苦豆碱对松材线虫的杀线活性

研究了苦豆草中苦豆碱对松材线虫的杀线活性，讨论了苦豆草生物碱在研究防治松材线虫病中的意义。使用含苦豆碱的培养基培养灰葡萄抱菌菌丝的生物测定方法，测定了苦豆碱对松材线虫的杀线活性，５天后培养基中苦豆碱的ＬＣ５０＝２．６３×１０－５ｇ／ｍｌ，当浓度为１×１０－４ｇ／ｍｌ和２．６３×１０－５ｇ／ｍｌ时，１５天后苦豆碱的杀线率分别为９９．９％和９４．３％。     

芽枝状枝孢霉和螨蚧轮枝菌防治湿地松粉蚧研究初报

用芽枝状枝孢霉Ｃｌａｄｏｓｐｏｒｉｕｍ ｃｌａｄｏｓｐｏｒｉｏｉｄｅｓ（Ｆｒｅｓ）Ｄｅｒｒｕｅｓ和蜡蚧轮枝菌Ｖｅｒｔｉｃｉｌｌｉｕｍ ｌｅｃａｎｉｉ的孢子液２．５×１０＾７０／ｍｌ和０１．７×１０＾７／ｍｌ防治湿地松粉蚧Ｏｒａｃｅｌｌａａｃｕｌａ（Ｌｏｂｄｅｌｌ），试验结果为：在室内，用芽枝状枝孢霉的校正死亡率分别为８２．７％和８５．０％，用蜡蚧轮板菌的校正死亡率分别为８６．７％和６５．９％；林地     

苏云金杆菌和白僵菌对云南松毛虫的生物活性测定

将不同的苏云金杆菌菌株Ｂｔ１．Ｂｔ２、Ｂｔ３及白僵菌菌株５ＳＯ３、ＬＳ、ＧＤ，配制成不同浓度的悬浮液，饲喂感染３龄云南松毛虫幼虫。实验结果表明：生物活性较强的菌株有Ｂｔ２及５ＳＯ３，其感染浓度与死亡率值回归方程式为Ｙ（Ｂｔ２）＝－３．８１６２＋１．１６６５ｘ；Ｙ（５ＳＯ３）＝－２．３２７４＋１．００６２ｘ。致死中浓度ＬＯ＿（５０）为３．６１４×１０￣７细菌／ｍｌ和１．９１７×１０￣７孢子／ｍｌ；致死中时间ＬＴ＿（５０）分别为２．６４１天和７．６１９天。     

应用稀土抑制早竹开花的初步研究

用１０ｍｇＲＥＯ／ｍｌ和５ｍｇＲＥＯ／ｍｌ的稀土ＩＲＥ０３９１溶液在早竹珙花初期对其进行喷洒，能明显促进地径增长，抑制生殖生长，尤以５ｍｇＲＥＯ／ｍｌ的稀土溶液效果更显著。重复喷洒两次后，早竹可停止开花，恢复长势。但稀土对开花早竹出笋成竹数增加的促进作用较小。     

应用稀土抑制早竹开花的初步研究

用１０ｍｇＲＥＯ／ｍｌ和５ｍｇＲＥＯ／ｍｌ的稀土ＩＲＥ０３９１溶液在早竹开花初期对其进行喷洒，能明显促进地径增长，抑制生殖生长，尤以５ｍｇＲＥＯ／ｍｌ的稀土溶液效果更显著。重复喷洒两次后，早竹可停止开花，恢复长势。但稀土对开花早竹出笋成竹数增加的促进作用较小。     

Pt菌根剂在落叶松,樟子松造林中的试验

应用Ｐｔ菌根剂１ｍｌ／株，２ｍｌ／株，５ｍｌ／株三种不同剂量分别在落叶松，公造林上试验，３年后观测结果表明，落叶松地径，苗高，当年高生长分别比对照提高１５．００％，３０．１２％，４１．１０％，樟子松地径，苗高，当年高生长分别比对照提高２６．７２％，２５．９８，２８．６２％。     

应用ABT增产灵刺激毛竹林增产试验

采用ＡＢＴ５号增产灵１０ｍｇ／ｋｇ，每株３０ｍｌ处理当年发笋母竹，能增加笋、竹产量。浇蔸施药用药省，施药时期以１０月效果最佳，新竹增长１６．２０％－２７．３８Ｔ，株产笋平均增产０．７ｋｇ，产笋率提高７２．５％。     

稀酸协同D72树脂固定床催化莰烯水合反应

采用浓度为０．２％、０．５％、０．８％Ｈ２ＳＯ４及５％、１０％Ｈ３ＰＯ４协同Ｄ７２阳离子交换树脂固定床连续循环催化莰烯水合反应，反应２０ｈ，莰烯转化率９８％，异龙脑含量高达９３％，水合莰烯含量为１．２％．     

两种菊酯对马尾松毛虫的毒力测定与林间防治试验

用点滴法测定５％来福灵乳油和２０％杀灭菊酯乳油对马尾松毛虫幼虫的毒力，同时进行林间药效验证。点滴法测定毒力与林间药效结果一致，５％来福灵乳油的毒力和药效均高于２０％杀灭菊酯乳油，５％来福灵乳油防治马尾松毛虫使用剂量为每亩１，５－２．０ｍｌ．     

两种菊酯对马尾松毛虫的毒力测定与林间防治试验

用点滴法测定５％来福灵乳油和２０％杀灭菊酯乳油对马尾松毛虫幼虫的毒力，同时进行林间药效验证。点滴法测定毒力与林间药效结果一致。５％来福灵乳油的毒力和药效均高于２０％杀灭菊酯乳油，５％来福灵乳油防治马尾公毛虫使用剂量为每亩１．５－２．０ｍｌ。     

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.     

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.     

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.     

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。     

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.