杨扇舟蛾幼虫发育起点温度和有效积温研究

杨扇舟蛾clostera anachoreta fabricius完成幼虫期发育阶段所需的有效积温数不变。在自然变温条件下,本文对其幼虫发育起点温度和有效积温进行了初步研究。结果表明,杨扇舟蛾幼虫发育起点温度和有效积温分别为7.38±0.9（℃）和338.13±17.38（日度）。     

苦参碱烟碱乳油防治杨扇舟蛾试验

杨扇舟蛾在安徽北部一般一年4代,以蛹在茧内过冬,越冬蛹一般5月份羽化出成虫,成虫羽化后不久交尾产卵.第一代幼虫6月份进入危害期,第二代幼虫7月份进入危害期,第三代幼虫8月份进入危害期,第四代幼虫9月份进入危害期,10月下旬老熟幼虫沿树干向下爬至地面寻找枯枝落叶吐丝缀叶化蛹越冬.随着杨树纯林面积的不断扩大,蒙城及周边地区杨扇舟蛾危害日显突出,杨树每年凶杨扇舟蛾危害,叶片被蚕食,光合作用降低,林木正常生长受到影响,林木生长量下降.为了有效控制杨扇舟蛾的危害,减少林农的经济损失,探索高效、低毒、低残留、无公害的防治技术,蒙城县森林病虫害防治检疫站在省业务部门的支持与指导下,进行了应用1.2%苦参碱烟碱乳油防治杨扇舟蛾试验.     

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。     

分月扇舟蛾颗粒体病毒对杨扇舟蛾幼虫的毒力测定

用分月扇舟蛾（Clostera anasstomosis）颗粒体病毒（Granulosis virus,简称GV）对杨扇舟蛾幼虫以胃毒方式进行生物测定.结果表明：GV对杨扇舟蛾幼虫感染后的死亡率与病毒浓度呈正相关;1.58＆#215;10 3、1.58＆#215;10 4、1.58＆#215;106、1.58＆#215;10 6、1.58＆#215;107、1.58＆#215;108和1.58＆#215;109 PIB ＆#183;mL-1等7种浓度GV接种分月扇舟蛾幼虫后死亡率分别为7.32％、22.85％、53.61％、67.44％、85.61％、93.19％和97.36％,致死中浓度为1.58＆#215;105 PIB ＆#183;mL-1;接种1.58＆#215;109、1.58＆#215;108、1.58＆#215;107、1.58＆#215;106和1.58＆#215;105 PIB ＆#183;mL-1等5种浓度感染幼虫,导致幼虫死亡率大于50％,幼虫致死中时分别为4.08、4.65、5.9、6.89和8.55d.     

榆掌舟蛾发生期观测及幼虫龄期测定

通过多年持续灯诱监测,确定榆掌舟蛾Phalera takasagoensis Matsumura成虫发生期:7月上中旬为始见期,8月上中旬为高峰期,9月上中旬为终见期。采用饲养观察和林间调查相结合的方法,首次明确榆掌舟蛾幼虫有5龄型、6龄型和5~6龄混合型3种类型,8月上旬前孵化、8月下旬前后老熟的幼虫多为6龄型或兼有混合型,偶有5龄型; 8月下旬以后孵化幼虫、9月中下旬及以后老熟的幼虫均为5龄型。6龄型1~6龄头壳平均宽0.50、0.88、1.41、2.05、2.96、4.66 mm,幼虫历期28.3~43 d,平均32.3 d,各龄分别为4.2、5.2、5.4、5.9、4.4、7.2 d;5龄型1~5龄头壳平均宽0.52、0.90、1.53、2.68、4.37 mm,幼虫历期23.9~70 d,平均30.9 d,各龄分别为4.1、5.0、5.5、6.2、10.1 d;5龄型末龄幼虫历期最长达40.1 d,可耐-2℃短时低温;幼虫最早8月下旬老熟,最晚可危害至11月下旬。     

苦豆草生物碱对分月扇舟蛾的取食、生长和繁殖的抑制作用

研究了苦豆草生物碱对分月扇舟蛾幼虫拒食、生长和繁殖的影响。在选择性取食时,2.5mg·mL-1苦豆草生物碱即对分月扇舟蛾幼虫具有强烈的拒食作用,拒食率达62%～86%,而在非选择性取食时,拒食率仅为20%～29%;在选择性取食时,虫龄越大,拒食率越大,非选择性取食则未见此趋势。苦豆草生物碱对分月扇舟蛾幼虫的生长具有明显的抑制作用,表现在取食生物碱处理的食物后体重、体重增加量、相对生长率均显著降低。用浓度为10mg·mL-1的苦豆草生物碱处理后第2天,分月扇舟蛾幼虫相对生长率比对照下降了39.8%。对食物的消耗和利用效率均显著下降;取食量和排粪量分别是对照的57.7%和57.4%,近似消化率升高,而食物转化率和利用率均下降。此外,苦豆草生物碱处理后成虫的产卵量明显低于对照。讨论了利用苦豆草这一荒漠植物防治森林害虫的意义和前景。     

虫害诱导的杨树化学物质对分月扇舟蛾生长发育的影响

诱导抗性作为一种新的植物抗性类型,在防御植食性昆虫的取食和产卵方面具有很大的潜力。该项研究在室内采用选择性方法,观察了分月扇舟蛾幼虫对不同处理的杨树叶的取食选择行为。用虫害叶喂食2～3龄幼虫48 h,测定其营养效应,分析了喂食虫害叶对分月扇舟蛾的幼虫发育历期、蛹重、羽化率等生长发育的影响。利用生化方法测定了杨树叶片虫害后营养物质和次生物质的变化。结果表明:虫害叶对分月扇舟蛾表现为忌避作用;机械损伤叶不影响对寄主的选择性。分月扇舟蛾取食虫害叶后幼虫的发育历期延长、蛹重增加、羽化率降低,可溶性糖含量下降,单宁和黄酮含量增加。     

杨扇舟蛾的防治

杨扇舟蛾又名白杨天社蛾、小叶杨天社蛾,属鳞翅目舟蛾科扁舟蛾属,是我国林木主要害虫之一。杨扇舟蛾是一种食叶性杨树害虫,取食树叶,严重影响杨树生长。该虫在澧县1年发生4代,对杨树危害很大。该虫以蛹在枯叶内、地被物、表土中越冬。翌年4月中旬开始羽化,4月下旬为羽化高峰期,5月上甸第一代幼虫开始出现,至9月第四代幼虫期到来。10月底化蛹越冬。杨树叶全展开时,即为危害盛期。     

分月扇舟蛾生物学特性及其综合防治

分月扇舟蛾在吉林敦化区一年一代，以三龄幼虫在落叶间吐丝作茧越冬。该虫有两个幼虫为害期，以五月下旬至六月上旬为害最为严重。初步查明，在敦化连续两年4、5月份干旱和特殊林分环境是发生分月扇舟蛾幼虫为害的主要原因。本文还提出了分月扇舟蛾的综合防治措施。     

颗粒体病毒大面积防治杨扇舟蛾试验

杨扇舟蛾颗粒体病毒(Ciosteva anachoreta C·V),只寄生杨扇舟蛾幼虫,在林地采集感病虫体或室内饲养幼虫接种病毒,获得病毒虫体,粉碎、粗提、稀释1000倍后喷洒。在7月上、中旬防治杨扇舟蛾幼虫,效果显著,达到84—90%该病毒在专性强传播快,致死率高,世代交替受益等特点。     

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.     

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.     

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.     

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.