苏北主栽树种对美国白蛾发生及幼虫生长的影响

调查了美国白蛾在江苏省北部地区近期的发生情况.选择苏北地区主要栽植行道及经济林木（杨树、泡桐、悬铃木、樱花及桑树）,研究树木种类对美国白蛾幼虫生长发育和存活的影响.结果表明,美国白蛾在苏北的发生及危害有加重的趋势.美国白蛾幼虫的体重、发育历期及存活率与所取食的树种有明显的相关性.悬铃木、杨树、桑树及樱花均为美国白蛾易感寄主.     

美国白蛾幼虫网幕林间分布规律调查初报

本文对美国白蛾第1代幼虫网幕林间分布规律进行了调查研究。结果发现,美国白蛾幼虫在多树种混合栽植的林分中,主要集中分布在喜食树种如桑、白蜡、榆、连翘、杨树等;林缘、散生木及路灯旁光线充足或厨房、厕所、猪圈周围也易发生。美国白蛾在四分行道树上单株树冠的不同方向均有分布,但主要集中在背离公路的一面;树冠中、下部幼虫网幕分布量占86.9％,树冠顶梢、上部仅占13.1％。     

本溪县园林树木主要虫害及综合防治

以本溪县园林树木为调查对象,调查了重要乔木的主要害虫种类及为害树种和主要为害期,提出了积极有效的综合防治原则及措施,以提高园林树木虫害的防治水平,把虫害对园林树木的损害减小到最低限度,从而充分发挥园林树木的绿化功能和环保功能.     

邯郸市飞机喷药防治美国白蛾作业及效果初报

美国白蛾幼虫食性杂,几乎涵盖邯郸市主要阔叶造林树种和园林树种,对园林树木、经济林、农田防护林等造成严重的危害,全市13个县(区)均有不同程度的发生。为了有效控制美国白蛾危害,2013年邯郸市首次实施了飞机喷药防治作业,作业后的调查结果显示,飞防有防效高、成本低、并能在短时期内压低虫口、迅速控制危害等优点。     

白蜡树病虫害发生规律及绿色防控技术

白蜡树广泛种植于我国的滨海盐碱地，是绿化和造林的重要树种。在白蜡树的种植过程中，病虫害威胁着树木生长，常见的白蜡树害虫主要为美国白蛾、云斑天牛等，如果应用传统的化学防治方案进行防治，不仅整体效果不佳，同时对生态环境形成较大的负面影响。针对白蜡树的病虫害发生规律及相应的绿色防治技术进行了探讨。     

白蛾蜡蝉为害树种及其天敌的调查

白蛾蜡蝉(Lawana imatata Melichar.)是热带、南亚热带的一种重要害虫,属同翅目蛾蜡蝉科。1980年以来,我们对该虫进行了观察,特别是对它所为害的树种及其天敌进行了一些调查,现报告如下: 一、为害情况白蛾蜡蝉为害树木时,其成虫和若虫密集在枝条和嫩梢上吸取汁液,影响枝梢生长,重者枝条枯干;为害果树时则引起落果或果实品质变劣。分泌的白色蜡质排泄物可     

美国白蛾研究初报

<正> 美国白蛾(Hyphantria Cuned Drury)属鳞翅目灯蛾科,是一种杂食性害虫,为害多种树木、果树和杂草,是一种危险性检疫害虫。一、分布及危害分布:美国白蛾原分布在北美大陆,主要分布在美国洛基山脉以东的广大地区;在加拿大只分布在与美国交界的部分地区;在墨西哥只分布在洛基山脉以东的墨西哥湾沿岸地区。1940年传入欧洲,首先在匈牙利首都布达     

欧黑抗虫杨N12对美国白蛾的抗虫性研究

通过美国白蛾的选食试验和迫食试验,对欧黑抗虫杨N12的抗虫性能进行研究,其结果表明:美国白蛾对不同杨树品种叶片的取食情况不同。在选食试验中,抗虫杨N12较其它树种有较为显著的差异;美国白蛾的抗虫性强弱依次为欧黑抗虫杨N12、中绥12、欧美107、意大利214杨、欧美108、荷兰64和辽宁杨。对比栽培区虫口密度,欧黑抗虫杨N12的感虫几率较其它速生杨低。     

严控美国白蛾在园林植物上蔓延危害

美国白蛾是我国重要的对内、对外检疫对象。它的食性杂,不仅危害园林植物,还危害林果树木、蔬菜花卉,对绿色植物叶片有毁灭性危害。该文从美国白蛾的分布及危害、形态特征、生活史及习性、综合防治等几个方面探讨了美国白蛾的防控措施,探索更优化的防治手段,保护绿化成果。     

美国白蛾的发生特点及防控措施

美国白蛾（Hlyphantria cunea（Drury））是一种对林木、农作物为害严重的害虫。本文针对滦县美国白蛾为害,从其生物学特性、为害特点等方面对美国白蛾现状进行简要分析,提出有效的预防、防治措施,以期对美国白蛾防治起到指导性的作用。     

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.     

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。     

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.