桉树同安钮夜蛾的防治研究

在室内采用浸渍法测定了几种农药对同安钮夜蛾卵和幼虫的毒杀作用,在室内外用不同类型的诱虫灯对其成虫进行诱捕试验,结果表明：抑大保或甲维盐2000倍液对卵的防治效果较好,达97.7%以上;除尽或甲维盐2000倍液对3-4龄幼虫的杀虫率均达100%;阿维菌素4000倍液和灭幼脲III2000倍液对5-6龄幼虫的杀虫率分别为96.7%和64.4%。同安钮夜蛾成虫基本上无趋光性。     

6种植物源农药对竹斑蛾幼虫的毒力及应用分析

为筛选有效控制竹斑蛾（Artona funeralis）幼虫的植物源农药,选用6种植物源农药开展室内毒力测定和林间防治效果分析。结果表明：6种植物源农药对竹斑蛾幼虫均有良好的致死作用。参试的植物源农药以1.2%烟碱·苦参碱乳油和1.5%苦参碱可溶液的毒力较强,0.4%蛇床子素乳油的毒力较弱;4%鱼藤酮乳油、1.2%烟碱·苦参碱乳油、0.4%蛇床子素乳油、1%苦皮藤素可溶液、碧绿1%苦参碱和1.5%苦参碱可溶液对竹斑蛾幼虫的LC₅₀分别为0.826 mg/L、0.596 mg/L、1.016 mg/L、0.962 mg/L、0.811 mg/L和0.612 mg/L;林间施药4 d后,6种植物源农药的防治效果均超过90%;最佳田间施药浓度为：1.5%苦参碱可溶液和1.2%烟碱·苦参碱乳油均为1 500倍液,碧绿1%苦参碱和4%鱼藤酮乳油均为1 200倍液,0.4%蛇床子素乳油和1%苦皮藤素可溶液均为1 000倍液。参试的植物源农药对竹斑蛾幼虫的防治效果良好,可用于生产上防治竹斑蛾幼虫。     

3种药剂防治白杨透翅蛾初孵幼虫试验

通过选用350g·L-1吡虫啉悬浮剂、30%甲维毒死蜱乳油和40%氧化乐果乳油3种药剂,每种药剂设2个浓度梯度,喷洒树干对白杨透翅蛾低龄幼虫开展防治试验。结果表明:施药后20d,6种处理无显著差异,防治效果均达到90%以上;3个药剂平均虫口减退率为97.29%。350g·L-1吡虫啉悬浮剂500倍液、30%甲维毒死蜱乳油800倍液和40%氧化乐果乳油1 000倍液可用于白杨透翅蛾低龄幼虫防治。     

虫线清乳油防治桉树枝瘿姬小蜂试验

用16%虫线清乳油2 g/L液和1 g/L液分别喷杀桉树苗上的枝瘿姬小蜂,20 d后桉树枝瘿姬小蜂的幼虫死亡率分别为40.8%和33.0%,成虫校正死亡率分别为97.2%和88.7%。对枝条和叶片上虫瘿内的幼虫死亡率检查结果表明,叶片上幼虫死亡率略高于枝条上幼虫死亡率,但两者差异不显著。     

柳蓝叶甲生物学特性观察及防治试验

通过野外采集柳蓝叶甲(Plagiodera versicolora)成虫进行室内饲养及野外生物学特性观察,并采用5种商品农药对室内饲养的成虫和幼虫进行了毒杀试验,结果表明,柳蓝叶甲在浙江丽水1a发生9代,以成虫在杂草丛、落叶层、土壤缝隙中越冬.翌年3月上旬出蛰活动,5月至10月为成、幼虫危害盛期,11月上旬开始越冬.室内农药试验表明,480 g/L毒死蜱乳油1000倍液对柳蓝叶甲成、幼虫都有很好的防治效果,死亡率可达100%;4.5%绿爽跳甲高效型微乳剂2 000倍液、1.8%阿维菌素乳油4 000倍液对柳蓝叶甲幼虫有较好的防治效果,死亡率分别为100%、89.3%,但对成虫防治效果不理想,害虫死亡率仅分别为44.9%、6.9%;20%氰戊菊酯乳油5 000倍液、3%啶虫脒微乳剂2000倍液对成、幼虫的防治效果均不理想.     

