木荷苗木性状的种源变异和地理模式

利用来自7省区36个木荷种源在浙江淳安和福建建瓯两试验点的苗期测定材料,研究其苗木生长、根系特征和叶片形态等12个性状的种源差异及其地理变异模式。方差分析结果显示,除主根长、侧根长和叶片颜色在种源间无显著差异外,其它性状的种源效应都达到显著或极显著水平。种源苗木性状与产地地理气候因子的相关分析发现,苗高、叶片特征(叶片数、叶片宽、叶片厚)及秋末嫩叶颜色等呈典型的纬向变异模式,产地温度则是造成这种纬向变异模式的主要环境作用因子。与北部种源比较,南部种源生长快,叶片数量多,但叶片较薄较窄,其秋末嫩叶颜色变化对寒冷信号反应敏感。影响木荷种子性状表型差异的主导因素是产地的年降水量。以苗高为标准,分别在两地点初选出优良种源10个,它们多来自25°N左右的木荷自然分布区。     

彩叶栾树新品种‘皇冠栾’

皇冠栾为天然变异植株,三季叶片金黄,经过7年田间品种对比试验,其叶色性状稳定,现已形成无性系.为优良的彩叶乔木树种.可以通过嫁接、播种等方法繁殖.适宜在我国全缘叶栾树分布区华东、中南地区种植.     

油松地理变异的初步研究

在由42个种源组成的全分布区种源试验中，测定了后代在发芽，物候，生长，形态和抗寒性等方面的21个特征，并据此阐明了油松地理变异的基本特点：（1）地理变异很显著，很普遍；（2）非连续性变异即生态型变异突出位置，也存在着随机变异；（3）各种变异特征与地理气候因素的相关关系比较复杂。     

细叶桉种源试验*

从澳大利亚引进的细叶桉１５个种源在海南省东部进行种源试验。５年生结果表明，种源间的树高、胸径、材积、保存率、干形和抗风性能等指标存在极显著差异，其中树高生长以来自昆士兰州的Ｋｅｎｎｅｄｙ河种源（１３４４３）和ＭＴ．Ｇａｒｎｅｔ种源（１３５４４）最好，分别为１２．６８ｍ和１２．６６ｍ。胸径生长以来自巴布亚新几内亚的种源（１３４１８）为最好（９．０５）。高纬度维多利亚州种源（１３３０３）生长最差，树高     

22年生试验林中黑核桃种源的表现

２２年生试验林中黑核桃种源的表现（美）Ｄ．Ｆ，Ｂｒｅｓｎａｎ等黑核桃（ＪｕｇｌａｎｓｎｉｇｒａＬ．）是美国中部硬材林中最有价值和最理想的树种。该树种的自然分布区从美国西部的东部地区延伸到南达科他州和德克萨斯州东部，整个分布区内的变异为速生原种的选择提...     

秃杉种源苗期变异与选择的研究

秃杉种源苗期试验研究表明，云南、贵州、湖北等８～１２个秃杉种源，７０个单株子代，种源群体间性状存在明显的遗传差异。性状变异与产地经向相关强於纬向相关的趋势。地理变异倾向於不连续遗传变异类型，以经向为主的渐变。经度偏东的贵州种源种子千粒重是湖北种源的１．６２倍，种源苗木生长快，生物量高，冠幅宽而长，根系发达。据对秃杉不同种源苗期生长发育，生物量测定１０个表型性状进行聚类分析，参照分布区生态特点，将秃杉分布区种源划分为３个种源区，２个亚区。变异、区划与选择为秃杉遗传改良提供了依据     

厚朴种源嫁接保存试验研究

在浙江磐安以湖南道县的中间型2年生厚朴实生苗为嫁接砧木,以收集的湖南、湖北、江西、广西、浙江、福建、贵州等种源地厚朴优树的枝条为接穗,用嫁接的方法开展了厚朴种质资源保存试验研究,结果表明:不同种源嫁接苗中,来自湖南桑植、广西融水、湖南安化等3个种源的嫁接成活率较高,嫁接后新稍生长较旺盛;湖南桑植种源嫁接苗苗高、地径生长量突出,广西融水、湖北利川种源嫁接苗叶片生长较好,江西庐山种源嫁接苗根系生长较好,贵州习水、江西庐山、广西融水种源嫁接苗生物量较大;中间型厚朴与中间型及凹叶型厚朴嫁接亲和性较高,且嫁接苗生长良好,适合用嫁接方法对其种源进行保存。     

窿缘桉种源试验初见成效

一、试验目的“种源”通常是指从同一个树种分布区中的不同地区收集种子(或无性系苗),同一树种长期在气候、土壤条件不同地区生长和发育,其形态、生理、生长、抗性以及适应性等方面会发生种种变异,有些变异是可遗传的,这种变异称种源变异。将一个物种的不同种源集中于一个地点进行育苗造林对比的研究就是种源试验。     

鹅掌楸种源遗传变异和选择评价

在中国鹅掌楸全分布区内抽样15个种源，于长江中下游5省区按统一试验设计营造种源试验林，7年生时全面测定其树高（H）、胸径（DBH）、冠幅（RC）等主要生长性状，进行遗传6变异分析，结果表明：中国鹅掌楸生长性状在种源间存在显著的遗传差异，地点间差异极显著，种源对环境反映灵敏，种源与地点间存在明显的交互作用，H、DBH和材积（V）的广义遗传力分别为0.503、0.526、0.521，受较强的遗传控制；RC受遗传控制程度相对较低（H^2=0.301)。相继进行了遗传稳定性、生长适应性分析和幼成龄相关分析，分析结果为种源选择和评价提供了理论依据，多点综合选择选出黎平、伤痛永两个优良种源，遗传增益11.8%。单点选择分别选出1-3个丰产种源，遗传增益达15.4%-51.5%。     

红锥中心分布区种源早期生长研究

文章对红锥中心分布区的广东、广西、福建主要种源进行早期生长比较试验。结果表明：中心分布区种源在广州龙洞地区生长差异明显，2年生时最优种源的排序是来自广西大青山、广东高州、广西客县、广东信宜、广东陆河。选择优良单株采种的效果明显优于普通混合采种，表型选优的材积平均生长增益达297．8％以上，各种源的早晚相关性均达到极显著水平，良种的区域性选择十分必要。     

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.