板栗扦插繁殖的系统研究

本文系统研究了板扦插繁殖技术，插穗生根特性，嫩枝扦插不定根形成的细胞组织学基础和嫩枝扦插生根过程中营养物质的消长规律。结果表明，板栗嫩枝扦插，经ＨＬ－４３生根剂（自制）处理，在全光照喷雾条件下，生根率可达８０％以上；插条生根率与母树年龄、枝条木质化程度呈负相关；扦插时间以５月中旬～７下下旬最适宜，８月后生根率下降；插条部位以中部条生根率最高，基部条次之，梢部条最差；不定根主要发生于韧皮部和维管形成     

新疆杨全光喷雾扦插育苗试验研究

新疆杨扦插育苗、全光喷雾，插穗选母树根部当年萌生条，基质用消毒珍珠岩，生根剂浓度５００ｐｐｍ，生根率分别为９０．２％和９２．１％。６－７月中旬可完成两次循环。     

板栗嫩枝扦插繁殖技术研究

１９９２～１９９５年共扦插１．６万株板栗插条,成苗率由１９９２年的２６％上升到１９９５年的９６．６％。试验从插条的选择、环境的控制、生根剂的选配和不同扦插时期进行了较全面的探索,现将试验结果分述如下。１材料与方法１．１试验地概况试验地设在江苏省溧阳市...     

重瓣黄刺玫嫩枝扦插育苗技术

重瓣黄刺玫嫩枝扦插育苗试验结果表明：在７月中旬剪取１－２年生幼龄树当年生半木质化枝条中段作插穗，在全光间歇喷雾条件下，以至石为基质扦插生根率可达９８％。用植物生长剂，磁化水对嫩枝扦插生根率无显著影响而对生根量有显著影响。     

重瓣黄刺玫嫩枝扦插育苗技术

重瓣黄刺玫嫩枝扦插育苗试验结果表明：在７月中旬剪取１－２年生物幼龄树当年生半木质化枝条中段作插 穗，在全光间歇喷雾条件下，以蛭石为基质，扦插生根率可达９８％，用植物生长调节剂，磁化水对嫩枝插穗生根率无显著影响而对生根量却有显著影响     

竹柏嫩枝扦插育苗试验初报

从竹柏树冠中、上部选取当年或１年生的嫩枝作插穗、，按不同时间、不同浓度的生长激素处理和不同的基质等３方面进行试验，结果表明：竹柏可以进行嫩枝扦插，且成活率高，最高可达９８％以上；扦插时间以３月上、中旬最佳，其次是９月中旬；激素处理有利于竹柏扦插生根，但浓度不宜过大，浸泡时间不宜过长，以ＡＢＴ－１号生根粉０．５h为宜；在基质选择上，应选择肥力条件、透气保水力等都较好的土壤。     

水曲柳硬枝扦插技术

水曲柳硬枝扦插技术据黑龙江林科所朴楚炳等研究试验，水曲柳采用硬枝扦插，配合生根剂处理，扦插生根率可达８５％－８６．７％。扦插方法：（１）插穗采自１年生实生超级苗，扦插时间５月１－５日。从剪取插穗到扦插不超过３６小时，扦插深度５ｃｍ。（２）池状低床，床...     

栓皮栎扦插繁育技术研究

通过不同生根剂浓度、基质、母树不同位置穗条以及扦插时间等因素对栓皮栎扦插生根影响的试验研究。结果表明：不同生根剂、不同基质、穗条位置以及不同扦插时间对插穗生根影响达显著水平,栓皮栎穗条扦插存在位置效应,以母树中上部穗条扦插生根效果最佳;不同季节扦插生根率也存在明显差别,以3月扦插效果最好;用生根剂（ABT1）处理穗条,均促进扦插生根,生根剂ABT1号处理以600mg·L^-1浓度处理生根效果最好,生根率达92．8％;以红心土＋河沙＋火烧土为基质（比例为1：1：1）,插穗生根率最高。栓皮栎扦插最佳的处理组合是采用中上部德条、以红心土＋河沙＋火烧土为基质（比例为1：1：1）、用ABT1号600mg·L^-1浓度处理穗条、选择3月份扦插。     

重瓣黄刺玫嫩枝扦插育苗技术

重瓣黄刺玫嫩枝扦插育苗试验结果表明：在７月中旬剪取１～２年生幼龄树当年生半木质化枝条中段作插穗，在全光间歇喷雾条件下，以蛭石为基质，扦插生根率可达９８％，用植物生长调节剂、磁化水对嫩枝扦穗生根率无显著影响而对生根量却有显著影响。     

西伯利亚落叶松嫩枝扦插育苗技术研究

西伯利亚落叶松扦插较难生根，１９９２～１９９３年在哈密林木良种基地进行了全光喷雾嫩枝扦插育苗试验。结果表明，以锯末为扦插基质，用１．５ａ生西伯利亚落叶松嫩枝扦插，平均生根率达到８０．３９％；平均生根数量５．８６条，每穗平均根长１．７８１ｃｍ。初步认为，提高西伯利亚落叶松幼龄母树嫩枝扦插生根效果的最佳组合是：锯末（基质），扦插密度２ｃｍ×４ｃｍ，生根粉（ＡＢＴ）５００μｇ／ｇ，插条长度８～１０ｃｍ。     

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.     

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.     

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.     

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.