森林旅游景区生态安全影响因素的IRDS模型研究——基于扎根理论

运用探索性研究工具, 分析森林旅游景区生态安全影响因素及其关系; 借助经典扎根理论, 建立森林旅游景区生态安全影响因素分析的总体框架; 采用开放式访谈与多种类型研究资料, 经过概念化、范畴化等多重编码, 归纳出森林旅游景区生态安全影响因素的10个主范畴和35个范畴; 在此基础上, 根据上述范畴在原始资料中所呈现出的内在逻辑关系, 构建了由制度环境(I)、监管与建设行为(R)、干扰活动(D)、安全状态(S)4个范畴模块构成的森林旅游景区生态安全影响因素的IRDS模型, 并分析景区生态安全的影响因素模块(I, R, D)对其安全状态模块S的作用机理; 最后, 探讨了IRDS模型作为森林旅游景区生态安全研究的理论框架, 在彰显影响主体间角色关系, 强化风险源与状态、响应间关系, 以及提升不同尺度下研究结果普适性等方面的优势。     

我国森林旅游景区生态安全的IRDS分析

依据制度—监管—干扰—状态(IRDS)模型框架,分析我国一些森林旅游景区中资源环境质量明显下降、植被遭到不同程度损毁、动物受到惊扰和伤害等生态安全问题现状。探讨景区生态安全水平下降的关键致因:景区环境相关法规建设远滞后于景区生态环境保护需要、景区在发挥社会认证作用功能时存在选择性、监管主体在景区资源的使用与保护中存在过多利益纠葛、景区开发水平与资源保护水平之间的关系严重失调、景区管理者对景区生态安全的实际边界掌控能力不足、景区资源使用及参与主体间责利关系失衡。提出基于IRDS模型的以生态优先为导向的森林旅游景区生态安全良性循环发展模式、多元环境保护制度体系等措施的景区生态安全水平提升路径。     

千岛湖风景区旅游形象感知与满意度

为更好地规划和管理景区,文章以中国和加拿大的千岛湖景区作为典型案例进行比较,通过收集网络平台上的游客点评,采用内容分析法获得景区游客形象感知,对文本进行旅游要素编码及要素等级评定,通过IPA分析法获得景区在发展过程中的优劣势旅游感知要素。结果表明:游客对中国千岛湖感知主要集中在旅游地理位置、自然景观和基础服务设施3个方面,对加拿大千岛湖的感知则集中在地理位置、自然景观和人文景观3个方面;中国和加拿大千岛湖游客情感态度上都倾向积极,但也都存在一定的消极评论;中国、加拿大千岛湖景区24个旅游要素的重要性和游客的满意度情况显示加拿大千岛湖较中国千岛湖获得游客的认同更高;针对两景区的旅游感知要素水平提出相关建议,以期对景区之间相互学习、完善与提升提供参考。     

基于RS和GIS的天鹅山林场森林景观格局研究

以2003年12月28日Spot5遥感图像和2000年天鹅山森林二类资源调查数据为主要数据源,利用ERMAP-PER和ARCGIS为空间信息处理工具得到森林景观分布图,采用软件Fragstats3.3对天鹅山林场的景观要素特征、景观异质性和景观空间关系进行了分析,以揭示其生态状况和空间变异。结果表明:全场共划分7类景观要素,其中杉木林、阔叶林为该场主要森林景观要素类型;松林与幼林受人类干扰大而阔叶林受人类干扰小;杉木林地之间的聚集状况较好。     

基于文本挖掘的喀纳斯景区旅游认知、情感、整体形象研究

以新疆喀纳斯景区为例,基于旅游社交平台网络点评数据,利用ROST CM6软件提取喀纳斯景区旅游形象的高频特征词,采用内容分析法分析喀纳斯景区旅游认知形象和情感形象,获得了游客对喀纳斯景区旅游形象的感知。结果表明:游客对旅游景观认知词条比较单一,对喀纳斯景区的认知主要体现在以自然风光为核心的旅游吸引物上,景区内的人文景观关注度低。喀纳斯景区情感形象积极感知的主要方面集中在游客对旅游吸引物的积极感知;游客对服务管理类的消极感知构成了喀纳斯景区情感形象消极感知的主要方面。游客对喀纳斯景区整体旅游形象感知持积极态度,持消极态度的游客占比较低。     

