以森林乡村建设助力乡村振兴战略

该文主要从森林乡村建设的主要内容、建设机制、主要措施等方面介绍了森林乡村建设的发展方式。森林乡村建设的主要内容包括保护乡村自然生态,增加乡村生态绿量,提升乡村绿化质量,发展绿色生态产业等。主要建设机制包括政府主导、多种模式、会话先行、产业融合等;主要举措为打造精品、关注民生、培育产业、以奖代补、广泛宣传等。     

我国植物组培育苗发展概况

该文对我国组培育苗的主要目的、研究机构及生产单位、主要生产线、面临的主要问题及未来发展趋势等进行了简述。     

金丝枣主要病虫害及综合防治

主要介绍危害金丝枣的枣尺蠖、枣瘿蚊、星天牛、枣叶螨、桃小食心虫5种主要害虫和枣腐烂病、枣锈病两种主要病害的主要特点及发生规律,提出了其综合防治措施。     

贵阳市乌当区温泉经济发展SWOTS分析

本文对乌当区发展温泉经济面临的主要优势、劣势、机遇、威胁和措施进行了分析.主要优势包括温泉资源丰富、政府注重产业扶持、区位优势突出、市场开发前景广阔等;主要劣势包括产业基础薄弱、品牌效应不足、旅游市场单一等;主要机遇包括居民消费结构升级、温泉旅游升温等,主要挑战是同质化竞争和生态保护压力.文章同时提出了乌当区发展温泉经济的若干主要措施,从而有助于乌当区温泉经济可持续发展.     

贵阳市乌当区温泉经济发展SWOTS分析

本文对乌当区发展温泉经济面临的主要优势、劣势、机遇、威胁和措施进行了分析．主要优势包括温泉资源丰富、政府注重产业扶持、区位优势突出、市场开发前景广阔等;主要劣势包括产业基础薄弱、品牌效应不足、旅游市场单一等;主要机遇包括居民消费结构升级、温泉旅游升温等。主要挑战是同质化竞争和生态保护压力。文章同时提出了乌当区发展温泉经济的若干主要措施。从而有助于乌当区温泉经济可持续发展．     

佛山植物园各专类园植物规划

主要对佛山市植物园规划的背景、目标、选址、思路、主要功能分区进行了分析。佛山植物园的主要功能区包括了山茶园、珍奇植物区、抗污染植物区、药用植物区、南亚热带植物区、兰圃、温室植物区、生态修复区、科研行政管理区和游客服务区,将佛山植物园打造成为以山茶科为主要特色的精品植物园。     

实施森林可持续经营是林业发展的必然选择——关于吉林省森林经营工作的调查与思考

本文阐述了吉林省森林经营工作经历的主要阶段及主要做法和取得的主要成果,从认识、措施、资金、体制、制度、人员等6个层面分析了当前森林经营工作面临的主要问题,并针对存在的问题提出了推进森林可持续经营的对策与建议。     

郑州凤山森林公园植物季相景观研究

以郑州凤山森林公园为研究区域,通过实地调研和数据收集整理,分析植物季相景观组成和风貌特征,并结合卫星影像图标记植物季相空间分布。结果表明,该公园植物共计46科、87属、109种,其中以蔷薇科、豆科、槭树科为优势科。春季主要表现为花景,其中白蜡、迎春、碧桃分别主要表征白色、黄色和红色花景;夏季主要表现为花景和叶景,其中紫薇、七叶树、矢车菊分别表征红色、白色和紫色花景,银杏主要表征叶景;秋季主要表现为叶景和果景,其中银杏主要表征叶景,柿树和南天竹表征果景;冬季主要表现为果景、叶景和枝景,其中雪松主要表征叶景,火棘、冬青主要表征果景,红瑞木和金枝国槐分别表征红枝和黄枝景观。根据植物景观季相风貌特征,结合场地现状提出增加植物种类,加大花卉种植形式,处理好滨水空间与植物关系等相关优化建议。     

高尔夫球场景观设计研究

高尔夫球场景观由高尔夫硬质景观和高尔夫软质景观组成,其中高尔夫硬质景观可分为点、线、面三类。点的元素主要有建筑、沙坑、小品;线的元素主要有道路的起伏变化、驳岸的曲线等;面的元素主要是场地造型的变化。软质景观主要指植被和水体,植被以草坪为主,水体主要形式为湖泊和小溪。所有景观元素的设计必须体现使用、审美和生态三大功能的平衡。     

姚引良副省长作重要讲话 张社年厅长作工作报告 全省林业局长会议在西安召开

全省林业局长会议2月22日在西安召开。各市林业局、杨凌示范区农村发展局的主要负责同志、纪委书记，10个集体林权制度改革试点县主管林业的副县长、林业局长，15个“扩权强县”试点县林业局长，厅机关各处（室、局）主要负责同志、厅直属单位主要负责同志、纪委书记，省森林资源局领导班子成员、监审处长及所属单位主要负责同志、     

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.     

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.     

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。