豚草卷蛾调查研究初报

豚草是从北美传入我国的恶性杂草，传播广，繁殖快，严重影响了农业生产和危害人类的健康，目前对豚草的防治主要用化学除草除和连根拔除的方法，对豚草生物防治鲜见研究，据调查，江西首次发现豚草卷蛾能使豚草枯心，萎蔫，枯顶，这对用生物方法控制豚草蔓延了有重要作用。     

利用性引诱剂防治松瘿小卷蛾

利用性引诱剂防治松瘿小卷蛾文／尹宁性引诱剂是利用化学方法合成的具有松瘿小卷蛾释放的雌性激素气味的化学物质。利用它可引诱松瘿小卷蛾雄性成虫前来交尾，以此进行粘着捕杀。松瘿小卷蛾，属鳞翅目卷蛾科，一年发生一代，以老熟幼虫在被害落叶松枝干部位孔穴内越冬，翌...     

塞罕坝地区落叶松线小卷蛾、松线小卷蛾的识别与发生规律

报道了塞罕坝地区落叶松线小卷蛾、松线小卷蛾成虫、幼虫和蛹的主要形态特征区别;两种线小卷蛾1 a发生1代,以卵在树皮内或老球果内越冬,4月下旬至6月中旬为幼虫危害期,老熟幼虫在枯落层内化蛹。两种线小卷蛾的发生数量受海拔高度影响较大。     

贺兰山异色卷蛾生物学特性及防治

异色卷蛾在贺兰山区地一年1代，以初龄幼虫在叶肉中越冬，翌年5月中下旬越冬幼虫开始活动，危害青海云杉梢顶芽及幼虫。采用喷雾，放烟和喷烟3种不同方式进行防治试验，筛选出最佳防治措施是释放敌马烟剂，平均防治效果达80％以上。     

槐小卷蛾初步研究

主要研究了槐小卷蛾Cydia trasias(Meyrick)越冬幼虫分布规律,提出了防治建议,调查表明,槐小卷蛾的幼虫主要在果荚中越冬,少部分在树干的翘皮裂缝中越冬。果荚受害率在18.8%—71.3%之间,树干上的越冬幼虫多在树干0.5米以下的缝隙中。形态观察表明,越冬幼虫腹部背面有一对肾形黑斑者为雄性,可用来统计雌雄性别。建议抓住越冬代防治,打落掉有虫果荚集中深埋;利用性引诱剂诱杀;成虫产卵期进行树冠喷药。     

枣镰翅小卷蛾性诱防治效果简介

枣镰翅小卷蛾(亦叫枣粘虫),属鳞翅目卷蛾科。据调查,该虫在我县一年发生3代,以蛹在树皮裂缝及树干伤口等处越冬。越冬代成虫子3月下旬开始出现,每雌产卵120～200粒。第一代幼虫大量出现期在谷雨前后,为害达两个月之久;第三代从7月上旬到9月上旬,为害约两个月。老熟幼虫潜入树皮裂缝或枝条裂痕处越冬。该虫食性单一,以幼虫为害枣树叶、花和果实,是枣树主要害虫之一。     

豫北地区李树6种卷叶小蛾危害观察与防治

河南省北部地区，由于李树栽培面积的迅速扩大及栽植方式的不合理，致使病虫尤其是卷叶小蛾的危害日益加重。据调查，一般李园病虫危害率达10％－20％，严重的达30％－40％，其中卷叶小蛾危害种类达26种以上，给李树生产带来一定的影响。文内深入地论述了6种卷叶小蛾的幼虫形态特征和危害特点，越冬方式和发生代数，同时，提出了简单、有效的人工和化学防治方法。     

松实小卷蛾在云南生活史及其对思茅松的危害

松实小卷蛾Retinia cristata Walsingham在云南危害思茅松是个新发现。2001-2003年对其生活史进行了观察。松实小卷蛾在思茅地区1a发生3代，以幼虫在受害梢中越冬。该虫主要危害2～3a生幼林，同一株树以向阳面受害最重，受害枝梢的直径范围为4．7～13．0mm。     

马尾松林油松球果小卷蛾发生及防治

油松球果小卷蛾钻蛀马尾松雌球花，２年生球果和嫩梢。该虫在浙江省一年发生１代，以蛹在土内越冬。本文报道了成虫的羽化规律，幼虫钻蛀及转移习性。该虫各虫态发生期与松实小卷蛾，芽梢斑螟等钻蛀性害虫发生的相关性；马尾松林中油松球果小卷蛾与松实小卷蛾的种群比率。通过试验，提出马尾松种子园４月中旬喷洒２０％杀灭菊酯乳油１５００倍液，防治效果达９０％以上。     

兴安落叶松鞘蛾脂肪含量对越冬后虫口基数的影响

对兴安落叶松鞘蛾越冬前后幼虫脂肪含量进行了测定，试图找出越冬前幼虫营养条件与脂肪含量的关系以及越冬前脂肪含量对越冬后的幼虫基数影响。     

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.     

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。