季铵铜防腐木中有效成分的流失性试验

以季铵铜防腐剂处理南方松为原材料,参照美国AWPA E11-06标准,分析不同pH值、不同温度的水环境对季铵铜防腐木中有效成分流失率的影响。结果表明:铜和DDAC的总流失率在pH 9时的碱性环境明显小于其在酸性环境下的流失率,在pH 3时,分别达到最大值40.80%和44.43%;随着温度从室温(10℃)升高到30、50℃,铜和DDAC的流失率均明显增大;在14 d的流失时间里,铜和DDAC的流失率呈现出随时间递减的规律,并且DDAC比铜更容易流失到环境中。     

马尾松防腐处理材的干燥工艺

为了探索干燥质量优良、防腐荆流失率低的防腐木材干燥工艺,在70、80、90℃三种温度下,对速生马尾松防腐木进行干燥,并进行7和14 d的流失试验,分析干燥工艺与防腐剂流失率的关系.结果表明:随着干燥温度的升高,防腐剂的流失率增大;马尾松防腐木的最佳干燥温度为70℃.     

后干燥处理对防腐木材性能的影响初步研究

试验初步研究了后干燥处理对加铬砷酸铜(CCA-C)、季铵铜(ACQ-C和ACQ-D)三种防腐处理木材中铜的流失影响。结果表明:随着流失次数的增加,CCA-C、ACQ-C、ACQ-D三种防腐处理木材的铜流失量都呈降低趋势,最终降至非常低。随着处理温度的升高,3种防腐材的铜流失量都有所增大。CCA-C型木材防腐剂的抗流失性优于ACQ型木材防腐剂。在同等条件下,ACQ-D防腐材的铜流失率高于ACQ-C防腐材。     

含铜木材防腐剂的流失性能

依据AWPA E11-97标准,对不同配方含铜防腐剂的铜及三唑流失率进行了测定.结果表明,以氨水为配体的铜唑(CuAz)及ACQ制剂中,铜在木材中的固着率均高于乙醇胺,氨水有利于铜在木材中固着.乙醇胺为配体的CuAz及ACQ制荆中,低栽药量铜制剂的固着率均远高于高栽药量铜制剂.三唑制剂中含有铜,能降低戊唑醇的流失率,用乙醇作溶剂的戊唑醇的流失率相对较高,可达37%.     

CC及ACQ-B防腐剂处理木材的抗流失试验

对于氨溶性季铵铜ACQ-B处理的马尾松(Pinus massoniana)及尾叶桉(Eucalyptus urophylla)试材，在吸药量为3.0～6．0kg／m^2时，按标准AWPA M11-87测定的流失率小于2.50％。比较ACQ—B与CC两种处理材，当吸药量(以CuO计)相当时，CC的流失率较ACQ—B大。ACQ—B可用于与地接触的人工林木材处理，如农用材或建材。     

水载型木材防腐剂中有效成分固着的影响因素(续)

4 防腐剂保持量 在不同防腐剂浓度的处理材中,其化学成分的固着速率也存在着一定的差异.Cooper等[16]对规格为38mm×89mm×610mm的赤松板材分别使用1.7%、3.5%的CCA防腐剂处理后,置于相对湿度为95%、温度分别为21℃及60℃的固着条件下,实验结果表明:防腐剂浓度较高的处理材需要更长的固着时间,以使CCA各成分沉淀到木材中.Osborne等16也赞同上述观点,并且他们指出,在防腐剂成分固着不充分的处理材中,防腐剂中各成分在具有较高防腐剂保持量的试材中流失出去的要更多一些,而在固着比较充分的处理材中情况则正好相反,即:在较高防腐剂保持量的处理材中,防腐剂各成分的流失率反而要低.     

三种铜-季铵盐防腐剂的抗流失性及对木材材色的影响

研究了3种季铵盐与铜复配后的防腐剂的抗流失性和对木材材色的影响。结果表明：3种防腐剂均在较低温度下后续固着效果较好。后续固着温度为15℃，处理药液浓度为0.5%的条件下，FFJ－2的固着效果最好。但处理后对材色的影响较大。     

防腐后处理工艺对竹集成材耐久性的影响

以两种水载铜基防腐剂季铵铜和铜唑对竹集成材进行防腐处理,分析了不同药剂和载药量对竹集成材耐腐性能的影响,以及不同干燥温度对处理材抗流失性能的影响,以筛选适宜的竹集成材防腐后处理工艺,显著提高处理材的耐久性.结果表明,经防腐处理后,竹集成材的耐腐性能大幅度提高,当季铵铜载药量≥2.6 kg/m3或铜唑载药量≥1.3 kg/m3时,竹集成材可以达到强耐腐等级;处理材的铜固着率随着载药量的增加而提高,不同干燥温度对铜的抗流失性能影响不显著.总体上看,防腐后处理工艺能够满足提高竹集成材耐久性能的要求,但其防腐剂的抗流失性能有待提高.     

微蚀废液中铜回收工艺研究

为了选择性回收酸性微蚀废液中的金属铜,采用电沉积方法对影响该工艺过程的电流效率和阴极板上铜的沉积形态等因素进行了研究。实验结果表明此工艺回收铜的最佳工艺条件为:电解时间2 h,铜离子浓度18～26g.L-1,温度40～50℃,电流密度2.4～3.0 A.dm-2。在该工艺条件下阴极区产铜的形态主要以板状为主,电流效率最高达到96%以上。     

雨水冲刷对防腐处理折断杉木的防腐剂流失性能影响

用硫酸铜与二癸基二甲基氯化铵(DDAC)复配,对折断木进行顶端施药,模拟1～3年降雨量雨水对药剂主要活性成分流失的影响,检测木材中主要活性成份的载药量.结果表明:随取样深度增大,试样总载药量、DDAC与铜的含量都呈下降趋势;降雨量对试样中铜含量、DDAC含量、总载药量变化影响不显著.经5%浓度的防腐剂施药使腐朽菌不能在木材顶端1 cm内生长,并在2～3 cm 范围内减缓生长,在木材顶端形成防护层,可在3年以上时间内避免和减缓腐朽的发生,有效减少林农损失.5%药剂总成本约1元/株.     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

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。