森林景观类型环境耦合度模型的构建与应用

由于森林景观内部生物机制与外部环境相互作用,不同的森林景观类型存在生态功能流的传递与交换,在同一环境条件下,会因为其生物学特性的差异产生不同的相互作用.根据这种森林景观类型在环境适宜性测度上的相互作用的程度,借鉴生态系统的“生态位”,提出森林景观类型环境耦合度的概念,并建立了相应的模型.研究表明：（1）森林景观在环境资源利用上互相补充、互相干扰,从而衍发耦合.耦合可能会带来系统的进化,产生新的结构与功能.（2）耦合度大小反映了森林景观类型两两之间在同一环境条件下共生稳定的状态,但只反映整体稳定性效应.其稳定性从森林景观对环境适宜的两个方面来体现,即生态相似性与生态互补性.（3）当某一景观跨越一个渐变的环境梯度时,对耦合度模型的应用造成一定的复杂性.（4）由于不同的环境资源使同一森林景观体现不同的生存状态,以及对环境资源利用会呈现阶段性的变异,森林景观环境稳定的耦合状态的确切认定存在模糊性.     

云水谣历史古镇景区形象感知研究

文章以云水谣古镇为例,采用网络文本和IPA相结合的分析方法,在携程网、蚂蜂窝、大众点评网、去哪儿网、同程网、TripAdvisor等旅游网站上获取游客对景区的评价数据,使用GooSeekerv9.0.4软件在高频词汇分析、情感分析和语义网络分析的结果中构建分析模型,评价游客景区体验要素结构和体验质量,剖析基于网络数据的历史古镇景区形象感知。结果表明:游客对该景区体验要素的关注度相对集中;游客对该景区体验要素的重要性感知度差异较大;未来历史古镇景区可从景区内外部环境、景区热门景点、历史文化背景、活动策划项目、基础服务设施5个方面进行改进提升,从而为游客提供更高质量的游览体验。     

基于网络文本分析的杭州超山梅花节旅游形象感知研究

为了更加客观、真实地反映节庆期间游客对景区旅游形象感知,以杭州超山梅花节为例,通过网络文本分析法,把近4a梅花节期间游客在各大旅游网站上的评论和游记作为研究样本,以景区整体环境、景区旅游资源、游客行为活动、旅游设施服务作为游客旅游形象感知的构成元素,对游客关于梅花节期间景区的旅游形象感知进行研究。结果显示:游客对景区整体环境认知良好;认为景区对现有资源利用不充分;在对景区内开展的各项娱乐活动较为满意的同时认为景区旅游元素过于单一;对景区的旅游设施服务方面存在一定的消极感。在此基础上,提出了改善基础设施服务、充分利用现有资源、优化游客旅游体验等建议。     

人类干扰对森林景观类型相关性的影响研究

根据人类干扰对森林景观变化效果大小,把对森林景观产生作用的人类干扰类型分为调控型和变迁型,建立了定量评价人类干扰对森林景观类型相关性影响的综合测度模型.结果表明,人类干扰调整了森林景观的总体格局,改变了森林景观类型间的相关性;从森林景观与人工景观、管理景观的相邻度可以衡量人类干扰的影响程度;人类干扰因素的复杂性及各因素间的关联性,导致各因素对干扰机理存在模糊性,要进一步把握干扰影响的内在规律,必须结合其它方法.     

基于网络文本与IPA模型分析的上海共青森林公园旅游形象感知研究

在网络生活高速发展前提下,网络评论已经是获取目的地旅游形象感知的重要渠道。利用网络文本途径结合Rost Content Mining软件与IPA模型分析,展开对上海共青森林公园旅游形象感知的分析,得到高频词汇、情感分析及网络语义分析图。结合高频词汇与网络语义分析通过IPA模型进一步研究,总结出针对公园的游客旅游体验要素结构与体验质量评价结论。结果表明,游客对目的地的形象感知整体呈现积极的态度,各体验要素之间的分值存在差异。公园可从保持现有优势、改进设施管理水平、丰富活动、完善交通网等方面入手,全方位共同提升,为游客提供更优质的旅游体验。     

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。