沙地新植榛苗蛴螬防治指标及防治措施

为研究不同虫口密度蛴螬对新植榛苗的危害及防治措施,进行了沙地新植榛苗蛴螬防治试验。在正常栽植条件下,以蛴螬3龄幼虫为试虫,采用人工接虫的方法,研究蛴螬虫口密度与新栽植榛苗死亡率之间的关系。结果表明:蛴螬的虫口密度与榛苗死亡率间存在极显著线性正相关关系(y=4.937x-4.502,r=0.989),二者相关性极显著。初步确定新植榛园蛴螬3龄幼虫的防治指标为每株3.949头。在试验区内对新植榛苗采用不同药剂灌根法防治,结果显示:采用稀释800倍液的4.5%毒死蜱乳油的防治效果最佳,可达85%。     

黄褐天幕毛虫4种生物农药药效比较及使用建议

为在黄褐天幕毛虫等鳞翅目食叶害虫防治生产中推广应用生物农药,开展好林木虫害无公害防治工作,以公路绿化林内山桃上发生的黄褐天幕毛虫为试验防治对象,以4.5%高效氯氰菊酯乳油2 000倍液和清水为对照,选用20亿PIB甘蓝夜蛾核型多角体病毒悬浮剂1 000倍液、8 000IU苏云金杆菌油悬浮剂600倍液、2 000 IU苜核·苏云菌悬浮剂750倍液和1%苦参碱水剂1 500倍液等4种生物农药,研究了4种生物农药对3龄前黄褐天幕毛虫幼虫的林间防治效果。结果表明:高效氯氰菊酯施药1 d后即效果显著,施药3 d后虫口减退率达到最高;4种生物农药虫口减退率均随施药后时间的延长而逐渐提高,虽然施药3 d后虫口减退率低于高效氯氰菊酯,但施药7 d后除2 000 IU苜核·苏云菌悬浮剂750倍液虫口减退率未达到90%以外,其他3种生物农药虫口减退率均在90%以上;施药10 d后4种生物农药虫口减退率全部高于高效氯氰菊酯,且均在90%以上,其中20亿PIB甘蓝夜蛾核型多角体病毒悬浮剂和苜核·苏云菌悬浮剂2种生物农药的虫口减退率超过95%,防治效果高出高效氯氰菊酯近7个百分点。除虫口减退率较高,生物农药对天敌影响较小,是一种环境友好型农药。     

2种不同施药方法防治大栗鳃金龟幼虫对比试验

用40%辛硫磷乳油、50%敌·辛乳油、甲氰菊酯乳油、1%苦参碱4种药剂的稀释液,在大栗鳃金龟幼虫距地表最近时,用根部追肥器在土壤中注射农药和用喷壶在草面上喷洒2种不同施药方式防治大栗鳃金龟3龄幼虫。结果表明:用根部追肥器在土壤中注射40%辛硫磷乳油400倍液和50%敌·辛乳油300倍液防治大栗鳃金龟幼虫效果分别达到95.87%和97.96%,比用表面喷洒农药的防治效果显著。     

5种生物农药喷雾防治竹镂舟蛾幼虫效果评价

为揭示无公害防控竹镂舟蛾的关键技术,在福建政和县选择竹镂舟蛾为害的毛竹林设立试验研究区,选用1.5%苦参碱可溶液、3%高渗苯氧威乳油、25%阿维·灭幼脲悬浮剂、1.2%烟碱·苦参碱乳油和1.8%阿维菌素乳油等5种生物农药,应用无人机喷雾技术,开展防治竹镂舟蛾幼虫用药的最佳使用剂量筛选试验,并检测竹林土壤和竹笋中的农药残留。结果显示：药后5 d,5种农药均有2个浓度水平对竹镂舟蛾幼虫的校正死亡率达86%以上;农药的最佳浓度水平(用纯净水以体积比稀释的倍数)是：1.5%苦参碱和1.2%烟碱·苦参碱均为1 500倍液,3%高渗苯氧威为2 500倍液,25%阿维·灭幼脲为1 000 倍液,1.8%阿维菌素为800倍液。在竹笋和土壤中均未检出所施的农药成分。研究结果表明,试验的5种农药对竹镂舟蛾幼虫致死作用强、防效好,且不会产生农药残留,竹林喷施这5种农药,可大幅降低竹镂舟蛾幼虫的虫口数量,达到无公害防控竹镂舟蛾成灾的目的。     

青海云杉苗圃地阿扁叶蜂发生规律和防控技术研究

为提高祁连山东段林区苗圃地青海云杉阿扁叶蜂的防治效果,笔者调查了青海云杉苗木受害程度,观察了阿扁叶蜂生活史,并研究了不同化学防控效果。结果表明:在祁连山东段林区青海云杉苗圃地阿扁叶蜂每2年发生1代。化学防控后,均降低了虫口密度、受害株率和苗木死亡率,与对照(CK)相比,差异均达到极显著水平(P0.01)。不同防控方法应用后虫口密度、受害株率和苗木死亡率由高到低的排序均为CK蛹期土壤拌药成虫羽化盛期地表喷药幼虫为害期树冠喷药。其中幼虫为害期树冠喷使80%敌敌畏乳油2 000倍液后,防效最佳,虫口密度、受害株率和苗木死亡分别下降到0.52头/株、1.47%和0.12%。     

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.     

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.     

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.     

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。     

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.