本种加勒比松自由授粉家系的遗传变异分析与早期选择

根据本种加勒比松(Pinus caribaea var.caribaea)23个自由授粉家系的8 a生子代测定数据,研究其生长性状的遗传变异,结果显示:树高、胸径、单株材积的单株狭义遗传力为0.24、0.14.、0.19,树高、胸径、单株材积、蓄积量的家系平均遗传力为0.68、0.59、0.67、0.75;参试家系间存在极显著生长差异(P＜0.01),根据蓄积量选择出5个优良家系,分别是19-Ⅳ、石8、石9、石10、石11,其年均树高1.27 m,年均胸径2.17 cm,每公顷年均蓄积量14.79 m3,蓄积量的现实选择增益为30.49％、预期遗传增益为22.87％.     

柚木种子园自由授粉子代家系测定及早期选择

柚木(Tectona grandis)种子园自由授粉子代家系大田测定的初步结果显示:不同家系1～3 a生树高存在显著(P＜0.05)或极显著差异(P＜0.01),家系保存率为50％～100％,树高和胸径变异系数分别为0.21和0.27,遗传力分别是0.50和0.27,由3a生树高筛选出优良家系26号、35号和4号,树高和胸径遗传增益分别为6.43％和3.40％.     

长白落叶松半同胞子代测定及优良家系的选择

对长白落叶松初级种子园优树子代测定林(24a生)17个家系的树高、胸径和立木材积进行分析的结果表明:树高、胸径、材积均差异极显著,且生长性状之间呈显著正相关关系。以材积性状作为主要指标,同时兼顾树高、胸径指标,对参试家系进行选择,选出4个优良家系。     

柳杉一代种子园半同胞家系遗传变异分析

以福建省霞浦杨梅岭国有林场柳杉一代种子园5年生家系为研究对象,对子代林树高、胸径、材积和冠幅等生长性状遗传变异进行了测定与分析。结果表明:家系胸径、树高、材积、冠幅平均值分别为11.64 cm,6. 75 m,0. 040 3 m3,2. 07 m,27个参试家系材积生长量均大于对照;生长性状总体变异系数为材积胸径冠幅树高,家系内变异系数大于家系间变异系数;方差分析表明,家系间胸径、树高、材积存在极显著差异,冠幅差异不显著;柳杉半同胞子代林胸径、树高、材积、冠幅的家系遗传力分别为为0. 41,0. 16,0. 36,0. 16,单株遗传力分别为0. 78,0. 60,0. 76,0. 33;各性状期望遗传增益分别为6. 75%,0. 47%,11. 79%,0. 52%,现实增益分别为16. 47%,2. 92%,32. 76%,3. 27%,27个家系生长表现优异。研究结果可为探索子代林生长变异规律,一代种子园管理、杂交育种、优良家系(无性系)评选,及下一代育种群体构建提供参考。     

樟树无性系组培苗丘陵山地造林早期生长分析

以樟树(Cinnamomum camphora)无性系组培苗营建试验林,对林木1~5a生生长情况进行调查分析。结果表明：1a生幼林的平均树高和冠幅的分别为1.12m和1.1m;3a生平均树高、平均冠幅和平均胸径分别为3.34m、1.4m和2.94cm;5a生平均树高、平均冠幅和平均胸径依次为5.35m、1.68m和4.8cm,分别比3a生时增加60.01%、20.1%和63.26%。不同林龄的树高有极显著差异（P＜0.01）;5a生和3a生的胸径有显著差异（P＜0.05）,但冠幅差异不显著。树高、冠幅和胸径在区间组间差异均不显著,表明群体的生长表现较一致。     

杉木第二代种子园单亲子代测定及联合选择

利用80个杉木第二代种子园单亲子代家系在福建省卫闽国有林场营建子代测定林,对连续5 a调查数据的分析结果表明,不同家系各年树高、胸径、材积、冠幅差异均达极显著水平。遗传参数估值表明,除冠幅外的其它生长性状均受到中度的遗传控制。利用试验林3年生和5年生时的树高、胸径、材积构建指数选择方程组对参试子代进行联合选择,评选出甲2、戊1、丁96等8个优良家系及这些家系内的I1、I2、I3等15个优良个体;评选出的优良家系5年生时树高、胸径、材积平均遗传增益分别为2.61%、6.39%和16.98%,优良个体5年生时平均树高、胸径、材积比群体均值分别大29.41%、76.39%和231.77%;研究结果还表明丁65、乙22、丁32等7个家系生长表现极差,应予以淘汰。     

长白落叶松初级种子园优树子代测定及优良家系的选择

对长白落叶松初级种子园优树子代测定林(19年生)37个家系的树高、胸径和立木材积进行分析的结果表明:树高、胸径、材积均差异极显著,且生长性状之间呈显著正相关关系。以材积性状作为主要指标,同时兼顾树高、胸径指标,对参试家系进行选择,选出10个优良家系。     

樟树局部种源早期选择研究

对广东省局部樟树种源开展了苗期试验和造林测定,根据苗期苗高、地径和种源/家系测定林树高、胸径等性状的生长量,分析比较局部种源的生长差异,结果表明樟树种源间1 a生苗高、地径生长量差异极显著,5 a和7 a生的种源间胸径和单株材积生长量在广东省东江林场试验点差异显著。采用多目标决策分析法,分地点对参试种源进行评定和选择,评选出在2个试验点早期生长较快且表现稳定的优良种源2个,分别是粤东和粤西沿海种源。入选种源造林后7 a生的树高、胸径和单株材积生长量的选择增益分别为1.04％～1.63％、3.12％～3.23％和5.75％～6.44％。     

无土栽培蝴蝶兰的方法及注意事项

对长白落叶松初级无性系种子园优树子代测定林（23a生）17个家系的树高、胸径和立木材积进行分析的结果表明：树高、胸径、材积均差异极显著。以材积性状作为主要指标，同时兼顾树高、胸径指标，对参试家系进行选择，选出9个优良家系，其中2个为最优家系。     

长白落叶松初级无性系种子园优树子代测定研究

对长白落叶松初级无性系种子园优树子代测定林（23a生）17个家系的树高、胸径和立木材积进行分析的结果表明：树高、胸径、材积均差异极显著。以材积性状作为主要指标，同时兼顾树高、胸径指标，对参试家系进行选择，选出9个优良家系，其中2个为最优家系。     

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.     

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。