林木种子de质检操作流程

种苗质量是林业工程建设成败的关键。林木种子质量检验是林业工程质量管理的第一道关口。在此介绍一套节时高效的林木种子质量检验操作流程。林木种子质量检验是用随机抽取的样品质量代表种批整体质量的分析方法。根据林木种子质量检验规程 (GB722-1999)主要检验项目有净度分析、发芽测定、生活力测定、优良度测定、种子健康状况测定、含水量测定、重量测定,依据林木种子质量分级标准 (GB7908-1999)应检测净度、发芽率、生活力、优良度、含水量的五项或部分指标。送检样品实验室分析过程中该五项指标检测流程,主要是净度测定结束后其余四项测定交替进行的统筹安排。     

林木种子检验

种子品质的概念,包括播种品质和遗传品质,遗传品质是基本的,但良好的遗传品质必须通过良好的播种品质才能实现。林木种子检验就是对林木种子的净度、千粒重、含水量、发芽能力、生活力、优良度、病虫害感染程度进行鉴定,以评定种子的播种品质。     

紫穗槐种子检验指标的通径分析与回归分析

按照国家标准局发布的《林木种子检验方法》(GB2772—81),将林木种子检验指标确定为8项,即净度、千粒重、发芽势、发芽率、生活力、优良度、含水量和种子病虫害感染程度。在8项指标中尤以发芽率这一指标显得特别重要,它能够为种子投入使用提供可靠的信息。本文以紫穗槐种子为例,研究分析种子检验指标之间的通径相关关系,并建立一元线性回归方程式对种子发芽率进行预测,目的在于能否不搞发芽试验,而通过其它检验指标对发芽率进行预测。     

怀槐种子性状的测定

从桓仁县八里甸子镇国营林场采种基地的林分内采集怀槐种子,按国家标准进行种子有关性状的测定。结果表明,桓仁产地的怀槐种子的净度为95.0%、发芽率为86.3%、优良度为97%、千粒重为55.6g;与哈尔滨市栽培怀槐的种子相比,发芽率相近,千粒重和净度均高于哈尔滨市的次生种源。     

林木种子质量5项指标测定简易流程

<正>种苗质量检验是林业工程质量管理的第一道关口。为节时高效完成林木种子检验任务,提高检验效率,现根据工作经验介绍一套测定林木种子净度、发芽力、生活力、优良度、含水量等5项指标的简便高效操作流程。     

林业职工技能开发讲座(八)

六、林木种子品质检验7、怎样测定林木种子重量？（1）林木种子重量测定的意义及表示方法：种子重量是种子质量的重要指标之一，可用干粒重或容重表示，通常使用千粒重。即1000粒气干纯净种子的重量，以克表示。千粒重可反映种子的大小及饱满程度，是计算田；司播种量的依据。（2）林木种子干粒重的测定方法①百粒法多数种子应用百粒法。从净度测定所得的纯净种子中，随机取100粒的一组．共取八组，即为八重复。分别称量各重复的重量，记入相应表格。称量精度同净度测定精度。计算八组的平均重量、标准差及变异系数，其公式为；式中X──各…     

辽宁岫岩地区日本落叶松优良家系种子品质筛选研究

以辽宁岫岩地区日本落叶松(Larix kaempferi)种子园的优良家系的种子为研究对象,测定种子净度、千粒质量、优良度及活力指标,以筛选日本落叶松优良家系。结果表明:种子净度间差异不显著,以358号最高;种子千粒质量间差异显著,以358号最高;种子优良度间差异显著,以167号最高;种子生活力间差异显著,以167号最好;种子品质分析中,18、182、120、74、89、358、188、233、12的种子品质属于优良水平。     

湖南省主要经济林树种(品种)种子等级标准的研究

由申南林学院和湖南省林业厅共同研究完成的《湖南省主要经济林树种（品种）种子等级标准的研究》1993年12月通过由省林业厅组织的鉴是。专家认为，该项研究居国内同类研究领先水平。该成果对我省范围内的11个主要经济林树种种子的收购、贮藏和播种实践有一定的指导意义。研究人间建议种子分级指标为：①杜仲：一级种子发芽率为80％，净度为98％；二级种子发芽率为65％，净度98％；三级种子发芽率50％，净度96％。含水量为30％－55％。②葡萄桐：一级种子发芽车95％，净度98％．二级林子发芽率85％，净度98％，三级种子发芽率65％，净度96％…     

防风种子品质检验及质量标准研究

对全国不同地区防风种子的品质进行测定,研究防风种子的检验方法和分级标准,测定了不同产地的防风种子的净度、千粒重、含水量、生活力、发芽率,并初步制定了防风种子的质量分级标准。     

微机APPLEⅡ在林木种子检验试验室中的应用

在国家标准“林木种子检验方法”总则中写到,“为保证和提高种子质量,减免种子的损失与浪费,凡是经营和使用种子的单位,在采收、贮存、调运和播种时,均须进行种子质量检验。检验的内容包括抽样、种子净度测定、种子千粒重测定、种子发芽测定、种子生活力测定、种子优良度测定、种子含水量测定、种子病虫害感染程度测定,以及复验和仲裁检验。”林木种子检验试验室就是为此而建立的。 为提高林木种子检验试验室的科学管理水平,减少计算差错,提高精度,加快测定和检验的速度,提高工作效率,使试验室工作向现代化迈进一步,我们将Apple Ⅱ(苹果Ⅱ)微     

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.     

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.     

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.