松纵坑切梢小蠹防治指标,经济阈值及空间分布型的研究

通过定时定位观察云南松松纵坑切梢小蠹危害程度与云南松经济损失之间的关系，经统计分析，确定松纵坑切梢小蠹的防治指标为：平均虫孔数０．１８９虫孔／株。林木平均枯死率０．５２％。平均株枯梢率４．７４％，有虫株率５．１４％，确定昆明地区方旺林场的经济阈值为０．２１５１虫孔／株；并制订了适合于基层林区的多个动态经济阈值。     

云南松纵坑切梢小蠹成虫发生量预测预报研究

１９９２～１９９５年在玉溪市北城镇刺桐关办事处石狗头村，对云南松纵坑切梢小蠹进行了系统的调查及试验研究，得出小蠹成虫发生量的预测预报方法，即应用有效虫口基数法测报下一代小蠹成虫发生量，准确率达８５％以上。并初步建立了小蠹发生量的曲线回归测报模型：Ｙ＝０．１２９４０８８６４Ｘ０．９８７９１６５４２，相关因子为云南松受害株率，用于测报越冬代及下一代成虫发生量；多元回归测报模型：Ｙ＝－７９．０５２６＋０．４５０４Ｘ１＋５．３３６７Ｘ２＋０．１７１８Ｘ３±０．２５，相关因子是越冬虫口基数，４月上旬温度、雨量，用于测报下一代成虫发生量：二元回归测报模型：Ｙ＝－０．６２８２＋０．０４１５Ｘ１＋０．１１９２Ｘ２±１．５，相关因子是林木受害株率，用于测报越冬代及下一代小蠹成虫发生量。上述模型准确率均达８０％以上，具有较好的实用价值，为进行综合治理提供可靠的科学依据     

松纵坑切梢小蠹预测预报研究

纵坑切梢小蠹预测预报研究，采用聚集信息素诱集法、有效虫口基数法、云南松物候观测法进行发生期及发生量中短期测报，准确率达到８５％以上，在此基础上建立了发生期及发生量的计算机测报模型。确定蠹害林分内平均受害梢率４．７％，平均受害株率５．１％，平均枯死率０．５％为蠹害林分的防治指标临界值，在此指标下，可以不进行防治；根据发生量测报方法及防治指标在小蠹发生区进行多点测报即可确定小蠹发生区、发生范围及面积     

混交林抑制纵坑切梢小蠹危害作用研究

８０年代以来，云南全省云南松林区遭受纵坑切梢小蠹的猖獗危害，造成大量林木死亡。１９９２年在昆明市现有的云南松与栎类、云南松与华山松、云南松与滇油杉混交林及云南松纯林中，设置１１块定位观察样地，观察云南松混交林蠹害发生情况，１９９２～１９９５年经过４年的观察，混交林平均株受害率１０．９％，纯林平均株受害率４８．９％。混交林比纯林降低纵坑切梢小蠹危害率３８．０％。混交林内由于乔、灌、草种类的多样性，带来纵坑切梢小蠹天敌种类的多样性，有效地抑制纵坑切梢小蠹的发生与发展，形成有虫不成灾的生态环境     

落叶松枯梢病防治指标和为害指标的研究

本文通过对落叶松枯梢病不同病情与林木材积生长损失关系的研究结果， 建立不同新梢发病率与每公顷立木材积生长损失量的回归关系式为： ｙ＝ ２．９２７８／１＋ ｅ６．６１９６－ ０．１７４９ｘ。在此基础上， 根据当前生产防治效果和立木林价， 计算不同防治效果时的防治效益， 采用经济阈值法， 计算防治指标。制定出不同防治成本和防治效果时的防治指标查定表。以相对误差限法确定该病的为害指标为新梢发病率１５。     

落叶松枯梢病防治和指标为害指标的研究

本文通过对落叶松枯梢病不同病情与林木材积生长损失关系的研究结果，建立不同新梢发病率与每公顷立木材积生长损失量的回归关系式为：ｙ＝２．９２７８／１＋ｅ＾６．６１９６－０．１７４９ｘ。在此基础上，根据当前生产防治效果和立木林价，计算不同防治效果时的防治效益，有用经济阈值法，计算防治指标。制定出不同防治成本和防治效果时的防治标查定表。以相对误差限法确定该病的为害指标为新梢发病率１５％。     

混交林抑制纵坑切梢小蠹危害作用研究

８０年代以来，云南全省云南松林区遭受纵坑切梢小蠹的猖獗危害，造成大量林木死亡。１９９２年在昆明市现有的云南松与栎类，云南松与华山松，云南松与滇油杉混交林及云南松纯林中，设置１１块定位观察样地，观察云南松混交林蠹害发生情况，１９９２￣１９９５年经过４年的观察，混交林平均株受害率１０．９％，纯林平均株受害率４８．９％，混交林比纯林降低纵坑切梢小蠹危害率３８．０％，混交林内由于乔，灌，草种类的多样性，带     

落叶松枯梢病调查及综合防治

落叶松枯梢病是我国北方落叶松人工林的主要病害,被害林木轻则造成枯梢,重者树冠变形甚至整株枯死。从落叶松枯梢病的发病规律和发病诱因等方面做了阐述,并提供了基本的防治方法。     

利用幼虫粪粒数制定防治指标的研究

１９９２～１９９５年经过对枣步曲排粪规律、食叶量、枣树蓄叶量以及不同失叶水平对枣果产量影响的系统研究,建立了排粪量与平均气温的数量模型：Ｆ∧＝０．５６２９＋０．０１６２Ｔ,枣树蓄叶量估测模型：株蓄叶总面积＝株总枣股数×每股平均枣吊数×每吊平均枣叶数×平均枣叶面积,单位树冠面积下单位时间落粪粒数动态防治指标模型：Ｙ＝（２２６．１９４Ｘ３－３７３．７５４６）Ｘ－２３（０．５６５９＋０．０１６２Ｔ）,经林间验证,准确度在９０％以上。     

应用文山松毛虫质型多角体病毒大面积防治坝心林区文山松毛虫试？…

应用文山松毛虫质型多角体病毒（ＣＰＶ），于１９９１年、１９９２年、１９９４年，在献词主林区防治文山松毛虫，达１７２９．２７ｈｍ＾２，松毛虫开遍率分别为９０．７８％、８５．７％、８９．６％，示范林内固定样地的松毛虫校正死亡率达９３．２９％，有虫株率由９８．６％下降到２７．６６％，虫口密度由１４．２４头／株下降到０．６１８头／株。病毒能流行传染持续控制松毛虫的危害最佳防治虫龄是３～５龄，林间空气湿润的     

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.