太原市国槐尺蠖的发生特点与防治试验

从省工、省时、降低用药量、减少对环境污染等方面考虑,在国槐尺蠖幼虫孵化盛期采用40%久效磷乳油对树干基部注药是防治的最佳期,防治效果达97.8%;在国槐尺蠖的幼虫4龄-5龄时用Bt乳剂(细菌性生物杀虫剂)600倍液-800倍液常规喷雾,防治效果达95%以上.     

印楝素乳油对蜀柏毒蛾的防治效果研究

采用室内浸渍和室外喷雾的方法研究了不同浓度0.25%印楝素乳油对蜀柏毒蛾的防治效果。结果表明:室内药效测定600倍和900倍浓度处理36h之后幼虫的死亡率均达到100%,1 100倍溶液在48h后死亡率达到100%;林间喷药试验中,600倍液、900倍液、1 100倍液在72h后的幼虫死亡率分别为100%、90%和85%。因此,采用0.25%印楝素乳油防治蜀柏毒蛾,其浓度以900～1 100倍液为宜。     

天竺桂日本龟蜡蚧防治试验

2006年对永安市区行道树天竺桂上的日本龟蜡蚧采用树干基部注射及叶面喷雾防治试验,结果表明:注射防治法效果较差,不宜使用;而喷雾法4种可湿性粉剂均有较好效果,防治效果达75.6%~93.3%之间。从防治效果与成本两方面考虑,防治时应优先选用杀灭2 000倍液、删虫1 000倍液,其次是利克虱1 000倍液,最后是欧贝1 000倍液。防治时机应掌握在初孵若虫期进行。     

山核桃干腐病防治试验

选取14种药剂经室内单浓度粗选和多浓度梯度的进一步抑菌试验,80%乙蒜素乳油、800/0402抗菌剂和95%硫酸铜晶体3种杀菌剂农药对山核桃干腐病有较好的抑菌作用;经林间防治试验,3种药剂的200倍液在刮除病斑或在病斑上深划线后再进行喷雾防治都有较好效果.直接刮除病斑不喷药也能起到防治效果,但人为造成树体新的伤口,易再度引发病菌侵入,且防治效果不持久,生产上不提倡使用.     

利用无公害药剂防治柳毒蛾试验研究

利用生物制剂森得保可湿性粉剂树冠喷雾防治柳毒蛾幼虫,不污染环境,效果较明显.喷药后72小时,2000倍液、3000倍液、4000倍液三种不同浓度处理死亡率分别达98.3%、95%、92%.从经济有效角度考虑,生产中可应用推广森得保可湿性粉剂3000倍液防治.     

辽宁本溪地区女贞尺蠖生物学观察及防治试验

采用普查法和定点观测法研究本溪地区女贞尺蠖的分布、寄主、危害以及生活史,通过灯光诱捕和室内饲养喂药进行防治试验。结果显示:女贞尺蠖在本溪地区普遍发生,主要危害紫丁香、水曲柳等;该虫1 a发生1代,以2龄幼虫在土下越冬;用400 w黑光灯野外诱捕效果最好;室内筛选出高效杀虫剂敌百虫200倍液、氧化乐果800倍液和苦参碱600倍液,防治效果均达98%以上。     

不同浓度氯氰菊酯防治榆紫叶甲成虫药效试验

榆紫叶甲是黑龙江省榆树重要食叶害虫之一,榆树幼树及大树均受其危害。文章通过试验研究了3%高效氯氢菊酯微囊悬浮剂不同稀释浓度室内及野外对榆紫叶甲的杀虫药效,结果表明:高效氯氢菊酯微囊悬浮剂对榆紫叶甲具有较好的防治效果,300～800倍液防治效果无明显差异,1 000～1 500倍液,室内杀虫效果略高于野外。生产上推荐使用浓度为500～800倍液。     

商洛市油松阿扁叶蜂生活史观察及防治技术初探

初冬深翻林下土壤,可明显降低松阿扁叶蜂越冬虫密度,控制其危害。每年4月份成虫羽化出蛰期地面喷8%的绿色威雷300倍液,防效达92%以上;1~2龄幼虫期郁闭度大于0.7的林分采用DDV和林丹烟剂防治效果达85%以上。5月上中旬,树冠喷40%氧化乐果乳油1 200倍液、25%灭幼虫脲Ⅲ号胶悬剂1 500倍液、2.5%敌杀死乳油4 000倍液、3%高渗苯氧威4 000倍液、1.2%苦·烟乳油1 200倍液进行树冠喷药,其防效达92%以上,最高达96%。提出了油松幼林营造油松栎类混交林;中龄林适当增加林窗密度促进形成针阔混交林;大面积油松营造防虫林带的营林防治措施,以控制松阿扁叶蜂的危害。     

长鞘卷叶甲化学防治试验

选用7种化学杀虫剂对长鞘卷叶甲成虫进行室内毒力测定,筛选出50%甲好清乳油、40%乐果乳油和90%杀虫单可溶性粉剂等3种杀虫剂的毒力较好,并应用于林间对成虫的防治试验。试验结果表明,分别使用甲好清和乐果的800~1300倍液以及杀虫单的800倍液进行喷雾防治效果较好,用乐果和杀虫单的100倍液进行根灌防治效果较好,用甲好清和乐果的10倍液进行注干防治效果较好,可适当应用于林间防治。     

商州区核桃黄须球小蠹防治效果试验研究

商州区核桃黄须球小蠹危害及防治试验结果显示,核桃林地有虫株率83%~89%,株均虫口数41.9头(表1),危害严重;剪干枝防治效果为94.3%,铒枝诱杀虫卵效果为100%,树冠喷洒25%西维因600倍液、80%敌敌畏乳剂800倍液、50%杀螟松乳油1200倍液防治效果分别为85.2%、92.86%、87.48%,防治效果明显。     

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.     

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.     

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.     

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.