藏东南发展生态旅游业的SWOT分析

分析藏东南发展生态旅游业的优势有：①地处大香格里拉生态旅游区核心地带;②藏传佛教文化丰富;③旅游资源丰富;④相关配套产业长足发展;⑤气候宜人．劣势有：①生态环境脆弱,自然灾害多发;②对外开放程度低;③专业人才匮乏．机遇有：①实施西部大开发,青藏铁路通车;②旅游业快速发展;③交通条件改善．挑战有：①生态旅游发展与生态保护的矛盾;②周边地区生态旅游业快速发展引起的客源分流．论述了藏东南生态旅游业的发展战略：资源开发与生态环境保护并重,提倡政府主导型旅游,打造生态旅游品牌等．     

我国西部地区生态旅游开发与利用

生态旅游是实现旅游业可持续发展的有效形式。西部地区旅游资源独特而丰富,是我国旅游业发展的主要后劲所在,西部大开发,为西部地区生态旅游业带来了千载难逢的机遇。加快西部地区生态旅游业,对促进西部地区经济发展具有深远的战略意义。一、西部地区生态旅游资源概述我国西部地区沙漠化土地面积较大,这些地区是生态脆弱区,具有着极为丰富的旅游资源,并以其多样性和独特性而著称,具体而言,中国西部地区旅游资源主要有以下几个方面:1.天然旅游资源面积大,品类多样,景观奇特。西部地区由于特定的自然条件和地貌类型,天然旅游资源十分丰富。广…     

泉州湾湿地生态旅游资源保护与开发刍议

泉州湾湿地是我国东南沿海典型湿地类型之一,其特殊的地理、自然条件和人类长期活动形成独特的湿地旅游资源,湿地多样性明显,但也伴随人为强度干预导致的景观脆弱性。为此,本文提出泉州湾湿地的保护和开发思路:①进行泉州湾湿地资源的本底调查,申报国家级湿地自然保护区;②制定湿地生态旅游发展规划,并逐步建立和完善生态旅游服务网络体系;③政府决策与社区参与相结合;④加强湿地旅游管理和环境影响评价。总之,泉州湾湿地旅游开发必须定位在生态旅游资源的保护开发,改变以往只重视其生产功能而忽视其生态、社会、文化功能的倾向,实现湿地资源的可持续利用。     

西部生态旅游开发模式探讨

西部地区有丰富的旅游资源及生态旅游业的发展优势.该文通过对西部生态旅游现状和存在问题的讨论,对预测生态旅游发展趋势的分析,提出了西部生态旅游的一些开发模式和发展理念,为实现西部旅游业的可持续发展提供了建议.     

鼎湖山生态旅游深层次开发策略

鼎湖山有得天独厚的生态旅游资源等待开发。作者根据鼎湖山生态旅游业的现状，提出了鼎湖山生态旅游深层次开发的设想，应以森林旅游为龙头，形成主题丰富的森林旅游产品；同时应着力开发文化生态旅游及土特产生态旅游系列产品。并从生态旅游规划，资源保护与管理、生态旅游产业、生态教育和市场促销等角度提出了建设性的建议。     

广东西樵山国家森林公园生态旅游现状及其发展对策

广东西樵山国家森林公园是珠江三角洲重要的生态旅游地,自然地理环境独特,旅游资源丰富多样,旅游业已初具规模;西樵山国家森林公园的可持续发展对当地经济发展和生态环境保护具有双重战略意义;分析西樵山国家森林公园生态旅游开发的条件和优势,以及目前生态旅游资源开发中存在的问题,提出西樵山国家森林公园生态旅游可持续发展的对策和建议.     

藏东南自然保护区资源利用模式研究

自然保护区资源利用问题一直是阻碍保护区持续健康发展的主要因素。寻求能兼顾发展和保护双重目标的资源利用方式,对提高资源利用效率、加快经济发展步伐至关重要。以藏东南工布自然保护区自然资源的利用为调查对象,通过对保护区自然资源的分类与利用形式的分析,提出保护区资源的分类管理和生态旅游发展模式,实施资源保护;发展特色优势产业;做大做强生态旅游业;走社区共管的发展道路等藏东南自然保护区可持续发展对策。     

藏东南生态旅游资源及其开发利用

就生态旅游资源的内涵进行了探讨。根据杨桂华的分类系统作了一些改动后,提出了新的生态旅游资源分类系统,在此基础上对藏东南生态旅游资源进行了分类。对藏东南生态旅游资源作了综合评价,认为该区自然景观丰富多彩、人文景观深邃独特、自然和人文景观相互辉映。指出该区生态旅游资源的开发原则应为:保护第一、参与性、适度开发与和谐,并作出了旅游开发项目设计。     

河南省生态旅游资源状况及开发的简要评价

生态旅游资源是发展生态旅游业、开展生态旅游活动的基础条件。河南省生态旅游资源类型多样而丰富,品位高且结构好;文物古迹类和自然风光类结构并重;具有一批世界级和国家级吸引力的资源,许多文化旅游资源属于绝品资源,具有较为明显的唯一性和垄断性。旅游收入的增加,使旅游业成了河南许多地方的支柱产业,为当地经济发展做出了重要贡献,但旅游资源的开发也对生态环境造成了不小的影响,如对植被、野生动物、水体、土壤、食物链等都造成不同程度的破坏。所以我们在进行生态旅游资源开发中应坚持开发和保护并重的原则,树立资源开发的整体意识,对全省生态旅游资源进行整合,将开发对生态旅游资源的影响降到最低,达到资源的可持续利用。     

浅议河南省自然保护区生态旅游发展

随着旅游业环保意识的增强,生态旅游已经成为当今世界旅游发展的主要趋势。河南省自然保护区类型多样,生态旅游资源丰富。为进一步促进河南省生态旅游的快速发展,在阐述河南省生态旅游资源概况的基础上,分析全省生态旅游的现状和问题,并对河南省自然保护区生态旅游开发提出相应的建议。     

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.     

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.     

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.