杀虫灯诱杀松毛虫的试验

通过在鹤岗市红旗林场设点布灯诱杀落叶松毛虫试验,结果表明:双灯诱杀效果好于单灯,晴天、无风天诱杀效果好。最佳开灯时间为20:00至4:00;采用杀虫灯诱杀落叶松毛虫防治成本为60元.hm2,比化学药剂防治成本低50%。     

落叶松毛虫老熟幼虫烟剂防治试验

落叶松毛虫是我国东北林区的重要害虫,大发生时可将大片松林针叶吃光。在哈尔滨市阿城区进行了落叶松毛虫药剂防治试验,结果表明:使用烟碱·苦参碱烟剂防治落叶松毛虫6~7龄幼虫效果不佳;使用敌敌畏烟剂防治效果较好,以每667m~2用药量2~2.5kg为宜。     

三种无公害药剂对松毛虫防治效果的比较研究

为筛选兴城地区松毛虫的最佳防治药剂,试验前期以2016年兴城地区3~4龄松毛虫为研究对象,对白僵菌粉、Bt、25%灭幼脲悬浮剂3种无公害的药剂的防治效果进行了比较研究。结果表明:3种药剂对松毛虫均显示了较为理想的防治效果,达到了86.7%以上。其中25%灭幼脲悬浮剂防效最佳,持效性强;Bt的速效性较好、白僵菌粉具有一定的迟效性。2017年追加开展了兴城地区林间松毛虫大面积防治试验,结合施药后松毛虫的发生情况来看,3种药剂总体防效尚佳,25%灭幼脲悬浮剂最优,在大面积防治中可有针对性地对这些药剂进行单一或合并使用。     

不同药剂对阜新地区松毛虫的防效比较

为筛选阜新地区松毛虫的最佳防治药剂,以2016年阜新地区3~4龄松毛虫为防治对象,对白僵菌粉、苏云金杆菌、25%灭幼脲3号悬浮剂3种无公害药剂的防治效果进行了比较研究。结果表明,几种药剂对松毛虫均显示了较为理想的防治效果,达到了86.7%以上,其中25%灭幼脲3号悬浮剂防效最佳,持效性强;苏云金杆菌的速效性较好,白僵菌粉具有一定的迟效性。2017年在阜新地区林间开展的松毛虫大面积防治试验显示,3种药剂总体防效以25%灭幼脲3号悬浮剂最优。大面积防治可有针对性地对药剂进行单一或合并使用。     

落叶松毛虫趋重的原因及防治措施

通过分析落叶松毛虫趋重的原因,结合工作实际,从加强虫情预测预报、物理机械防治、以虫治虫、药剂防治、行政干预、封山育林、调整树种结构、营造混交林、低质林改造等多方面阐述了松毛虫综合防治的技术措施。     

拟除虫菊酯类毒笔树干涂环阻杀松毛虫试验初报

拟除虫菊酯类是一种新型化学农药。具有触杀速效、低毒、用量少、效果好、成本低等优点。为探索简便易行、经济有效的防治方法,达到把松毛虫消灭在上树为害之前的目的。我们根据北方松毛虫冬季在树下越冬的习性,将国产与进口的拟除虫菊酯类农药,制成药剂含量不同的毒笔,采取围绕树干涂毒环的方法,对落叶松毛虫、油松毛虫进行了上树前的阻杀试验,取得了明显的效果,现将试验结果整理如下。     

针阔混交林不同混交配比对落叶松毛虫数量的影响

研究分析落叶松纯林与落叶松-水曲柳混交林中落叶松毛虫的发病概率和发病程度,并对比了不同混交配比条件下落叶松毛虫的发病程度。结果表明,落叶松纯林中落叶松毛虫的发病率及发病程度明显高于落叶松-水曲柳混交林,单株落叶松上落叶松毛虫的个数比混交林平均高出1. 6倍,而在混交林中,不同混交配比对落叶松毛虫的发生数量也有明显影响,其中以3∶5比例进行混交的林分,单株落叶松上落叶松毛虫的个数最低。综上所述,采用混交的方式可以大幅度降低落叶松毛虫病害的发生和扩展,而3:5比例的混交方式是抑制落叶松毛虫病害扩散的最有效途径。     

松毛虫华丽寄蝇寄生落叶松毛虫的调查初报

通过对松毛虫华丽寄蝇寄生落叶松毛虫幼虫的调查结果看出，其自然寄生率达48．8％，是落叶松毛虫幼虫期的重要天敌种类，为进一步对其保护和利用提供科学依据。     

长白山地区落叶松毛虫生物学特性研究

对吉林省长白山地区落叶松毛虫(Dendrolimus superans Butler)的生物学特征进行了研究,结果表明:(1)落叶松毛虫在长白山地区1年1世代,跨2个年度,幼虫共7龄。(2)该地区落叶松毛虫产卵量随雌蛹质量增加而增加,线性回归关系为:y=109.17 x-95.185,R2=0.855 2。且当蛹质量小于2.00 g时,其产卵量较少,但当蛹质量高于3.50 g时,落叶松毛虫产卵量大幅增加,一般在300粒以上。据此可对翌年落叶松毛虫种群密度进行估算和监测。     

塑料薄膜围扎落叶松树干防治落叶松毛虫技术

落叶松毛虫是危害落叶松生长的主要害虫之一 ,随着三北防护林杨改松力度的加大 ,落叶松造林面积不断加大 ,对落叶松毛虫的防治任务也越来越重。采取化学方法防治 ,不仅成本高 ,而且还污染环境、杀伤天敌。采用塑料薄膜围扎落叶松树干防治落叶松毛虫 ,不但降低了防治成本 ,同时还延长了防治时间 ,保护了环境 ,保护了天敌 ,是一种非常理想的防治落叶松毛虫的好方法。　　用塑料薄膜围扎落叶松树干防治落叶松毛虫的原理 :　　落叶松毛虫有一个特殊的生活习性———就是在每年的 10月中旬左右从树上爬下 ,在树冠下的枯枝落叶层与地表处越过寒冷…     

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.