草履蚧可持续控制策略与技术

对草履蚧Drosicha corpulenta kuwana及其主要天敌－－红环瓢虫Rodlia Iimbata Motschulsky的生物学特性，发生规律，预测预报，防治指标，防治技术等方面进行了系统的研究基础上，总结出的以阻隔防治和保护利用红环瓢虫进行生物防治为主的草履蚧可持续控制技术，1999－2001年应用该技术在西安市的周至、户县等8县区防治草履蚧1．37万hm^2,3年内防治全部实现了可持续控制目标，经济，生态和社会效益十分显著。     

杨树害虫草履蚧的阻隔防治新技术

指出了2007~2015年,有关部门组织科技人员开展了草履蚧阻隔防治技术研究,探索出了在树干上涂敷黄泥层,然后在树干套铁皮套筒,及在铁皮套筒外表涂层杀虫药膏,从而阻隔草履蚧若虫上树的危害,及时把草履蚧若虫阻隔在树干下喷药杀灭。通过反复试验,总结出了使用寿命长、阻隔阻杀效果好、防效率效果显著的防治新技术。     

草履蚧的生物学特性及防治

草履蚧是杨树、法桐、核桃的主要害虫,在河北省邢台地区1年发生1代,以卵在寄主附近的土中越冬.翌年2月上旬至3月上旬,越冬卵孵化.4月下旬,雄虫羽化,和雌虫交配后死亡.雌虫5月下旬由树干爬到树根附近疏松的泥土中产卵,越冬卵至翌年2月～3月孵化.根据草履蚧发生规律,在防治上主要抓住若虫期,分别采用人工、阻隔及药物防治,     

草履蚧虫的危害及防治

草履蚧虫的危害及防治赵庚钧草履蚧虫是介壳虫类中的一种，分布于我国大部分地区，危害珊瑚树、杨树、悬铃木等树木，严重时可造成树木生长不良，早期落叶，甚至死亡。对草履蚧虫的防治不可忽视。一、草履蚧虫的形态识别草履蚧虫成虫有雌雄之分，雌虫无翅，扁平，椭圆形，...     

草履蚧壳虫阻隔效果的观察

草履蚧壳虫（Drosicha corpulenta kuwana），简称草履蚧，属同翅目蚧壳虫科，雌、雄异形，雌虫无翅，以卵越冬。原为果树花卉害虫，随着杨树面积的扩大，已成为杨树的主要害虫。一年发生一代，以若虫或雌成虫吸食林木枝条树液而生活，从而造成枝条干枯、林木生长不良，严重时整株死亡。由于若虫在温度适宜时每天24小时不间断地从土中上树，在时间上给喷药防治带来了困难。同时若虫上到树梢后，一般手压喷雾器无法喷洒到位，担架式高压喷雾器因受到多因素（如沟坝、农田、风向）的影响，防治效果也很不理想。2002—2003年我们在蒙城县小涧镇用透明胶带等不同材料对草履蚧进行阻隔试验，并对阻隔效果进行了观察。     

草履蚧防治技术研究

在观察了草履蚧的虫态、生活史的基础上，采用人工绑扎塑料薄膜阻隔若虫上树，油泥粘胶，喷洒氯氰菊脂、溴氰菊脂毒杀，夏季扫除虫卵和黑光灯诱杀雄虫防治试验。结果认为，以人工绑扎塑料薄膜阻隔若虫上树防治效果最佳     

草履蚧防治试验

草履蚧在连云港地区1 a发生1代,以卵在卵囊内于土中越冬,危害杨树等寄主26种.草履蚧的天敌有大红瓢虫和黑红缘瓢虫2种,以幼虫取食草履蚧若虫.防治试验结果表明,在2月上中旬若虫上树前在树干上缠胶带阻隔若虫上树,阻隔率98%以上;6月上中旬,于树干基部周围培松土诱集成虫产卵,防治率90%以上;用20%吡虫啉20倍液注射防治,杀虫效果在90%以上;在小树树干上用20%吡虫啉原液直接涂刷毒环,杀虫率在98%以上;分别用50%辛硫磷、50%敌敌畏、25%扑虱灵可湿性粉剂等各1 000 倍液及果树宝200倍液进行喷雾防治,施药后48 h(扑虱灵7 d),校正防效均在95%以上.     

红环瓢虫生物学特性观测及保护利用

红环瓢虫是草履蚧的重要天敌,整个世代经过卵、幼虫、蛹、成虫4个阶段,共4龄,以成虫越夏越冬,翌年2月下旬至3月上中旬开始出蛰,出蛰不整齐,3月上中旬至5月上旬为卵期,3月中下旬至5月下旬为幼虫期,5月中旬开始化蛹,5月下旬至翌年4月下旬为成虫期。红环瓢虫具有互相残杀的习性,对草履蚧有很强的抑制能力,能取食草履蚧的若虫、蛹和成虫,可利用红环瓢虫对草履蚧进行生物防治。     

草履蚧的发生与综合防治——以颐和园为例

草履蚧在我国分布广泛,是重要的林业有害生物,在颐和园内危害柳树、杨树、榆树、槲树、紫薇等园林植物,因园内柳树基数大,造成草履蚧对柳树的危害尤为突出。草履蚧常群集危害,若虫和雌成虫吸食树汁,树木受害后不能正常萌芽或萌芽后失水萎蔫,影响园林景观。为了保护皇家园林植物资源、提高颐和园植物景观与游览舒适度,草履蚧的防治工作迫在眉睫。经过多年观察草履蚧的生物学特性和在颐和园的危害规律,实践包括物理防治、化学防治和释放天敌昆虫等不同防控手段,总结出一套具有颐和园特色的草履蚧综合防治措施。在核心游览区、新东堤及六桥区域、团城湖水源保护地周边使用泥环法,既能有效阻隔害虫上树,又能保证外观统一整洁、副作用小。万寿山区域采用粘虫胶,达到防治效果的同时节省人力物力资源。当出现个别地点害虫爆发严重影响园林景观,采用化学药剂进行紧急救治。坚持在团城湖周围释放小蜂、瓢虫等天敌昆虫,并种植蜜源植物,促进群落稳定生存并发展,将草履蚧数量控制在可接受范围内。     

北方城市草履蚧暴发成因及综合防治技术

该文介绍了草履蚧的生物学特性,分析了草履蚧在城市园林绿化区域易大发生的成因,介绍了草履蚧的提前预防措施、物理防治措施、生物防治措施、化学防治措施等技术,对于防治草履蚧的蔓延和发展有积极的指导意义,有利于城市园林环境的改善和提高。     

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.     

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.     

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.     

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.     

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。