对我省森林旅游业的思考

旅游业是一项综合性产业,它能通过产业联动链带动一系列相关产业如交通业、餐饮业、加工业、种植业、零售业等的发展。据研究,旅游业每收入1元,就给国民经济的相关行业带来5-7元的增值效益。目前,森林旅游作为旅游业的重要组成部分,已成为人们现代生活的一个重要内容,它顺应了人们回归自然的心理需求。开展森     

绿色旅游和观光农业

旅游业一直被称为“无烟工业”、“朝阳产业”，是我国改革开放以来国民经济各产业中发展最快的产业之一。在人们回归自然奔赴乡村的时候，绿色旅游已成为现代旅游的重要形式。一般而言，旅游就是发生在自然环境中的各种活动的总称。近年来我国旅游业发展十分迅猛，市场潜力巨大，因此许多城市已经把发展绿色旅游业作为城市发展战略的重要组成部分。     

四川发展生态旅游的对策

旅游业是当今世界上发展速度最快、发展势头最强劲的产业之一。无论是工业化国家还是发展中国家,旅游业作为重要经济支柱的地位不会改变。生态旅游作为实现旅游业可持续发展的重要内容,已成为极有生命力和发展潜力的旅游形式。     

咸宁市旅游业现状分析及发展对策

旅游业作为一项关联性极强的产业,通过带动其他产业的发展来加快整体经济发展具有重要作用.咸宁市具有发展旅游业优厚的条件,经济至今在湖北省内仍处于较落后的地位,如何通过发展旅游业来加快实现跨越式发展是一个值得探讨的课题.通过叙述咸宁市旅游业的现状,分析阻碍其发展的因素,提出相应对策.     

四川在生态旅游发展中展宏图

生态旅游是一项复杂的系统工程。对林业而言,是一个有着巨大潜力的新生事物。四川省委、省政府将旅游业作为全省经济社会发展的一个重要抓手,发展很强劲。据统计,2005年1￣10月,全省旅游收入已达到650亿元,预计全年将突破700亿元。四川旅游业的发展有两张王牌:一张叫自然生态,另一张叫历史文化。“生态是基础,文化是灵魂”。现在四川旅游业主要还是依托生态资源,自然生态这张牌在整个旅游业收入中占70%左右。旅游业作为全省的重点产业,生态在其中扮演了重要角色。从省到各地党委、政府都高度重视生态旅游,都加大了工作力度,推动生态旅游业的…     

从经济学角度看生态旅游产业发展

生态旅游是针对旅游业对环境的影响而提出的一种新的旅游形式，这种形式在短短十几年的时间内风靡全球，占据了世界旅游市场份额的30％以上，已成为一个迅猛发展的产业，在带动经济发展方面发挥着越来越重要的作用。     

绿色旅游和观光农业

旅游业一直被称为“无烟工业”、“朝阳产业”,是我国改革开放以来国民经济各产业中发展最快的产业之一。在人们回归自然奔赴乡村的时候,绿色旅游已成为现代旅游的重要形式。一般而言,旅游就是发生在自然环境中的各种活动的总称。近年来我国旅游业发展十分迅猛,市场潜力巨大,因此许多城市已经把发展绿色旅游业作为城市发展战略的重要组成部分。     

山东省蓝色经济区旅游产业协同发展研究

指出了在旅游业区域竞争激烈的时代背景下,区域旅游协作是区域经济发展的必然趋势,蓝色经济区旅游产业协作是一项重要的区域发展战略,大力发展旅游业对推动山东半岛社会经济的持续、健康、快速发展有着极其重要的作用.在分析蓝色经济区旅游发展现状的基础上,对区域旅游协作的必要性和旅游产业要素进行了论述,并从区域协作、管理协作、产业协作和企业协作四个方面提出了一些促进区域旅游协作的措施.     

关于相持阶段的林业产业发展问题——在林业产业建设专题研究班上的讲话

当前，我国生态建设已经进入了“治理与破坏相持阶段”。这一阶段的林业发展，是以满足国民经济发展需求、服从并服务于构建和谐社会目标、以生态建设为主的全新发展。在这一阶段，林业产业要不要发展？林业产业怎么样发展？已经成为当前林业行业和社会各界普遍关注的热点问题，也是相持阶段林业发展所面对的一个重要课题。下面，我就相持阶段林业产业发展的问题，谈几点看法，供大家参考。     

以建设生态省为契机促进海南西部旅游业跨越式发展

旅游业作为朝阳产业，正在蓬勃发展。当前，作为旅游业一重要分支的生态旅游已成为旅游事业发展的新时尚．西部旅游业尤其是生态旅游业的发展如何，将直接影响海南生态旅游业的发展，加快发展海南生态旅游业，不但是海南产业发展的要求，也是建设海南生态省战略目标和把海南建设成为中华民族的四季花园和全国人民的度假村的战略需要。为此，有必要分析海南西部旅游发展现状及存在问题，并提出今后的发展策略和主要措施。     

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.     

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.     

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.     

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。