黑龙江省杨树栽培生态气候区区划模糊聚类分析

筛选出8个与杨树生长相关性较强的气候因子作为聚类分析的指标,采用模糊聚类分析方法,对黑龙江省杨树栽培气候区进行了区划,区划结果为黑龙江省杨树栽培区划为三江平原湿润、半湿润区,松嫩平原东部半湿润、半干旱区和松嫩平原西部半干旱区,确定了各区划区的主栽杨树品种。为各地区制定丰产林规划、丰产林标准及栽培技术措施提供可参考的依据。     

3个杂交杨无性系生长节律的研究

盖杨、辽宁杨和辽河杨为辽宁杨树所培育的杂交杨无性系经栽培试验，其生长节律和物候期均与沙兰杨相似，因此，在适于栽培沙兰杨地区都可栽植这３个无性系。辽宁省以辽南平原较湿润区和辽西平原丘陵半湿润区为最适宜生长区。     

3个杂交杨无性系生长节律的研究

盖杨、辽宁杨和辽河杨为辽宁杨树所培育的杂交杨无性系经栽培试验，其生长节律和物候期均与沙兰杨相似，因此，在适于栽培沙兰杨地区都可栽植这３个无性系。辽宁省以辽南平原较湿润区和辽西平原丘陵半湿润区为最适宜生长区。     

速生杨树良种在辽宁省的区域栽培

对当前辽宁省栽培推广的主要速生杨树品种，按着影响其生长的气温、降水、土壤等主导因子，根据不同品种的生物生态特性，进行了大体的自然栽培区划。在栽培区划中将我省区分为西部丘陵干旱区、西北部沙旱瘠薄区、辽北低丘平原半湿润区、辽河平原半岛半湿润区及东南部湿润区、东部山地低温区、辽河下游低地盐土区等6个不同栽培生态区。把当前生产中主要栽培的杨树品种，划分为喜温型、较喜温型、中温型、较抗寒型、耐碱型等类型。并在上述各生态区内进行了布局，为以后栽培推广提供了适地适树、适地适品种的依据。     

应用星座图聚类法划分杨树栽培区的研究

本研究以晋中地区的地理、气候等生态因子的调查资料及主栽杨树品种的生长调查材料为依据，应用星座图聚类法将该地区划分为５个栽培区：Ⅰ．平川温暖干旱区；Ⅱ．平川东部丘陵温和干旱区；Ⅲ．东山丘陵温和半干旱区；Ⅳ．低山温凉半湿润区；Ⅴ．中山温寒湿润区。同时，用生产上常用种北京杨，对各栽培区生产力差异等进行显著性检验与分析，说明Ⅲ区是杨树生长的最适宜地区，Ⅳ、Ⅰ区次之，Ⅱ、Ⅴ区居后。应用星座图聚类法作杨树栽培区划，使分区建立在数学的基础上，模型化，直观化，进而科学地解决了杨树丰产品种的布局及良种栽培的优化选择问题     

应用星座图聚类法划分杨树栽培区的研究

本研究以晋中地区的地理，气候等生态因子的调查材料为依据，应用星座图聚类当将该地区划分为５个栽培区：Ⅰ．平川温暖干旱区；Ⅱ，平川东部丘陵温和干旱区；Ⅳ，低山温凉半湿润Ⅴ．中山温寒湿润区。     

我国湿地松人工林种植范围的立地气候分区研究

利用我国湿地松分布区内２２２个气象站点的１０ａ气候资料的平均值，用主成分分析法，将湿地松栽培区划分为４个立地气候区，即：Ⅰ．南亚热带、热带沿海立地气候区；Ⅱ．中亚热带丘陵立地气候区；Ⅲ．暖温带、北亚热带丘陵、平原、岗地立地气候区；Ⅳ．湘、鄂、川接壤山地，四川盆地，黔东南立地气候区．再在各气候区内实测有代表性的８～１０ａ的湿地松标准地１７１块，分别采用平均胸径、平均树高、平均单株材积证实各气候区内湿地松生长差异．这４个立地气候区可作为湿地松人工林立地类型划分、立地质量评价等经营数表编表单元的依据．     

濉溪县果树栽培现状及发展对策

濉溪县位于安徽省北部、黄淮海平原中部，与黄河故道南缘接壤，果树资源较丰富。全县低山残丘占总面积的3％，其余为平原，属暖温带半湿润气候区，年均气温14．5℃，极端最高气温41．1℃，极端最低气温-21．3℃，年平均降水量839．2mm，日照时数2293．7h，蒸发量1768mm，无霜期203d，对果树生产极为有利。七十年代以来，果树栽培面积大幅度增长。     

慈竹生态环境及培育技术初步研究：（Ⅱ）培育技术

本文采用数量分类方法,进行了四川盆地慈竹栽培区划和盆东南丘陵区立地类型组划分;同时,提出了慈竹经营管理的有关措施.结果表明:(1)四川盆地可划分为4个栽培区,即盆东南丘陵区、盆北深丘区、盒地西缘区、川西平原区.其中盆地西缘区为最适宜发展区,盆东南丘陵区和川西平原区为适宜发展区,盆北深丘区为限制发展区.(2)盆东南丘陵区按地形特征可划分为8个立地类型组.(3)慈竹经营管理的主要技术措施是灌溉、打蔸垫土、松土、合理采伐等.此外,文中对慈竹的适生气候条件及丰产结构进行了讨论.     

对杨树品种在辽宁各地发展的建议

通过对全省杨树重点栽培区和主栽区的调查，指出了辽宁省杨树品种发展过程存在的问题，由于苗木市场的炒作，致使全省杨树品种混乱、良莠不分，给林业生产部门造成巨大经济损失。针对目前的现状，根据辽宁自然概况，将全省划分成9个杨树栽培生态区，提出了各生态区的适栽品种，旨在为生产部门提供参考，同时也对杨树品种发展方面提出几点建议。     

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.