云南中部辐射松引种试验

为丰富我省的树种资源,提高林业生产水平,我院从1964年始,曾先后从林业部引进的松树种中得到湿地松、火炬松、海岸松、意大利松等进行栽培试验。1982年。又从北京种苗局得到辐射松、湿地松、加勒比松三个国外松树种,作进一步引种试验。为使所得数据可靠,我们严格按照田间试验设计的要求,并用乡土树种云南松作时照进行栽培对比试验。4年来的生长情况证实,辐射松在参试的4个树种中名列前矛。     

马尾松引种试验初报

为丰富我省的造林树种,提高林业生产水平,1981年在开展云南松地理种源选择的同时,从外地引进了湿地松、火炬松、海岸松、乔松、高山松、马尾松,并用昆明地区的云南松作对照。在同等条件下,开展了田间栽培对比试验。7年来的生长情况表明,马尾松的生长量(指高、径)都超过对照和参试的其他树种,现将该树种的引种情况介绍如下。一、马尾松的分布概况马尾松(Pinus massoniana Lamb)是我国松树中分布数量最多的主要造林用材树种之一,北可分布到淮河,伏牛山,秦岭一线,南至广东、广西的南部,东自东南沿海和台湾,西达贵州中部及四川大相岭以东。     

火炬松,湿地松,短叶轮,晚松在宝应京杭大运河堤引种研究

在我国暖温带宝应运河堤碱性土壤上引种火炬松，湿地松，短叶松和晚松，９年生时全部进入速生期，１３年生平均树高１２．３１ｍ（火炬松）～１０．２２ｍ（晚松），胸径１８．７０ｃｍ（火炬松）～１２．６３ｃｍ（晚松），均超过了南方引种试验林标准。高、径年生长节律亦与亚热带地区相似。不同树种生长差异极显著，火炬松＞湿地松（美国佐治亚源）＞湿地松（广东台山种源）＞短叶松＞晚松。保存率都很高，但在不同树种间差异不显     

火炬松和湿地松出材率及营林成本调查

为了给黔中地区建立坑木和纤维和材基地树种选择作参考，对火炬松，湿地松、马尾松三树咎调查结果，湿地松和马尾松商品材出材率接近，但湿地松树皮率较高，营林成本：马尾松大于火炬湿地松，湿地松大于火炬松，营林周期不宜超过２５年。     

国外松采脂试验初报

１７年生松类林木的采脂试验表明，湿地松的松脂产量为马尾松的２．４７倍，大炬松为马尾松的１．２２倍。通过施用增脂剂，湿地松增加松脂产量３７．８％，火炬松增加４４．４％，马尾松增加２３．５％。     

火炬松、湿地松、短叶松、晚松在宝应京杭大运河堤引种研究

在我国暖温带宝应运河堤碱性土壤上引种火炬松、湿地松、短叶松和晚松，９年生时全部进入速生期，１３年生平均树高１２．３１ｍ（火炬松）～１０．２２ｍ（晚松）；胸径１８．７Ｃｃｍ（火炬松）～１２．６３ｅｍ（晚松），均超过了南方引种试验林标准。高、径年生长节律亦与亚热带地区相似。不同树种问生长差导极显著，火炬松＞湿地松（美国佑治亚种源）＞湿地松（广东台山种源）＞短叶松＞晚松，保存率都很高，但在不同树种间差异不显著，说明４种国外松都能适应宝应运河堤及相似地区生长。引种成功的关键技术是采用容器苗带土（松菌根真菌）造林。     

闽南沿海多树种引种及木麻黄与湿地松等树种混交试验

在闽南沿海沙地引进3种桉类树种、3种松类树种进行试验,并营造木麻黄与湿地松、马占相思、乌墨、柠檬桉混交林。经4年观测认为,柠檬桉、巨尾桉、刚果桉3种按树在沿海沙地适应性强、生长量大小分别为巨尾桉>刚果桉>柠檬桉;湿地松、火炬松、加勒比松3种松类树种只有湿地松在砂质海岸适应性强,火炬松和加勒比松长势弱;木麻黄与湿地松、柠檬桉混交效果比木麻黄纯林好。     

不同种源火炬松和湿地松木材基本密度和管胞长度的变异

对1984年种植在广西和浙江的22个种源的火炬松及在浙江的8个种源的湿地松的木材密度和管胞长度进行了测定和分析。结果表明,两个树种的木材密度和管胞长度在种源间和种源内单株间均表现出显著差异,但株间差异较种源间差异显著得多。不同地区火炬松的差异较之同一地区不同种源间的差异更为显著。种源、地区的交互作用对火炬松的木材密度和管胞长度都表现出显著影响,种源和单株的交互作用对两个树种的木材密度也有显著影响。两个树种的木材材性与年轮宽度之间没有显著的相关关系。与马尾松和早期引种的火炬松、湿地松比较表明,用新引进的材料可选育出木材材质更为优良的品种。     

火炬松优良种源/家系的选择

以湿地松和马尾松为对照,对5年生火炬松的种源/家系的生长情况进行了分析.结果表明:火炬松的生长量远高于马尾松,较高于湿地松;火炬松的种源/家系间存在显著差异,各生长性状的遗传力较高,遗传变异系数也多在10%以上,且种源的各参数较高于家系;综合评定值位于前3位的种源依次为SC、ZJ和FJ;对家系的遗传距离进行了聚类分析,确定了5个极速生家系、8个较速生家系,其材积增益与湿地松相比分别为44%和14%,与马尾松相比分别为197%和136%.     

国外松扦插育苗

国外松(湿地松、火炬松等),是生长快,材质好,干形圆满通直,适应性强的优良速生用材树种。我国引种三、四十年的历史证明,是南方丘陵山区的重要造林树种之一。目前种源奇缺,严重影响发展。为了尽快扩大种源,1975年南方十二省国外松良种科研协作会议确定以无性繁     

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.     

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.     

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。