小径木三角形剖分法及其剖分材干燥工艺

对东北林区生长的具有代表性的针、阔叶树种如落叶松、柞术小径木的制材方式及干燥工艺进行了研究。研究分析得出,采用三角形剖分法,结合高温、高湿、汽蒸干燥新工艺,可有效解决小径木在干燥中容易出现的问题。     

小径木大青杨锯材间歇加热干燥工艺的研究

采用常规干燥基准,对小径木大青杨锯材(1000mm×45mm×30mm)分别进行了间歇2h和间歇6h加热干燥试验。分析了干燥过程中锯材含水率的变化规律,讨论了锯材干燥后的质量及小径木大青杨的皱缩特性,并与连续加热干燥试验进行了对比。结果表明,小径木大青杨锯材采用间歇加热干燥工艺是可行的;间歇加热方式有利于提高锯材的干燥质量,减少锯材的皱缩程度,间歇时间越长,效果越明显。     

阔叶树小径材热压干燥工艺的研究

通过对荷木和米槠两种华南地区常用阔叶树小径材薄板材热压干燥工艺的研究，探讨热压干燥工艺参数对小径材板材干燥质量（包括密度，厚度压缩率，尺寸稳定性及部分力学性能）的影响，试验结果表明，热压干燥工艺可以大大改善小径材的物理力学性能。     

白桦小径木截片干燥技术的研究

白桦小径木目前被广泛应用于木制品的加工与制作，主要产品是立木地板块和工艺地板块，但它们的干燥问题迄今尚未得到根本解决。本文对白桦小径木截片的干燥工艺试验进行了初步总结和探讨。     

不同干燥条件下小径桦木材性指标的研究

对小径桦木在大气及干燥室等不同条件下干燥后的材性进行了测试，结果表明：不同干燥条件对小径桦木的材性有影响。室干材的尺寸稳定性、变形程度及力学性能均优于气干材；采用软干燥基准时，可改善小径木的尺寸稳定性和力学性能，从而提高干燥质量。从总体材性指标可见，小径木更适合室内干燥。     

白桦小径材干燥技术研究

白桦是内蒙古大兴安岭林区的重要树种，资源丰富，它硬度适中、质白、无脂无味、纹理细腻，是制作地板砖的优质原料。随着成过熟林的减少，采伐和供应的木材中小径木的比例日益增加，目前该林区的许多企业均是利用白桦小径木生产地板砖。小径材因为生产年限短，内含物多，板材多带有髓心或靠近髓心，由此产生的结构不均衡导致小径材在干燥过程中容易产生开裂和变形。因此与大径级木材相比，小径材难干燥。小径材的干燥问题是影响小径材开发利用的重要因素。本研究根据小径材干燥的特点，研究制定了连续变化的干燥基准。采用研制基准干燥的小…     

小径原木干燥工艺初探

本文是在桦木（Ｂｅｔｕｌａｐｌａｔｙｐｈｙｌｌａ）、刺槐（Ｒｏｂｉｎｉａｐｓｅｕｄｏａｃａｃｉａ）与水曲柳（Ｆｒａｘｉ－ｎｕｓｍａｎｄｓｈｕｒｉｃａ）等小径原木干燥可行性分析与干燥特性研究等工作的基础上，总结出了小径原木的干燥工艺过程。生产实践证明，该工艺过程对小径原木的干燥是可行的。     

小径木削片制方机的研制

小径木削片制方机的研制（１５００４０）东北林业大学邢力平，马岩，汤晓华，蔡立新，金维珠，张建华目前，国内制材是以传统的带锯制材为主，由于带锯制材加工小径原木生产率低，功耗大，经济效益差，致使用带锯锯割小径木的企业普遍亏损。所以，现在国内带锯的制材工艺...     

小径木的制材方法与工艺

为缓解今后一段时期内木材短缺的困难局面,合理的加工利用小径木,将是我国制材工业发展的必然趋势。小径木合理制材,主要立足于提高小径木锯材的出材率和小径木的利用率。为此,必须设计采用适于小径木加工的高效设备,如小型框锯机、铣锯机、铣方机、多片原锯机,制材削片联合机及加工原木联动线等新型机床,以提高效率和保证锯材质量,并在加工锯材的同时获得工艺木片。而小径木的合理利用,主要在于开发     

杉木小径材胶拼技术

杉木小径材胶拼技术以６－１２ｃｍ的衫木小径材为原料，通过制材、胶拼、干燥和加工等工艺，生产出较大规格的板方材，可代替杉木中、大径材用于家俱、建筑等行业。     

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.