滇柏球果螟生物学特性研究

对滇柏球果螟的形态特性进行了描述,对其生物学特性进行了观察分析：滇柏球果螟在昆明地区1年发生2代,以末龄幼虫在被害球果中越冬。幼虫2月上旬化蛹,3月开始羽化为成虫。3月下旬第1代幼虫开始蛀果危害,6月下旬至7月上旬幼虫老熟,在被害球果内结茧化蛹。第1代成虫7月中旬初开始羽化,第2代幼虫8月中旬继续危害球果,至11月后以老熟幼虫越冬。     

大灰象的生物学特性及防治方法的研究

大灰象Sympiezomias velatus（Chevrolat）食性很杂,在宁夏固原市六盘山林区苗圃地主要危害青海云杉幼树,在该地区2年发生1代,6月上旬幼虫孵出后取食须根及根皮,9月下旬幼虫做土室越冬,翌年4月上旬春暖后继续取食,至6月上旬开始化蛹,7月中旬羽化为成虫,并在原处越冬,4月中、下旬越冬成虫开始出土活动,群集取食苗眼和幼嫩的针叶,并进行交尾,5月下旬成虫在地下土壤中产卵.本次研究在摸清了大灰象生物学特性的基础上,最后结合大量防治试验结果提出了防治方法.     

中国宽尾凤蝶的生物学特性研究

通过野外调查结合室内饲养,研究宽尾凤蝶(Agehana elwesi)的生物学特性和生态学特性.中国宽尾凤蝶在浙江龙泉1年发生2代,也有个别1年1代.以蛹越冬,翌年5月上旬至6月上旬陆续羽化,产卵于寄主嫩叶正面,5月中旬开始孵化第1代幼虫,一直到7月上旬.6月下旬幼虫开始化蛹,7月上旬成虫开始羽化,一直延续至8月下旬....     

白杨叶甲生物学特性观察及防治

白杨叶甲在河北省平泉县1a发生2代,以成虫在枯枝落叶下和表土内越冬,4月中旬杨树发芽时开始上树取食危害,4月下旬开始产卵,5月上旬卵孵化为幼虫,6月初开始化蛹,6月10日左右出现第1代成虫。6月下旬出现第2代卵,7月上旬出现第2代幼虫,7月下旬出现第2代蛹,8月上旬出现第2代成虫,9月下旬成虫下树越冬。     

榆近脉三节叶蜂生物学研究初报

榆近脉三节叶蜂(Aproceros leucopoda Takeuchi)属河北分布新纪录种.在河北承德1a发生4代,以老熟幼虫在树下土壤中越冬,翌年4月中旬开始化蛹,4月下旬成虫羽化产卵,5月上旬幼虫开始孵化危害,后3代成虫期分别在5月下旬至6月中旬、6月下旬至7月中旬、7月下旬至8月中下旬出现.幼虫危害多种榆树,以...     

桉树油桐尺蛾生物学特性及防治试验

在福建省仙游县开展桉树林油桐尺蛾的生物学特性观察与防治试验,结果表明:在福建仙游油桐尺蛾1 a发生3代,以蛹在土里越冬;翌年4月上旬—中旬成虫开始羽化,4月下旬为羽化盛期;第1代幼虫5月上旬孵出,5月下旬开始结茧化蛹,6月上旬成虫羽化,6月中旬为羽化盛期;第2代、第3代幼虫分别在7月上旬、9月中旬孵化,第3代幼虫10月下旬结茧化蛹进入越冬状态。采用溴氰菊酯烟雾剂进行应急化学防治可迅速降低虫口,灭幼脲Ⅲ号1 000倍液喷雾防治可控制该虫的危害。     

双叉犀金龟在豫南地区的发生规律调查研究

2006~2015年,在河南省舞钢市开展了昆虫双叉犀金龟(Allomyrina dichotoma)的发生与危害调查研究,通过野外危害观察与室内养殖观察,结果发现:其1年发生1代,5月下旬化蛹,6月上旬羽化,6月下旬产卵,7~8月下旬幼虫出现,开始活动,9月下旬幼虫在腐朽木头、锯末或杂草下进入越冬;幼虫主要危害栎、榆、板栗、杨及其它杂草根部幼根;成虫危害桃、李、杏等树种的嫩枝和果实。     

柽柳条叶甲生物学特性研究

柽柳条叶甲1a发生2代,以成虫在靠近树干基部的枯枝落叶下或土壤缝隙中越冬,翌年4月下旬开始活动,5月上旬开始取食危害并交尾产卵,5月中旬幼虫开始取食危害,老熟幼虫入土化蛹。第1代成虫于6月上旬开始出现,7月下旬出现第2代成虫。成虫、幼虫均取食危害。     

夹竹桃天蛾的生物学特性初步研究

夹竹桃天蛾在汕头一年发生3代,以蛹越冬。越冬代成虫于2月下旬开始羽化,第1代幼虫于3月上旬开始孵化,以5-6月、8-9月为幼虫取食高峰期。本文报道其生物学特性,并提出防治建议。     

危害白桦的新害虫——冷杉虎天牛

冷杉虎天牛在河北承德1a发生1代,以老熟幼虫在被害树木质部内越冬。翌年4月中旬越冬幼虫开始化蛹,5月中旬至6月上旬成虫羽化,成虫活动期到6月下旬,幼虫在皮下串食韧皮组织及边材,对新移栽的白桦危害严重。     

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.     

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。     

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.