几种中长期化学采脂刺激剂的性状及其应用

介绍近年来在化学采脂方面推广应用的几种中长期采脂刺激剂增产灵-2号，9205低温采脂剂、松树增脂剂、松树增脂剂的性状及使用方法。     

油松松脂采脂技术简介

在油松松脂采割试验的基础上，总结出了采脂林分及采脂树个体选择、割面方向选择、采脂起始高度、刮面配置、采脂工艺、采脂间隔期、采脂期确定等技术要点，符合油松采脂林木特性，适宜油松采脂作业，技术可行。     

采脂结合施用松树增脂剂对湿地松中龄林生长的影响及效果分析

对湿地松中龄林进行采脂，研究采脂对其生长的负效益，并结合增脂剂的应用，测试其增产效果和对林木生长的促进程度，为湿地松中龄林大面积进行采脂开发和增脂剂的推广打下理论基础。     

湿地松采脂试验报告

本试验以大田县桃源林场13年生的湿地松为材料,对湿地松产脂量、最佳采脂间隔期的选择、采脂对湿地松生长量的影响进行试验研究,并采用方差分析等方法,对湿地松7种不同处理方法进行差异显著检验,确定合理的采脂间隔期。结果表明,胸径17cm的湿地松平均单刀产脂量为32g;采脂间隔期3—5天,不仅产脂量较大,而且对湿地松生长量影响小。     

河南省马尾松采脂量与树体因子关系的研究

通过设置１４块标准地进行采脂试验研究，结果表明，马尾松采脂量与采脂树木的胸径、树贞与树冠大小呈一元线性回归关系，其中采脂量与胸径相关关系极显著，在胸径为１６ｃｍ时，年采脂量为２．５６４ｋｇ；根据我省马尾松资源现状，、应贯彻以生产木材产品、生产松脂为副产品的经营原则；采脂树木胸径应不于１６ｃｍ，以下降式采脂方法为宜。     

松树钻孔法采脂技术研究

以我国最主要的采脂树种马尾松、湿地松进行钻孔法采脂试验,探索了不同钻孔工艺和受脂方法对产脂量的影响以及钻孔法采脂对松树生长的影响.试验结果表明,马尾松钻孔用溶脂剂处理对延长其流脂时间和提高产脂量无明显效果;湿地松采用钻孔法采脂,产脂量除受树径大小影响外,还与孔径大小、钻孔方法、受脂方法等钻孔工艺条件有关,其影响程度孔径大小＞钻孔方法＞受脂方法;就单株采脂树的年产脂量而言,湿地松钻孔法采脂比常法采脂低,但钻孔法采脂可间隔20～30 d钻一次孔,对提高采脂劳动生产率有一定作用;钻孔法采脂对松树生长的影响比常法采脂小得多,有利于松树在采脂期间的生长.     

红松采脂试验初报

通过对29～30年生红松采脂试验得出，单株采脂量与径级、季节相关紧密：与采脂负荷率关系不大，但与林分株密度相关显著，为人工红松采脂提供一定经验。     

湿地松采脂研究

通过对近几年来在湘潭、株洲、衡阳等地的调查研究，分析了湿地松的产脂状况和特点，总结出其产脂曲线、单刀产脂量和年产脂量等规律，肯定了湿地松采脂的显著经济效益和社会效益。     

马尾松小径材化学采脂效益分析

利用化学采脂方法，对马尾松小径材进行伐前采脂试验，结果表明，利用化学采脂能大大提高劳动生产效率，降低小径材伐前采脂成本。同时小径材的平均单株采脂量也得以提高，较大幅度地提高了马尾松小径材的利用价值和经济价值。     

不同强度采脂对马尾松生长的影响

通过采脂试验,研究不同采脂强度对马尾松中龄林生长的影响,结果表明:采脂对马尾松中龄林的生长有影响,随着采脂强度的提高,对其生长的影响越大.不同采脂强度对胸径年生长量与材积年生长量的影响较大,对树高年生长量影响则不明显.随着采脂强度提高,产脂量也随之提高,但采脂降低了木材质量,木材利用率低,不利于培养大径材.建议在马尾松中龄林中禁止60%以上超负荷采脂.     

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.     

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。     

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.