麻黄丰产栽培技术

麻黄，也称草麻黄，为麻黄科草本状小灌木，全草可入药，草内含麻黄碱、伪麻黄碱，有发汗、平喘、止咳、利尿功能，根具止汗功能，因而人工栽培麻黄有着极高的经济、生态和社会效益。实际生产中一般采用育苗后移栽的方法栽培。 一、育苗 育苗地的选择：选择地势平坦、保水能力较强的沙壤土，水源条件好，排水通畅，地下水位不能过高，同时有足够的劳动力和便利的交通条件。 整地及施肥：秋季深翻、春季整平、精耕细作。结合整地每亩施３～５吨充分腐熟的农家肥，并对土壤进行消毒处理。 作床：按宽１．５米、长２０米作床，以高床效果最好。…     

白皮松容器苗育苗技术

<正>一、苗床地选择与整理苗床地应选交通方便、靠近居民点、有灌水条件、排水良好,土壤肥沃的平坦阳向沙质壤土地段。苗床整理:于先一年秋季深耕育苗地30-50厘米,耕后磨平。次年春季可开始做床。育苗可选低床,规格为:宽1.2米,长20米左右,深度以容器袋装土排放后刚好与地面平齐为宜,一般为12厘米左右,步     

柠条播种育苗技术

柠条具有萌发力强，耐土壤瘠薄等特点，是我区水土保持、防风固沙的先锋树种。近几年我们在柠条的育苗技术方面进行了探索，现介绍如下，供参考。一、整地作床育苗地最好秋季深翻，翌春作床——低床或高低合并床（１０米×３米），床做好后再用锹浅翻一次，并施足底肥，同...     

一年半生白柠条苗育苗技术

白柠条是“三北”地区防风固沙、水土保持的优良灌木树种。它不仅抗逆性强,而且有较好的利用价值。赤峰市北部地区培育的一年半生白柠条苗,适应性强、成活率高,优于一年或二年生的苗木造林,白柠条从直播造林到植苗造林,由使用一年生苗木(春季育苗,5月上旬播种)到使用一年半生苗木(夏季育苗,8月上中旬播种),不仅苗齐苗壮,且造林成活率明显提高,效果显著。1.苗圃地的选择、整地、作床苗圃地的选择:白柠条育苗应选择地势平坦、有灌溉条件、通透性好的土壤。整地:春季或初夏整地,深翻20cm左右或播前整地,并进行耙压。作床:有喷灌条件的,应该作床…     

狭叶红景天育苗技术初探

通过对采集到的野生狭叶红景天种子采用低温（0℃以下）、流水处理及对种子不作任何处理等不同方法进行比较试验,了解不同的处理方式对种子休眠期的影响,进而得出低温处理种子发芽率、出苗率及成苗率效果最佳。同时对春季育苗和秋季育苗进行试验比较,结果表明在甘南春季育苗比秋季育苗效果要好。     

秋季容器育苗

随着“五八”造林绿化规划的深入实施，容器育苗已得到迅速推广。但仅采取春季容器育苗还不能满足需要，安庆市于1991年秋季在一些灭荒任务重的山区县进行了秋季容器育苗试验工作，共完成黄山松和马尾橙容器育苗600万株。与春季相比，秋季容器育苗难度要大些，一是种子催芽和移芽正赶上秋季的高温和干旱；二是苗木需要越冬，叉遇上冬季的低温和严寒，总结经验教训，过好“高温、干旱、低温、严寒”四关，是秋季容器育苗的成功关键。     

高床育苗效果探讨

苗木生产中 ,育苗用的苗床分为高床、低床和平床 3种。山东属于降水较少且年内分布极不均匀的省份 ,使灌溉和排涝成为培育良种壮苗的重要措施之一 ,因此 ,大部分苗木生产单位都采用低床育苗 ,而忽略了高床育苗的优势。为探讨这个问题 ,我们连续多年进行了高床育苗实践 ,并与低床育苗效果进行对比分析 ,认为 :高床育苗有利于改善土壤肥力状况 ,苗木出苗早、出苗齐、出苗率高 ,苗木生长快 ,且节省投入。现将高床育苗和低床育苗效果分析报告如下 :1　基本情况高床育苗从 2 0 0 0年春季开始 ,在沂水县马站镇沙家庄村、乔家官庄村、杨家城子村苗…     

翅荚木轻基质秋季育苗技术研究

以顺昌县次生种源翅荚木种子为繁育材料,探讨不同基质配比、热水浸种催芽、移栽时期、施肥浓度对翅荚木秋季轻基质容器育苗的影响,并对比分析春季大田与秋季基质容器育苗的苗木生长及造林效果.结果表明,翅荚木秋季容器育苗比春季大田育苗缩短育苗期,减少育苗和造林成本,提高造林成效.以泥炭：椰康：珍珠岩配比为4：2：1的基质、80℃热水浸种催芽、种子露白点播及采用1％浓度复合肥追肥,育苗效果最好,当年平均苗高31.23cm,平均地径0.25cm,苗木出圃率90.0％,次年即可上山造林,成活率达98.0％.     

塑料大棚秋播秋移云杉苗

木茹苗圃位于道孚县木茹林区,春季解冻迟,霜期长。晚秋降温早,土壤结冻快,露天育苗只能春播,1年生苗木质化程度低,越冬死亡率高。因此我们在总结塑料大棚春播育苗经验的基础上,1980年8月进行了大棚秋季播种育苗,次年秋季移床培育试验。解决了在高海拔地带秋季育苗的降温和病害问题。缩短了苗木培育时间,提高了产苗量,降低了育苗成本,大棚每亩1年生苗可移植10亩,每亩成本仅为357元,露天培育2年生苗,1亩只移2.5亩,每亩成本达1336元,约为大棚的4倍。大棚内一年生鳞皮云杉,平均苗高4.28厘米,基径0.085厘米,叶片67片,主根长约9厘米,千株苗地上部分     

沙荒地文冠果播种育苗技术试验研究

针对沙荒地文冠果种子育苗存在的出苗率低、出苗不整齐、苗木质量差等问题,选择播种时期、覆盖方式、种子处理方法、播种方式4个影响因素作不同处理组合对比试验分析,结果表明：春季文冠果种子育苗以4月25日播种,采用覆膜＋沙覆盖方式,种子高温催芽,覆膜点播的组合方式最佳,其出苗率和生长量明显高于春播的其他处理组合,是沙荒地文冠果春季播种比较理想的组合方式;秋季育苗其出苗率比春播处理组合平均高22.8%,苗木地径比春播平均高31.6%,即10月28日播种,采用土覆盖,种子不处理,开沟条播的处理组合是秋季文冠果沙荒地育苗的最佳选择。     

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.     

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。     

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.     

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.