹子产业的发展现状，提出了覆盖早出笋用林开花衰败严重、竹产品精深加工不足、竹材竹笋加工机械化程度低等急需解决的问题。     

竹类杂交育种的研究

竹子生长快、成材早,一次造林可以长期砍伐利用。竹材是农业、建筑业和纤维工业的重要原材料。竹笋是上等菜蔬。发展竹子生产,有利于经济建设,当前对于发展农村商品经济,增加农民收入尤有意义。广东气候温暖,雨量充沛,适合竹类生长。为了培育生长快、材质好、适应性强、经济价值高的竹子新类型,我们利用竹子自然开花的时机,进行了杂交育种方面的研究,下面是研究工作的概况。一、竹子开花结实的生物学特性为了避免杂交工作的盲目性,我们首先进行了开花结实生物学特性的观察。(一)开花预兆和花期竹子开花是正常的生理现象,一般在开花前一年就有预兆,表现为生势减退,出笋量明显减少,笋期提前,出现变型枝叶,材质变脆。竹子一年四季均可开花,但多在2—6月分数批开放,同一批花芽的开花时间很集中,盛花只     

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.