杨小舟蛾羽化规律的研究初报

杨小舟蛾[Micromelalophatroglodyta(Graeser)]是杨树人工林主要食叶害虫之一，曾于1987年至1989年在我省西部的杨树人工林中大面积暴发成灾，造成严重的经济、生态损失。近年来其种群密度又呈上升趋势，极有可能在短期内暴发成灾。杨小舟蛾在我省一年2代，以蛹在地被物中越冬，成虫分别出现在5月上旬和7月中旬。研究成虫羽化规律对于预测预防及防治有其特殊重要意义。且试验环境与方法1989年《月下旬从林间采集大量的杨小舟蛾越冬蛹，模拟自然界生态条件选放在平均树高为4m、郁闭度为9．65、5年生杨树纯林的枯枝落叶层中，然后用铁纱网笼…     

气候因素对杨小舟蛾生长发育的影响

对杨小舟蛾在青岛地区的生活史和发生规律进行了研究。结果表明:杨小舟蛾在青岛1年4代,世代重叠。日平均气温的变化对越冬代杨小舟蛾成虫的日羽化量及杨小舟蛾卵、幼虫和蛹的生长发育产生直接影响,日平均气温15℃时杨小舟蛾成虫开始出现,23.6～28.9℃时成虫羽化数量明显增加;成虫羽化的适宜湿度为60%～82%,以78%为最适。潮湿多雨的气候不利于杨小舟蛾幼虫的生长发育,干旱高温天气极易导致其爆发成灾。赤眼蜂、寄生蝇、杨扇舟蛾颗粒体病毒是其重要的寄生性天敌,对其发生危害具有一定的控制作用。     

杨小舟蛾防治研究进展

杨小舟蛾是我国杨树人工林的重要食叶害虫,近年来在全国各地猖獗成灾,危害严重.笔者对其防治指标、监测预报和化学、物理、生物、营林、转基因抗虫等防治技术研究进展作了较为系统的综述,并提出该虫今后的研究方向和治理对策.     

杨小舟蛾综合管理技术研究

根据杨小舟蛾［Ｍｉｃｒｏｅｌａｌｏｐｈａ ｔｒｏｈｌｏｄｙｔａ（Ｇｒａｅｓｅｒ）］的生物学特性、发生规律、预测预报、防治指标及防治技术,提出了杨小舟蛾综合管理原则和防治策略,制定了综合管理工作规范,为生产应用提供了科学、系统、实用的杨小舟蛾综合管理技术,使生产单位的防治工作有章可循。     

杨小舟蛾防治指标研究

通过测定周至县分布最广、受杨小舟蛾［Ｍｉｃｒｏｍｅｌａｌｏｐｈａ ｔｒｏｇｌｏｄｙｔａ（Ｇｒａｅｓｅｒ）］危害最重的８年生１５号杨在不同失叶水平下的材积损失，确定了其经济防治阈值。在测定杨小舟蛾幼虫食叶量及对其发生规律和防治技术研究的基础上，结合当地实际，制定了杨小舟蛾各世代的防治指标，拟定了其综合防治策略。     

济南地区杨小舟蛾年发生世代及灾变规律探析

根据商河县2013—2022年杨小舟蛾Micromelalopha sieversi成虫灯诱监测结果,确认杨小舟蛾在山东商河1a发生4～5代,个别年份发生6代;越冬代成虫始见期多在3月下旬,末代成虫结束期多在10月中旬,越冬代至第4代成虫高峰期的集中日分别为5月3日、6月7日、7月13日、8月6日、9月2日;确认螟黄赤眼蜂Trichogramma chilonis寄生杨小舟蛾卵,愈腹茧蜂Phanerotoma sp.、螟蛉盘绒茧蜂Cotesia ruficrus寄生杨小舟蛾幼虫;鉴定并命名济南地区杨小舟蛾幼虫致死病毒为杨小舟蛾颗粒体病毒山东毒株（MisiGV-SD）。根据商河县2012—2022年杨小舟蛾发生面积、危害程度、幼虫密度、天敌种类、寄生控制率、成虫灯诱等调查监测结果,结合2011—2022年商河县气象监测资料,探索分析杨小舟蛾主要灾变原因与发生规律：（1）持续高温、干旱及长无雨期极利于幼虫生长发育;（2）低温、大风和强降水是显著降低第1代虫口密度的重要因素;（3）杨小舟蛾颗粒体病毒传播流行是控制成灾的关键因素;（4）7—8月降雨量基本决定全年发生态势;（5）黑卵蜂Telen...     

杨小舟蛾的生物学特性研究

杨小舟蛾是为害杨树人工林的主要食叶害虫。在河南漯河1年发生4～6代,以蛹越冬。4月上中旬越冬代蛹羽化,第2代出现世代重叠,第2、3、4代为成灾世代。本文详细记述了该虫的年生活史、发育历期和生活习性等。     

翻耕灭蛹防治杨小舟蛾的效果评价

<正> 杨树是石首市主要速生用材树种之一。1981年以来,在全市17个乡镇、办事处广泛栽植,造林面积近十万亩。近几年随着杨树面积的扩大,害虫的发生日趋严重。1987-1988年全市杨树,有一半以上被杨小舟蛾危害,严重的地方,受害株率达85-90%,单株虫口密度高达2317头,叶片全被吃光。严重的影响了杨树正常生长,给林业生产造成了巨大的经济损失。为了保证林业的稳步发展和林木的正常生长。笔者经过几年的观察,试验研究,在掌握杨小舟蛾生物学特性及危害规律的基础上,使用了人工物理防治,即“翻耕灭蛹防治杨小舟蛾”的方法,收到了明显的效果。     

杨树舟蛾类害虫的辨别与防治

杨树舟蛾类害虫包括杨扇舟蛾、杨小舟蛾、杨二尾蛾3种，共同危害杨树、柳树等，其幼虫繁殖快、数量多、分布广，严重时把树叶吃光，危害性大，毁灭性强，极易成灾，为我国园林重要食叶害虫之一。杨树舟蛾类害虫在我国分布范围广，发生世代多，从北至南年发生2～3代至8～9代不等，容易造成世代重叠，给防治工作造成很大困难。特别是近几年，河北省邢台地区发展杨树纯林较多，更有利于害虫繁殖和生长。为科学防控舟蛾类害虫，保护绿化成果，维护生态安全，力促生态发展，我们不但要正确识别，还要掌握其发生发展规律及危害特性，抓住防治的最好时机，把虫害降到最低，保证树木健康生长。     

球孢白僵菌防治杨树食叶害虫试验初探

杨小舟蛾是洞庭湖区近年主要杨树食叶害虫,1年发生7代,在5、6月份杨小舟蛾1、2代的1～2龄时施放白僵菌进行防治,施药4 d后虫体出现病理反应,5 d后开始死亡,7 d出现死亡高峰,10 d因药死亡率为55.4%.通过死亡虫体白僵菌孢子的自然散发或幼虫取食感染,对以后世代虫口基数有明显的抑制效果.     

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。