金殿滇油杉群落物种组成、生态位及滇油杉种群动态分析

对滇中高原昆明金殿滇油杉群落进行了调查,分析其物种组成和各主要物种生态位,并绘制了建群种滇油杉的生命表和存活曲线。结果表明,昆明金殿滇油杉群落共有种子植物70种,隶属38科63属。生活型分析表明高位芽植物占比最大,为60%,说明该地区气候大多时候是温湿型。科属的区系分类结果表明滇油杉群落以热带科和温带科为主,其中热带科最多。属则以温带属最多,热带属次之。表明滇油杉林的区系成分以热带起源为主,属于亚热带植被即暖温性针叶林。生态位的宽度重叠结果表明,在乔木层、灌木层、草本层中具有最宽生态位的物种分别为滇油杉、小铁子和紫茎泽兰。各层重叠宽度主要集中在0.38~0.70、0.00~0.57和0.14~0.97之间。这表明灌木层各物种生态分化较大,可能对群落物种共存有重要作用。滇油杉生命表和存活曲线表明,当滇油杉种群在达到既定年龄,即位于龄级8后死亡率才明显增加。     

云顶山自然保护区植物群落物种多样性研究

以野外调查的数据和植物群落TWINSPAN分类结果为基础,应用丰富度指数、多样性指数和均匀度指数等物种多样性指数对山西云顶山自然保护区植物群落的物种多样性进行了研究。结果表明:(1)其植物群落13个群丛R0、H′、E_1和E_5的变化趋势基本一致,物种多样性指数综合排序为:群丛Ⅱ群丛Ⅴ群丛Ⅸ群丛Ⅹ群丛Ⅳ群丛Ⅵ群丛Ⅷ群丛Ⅺ群丛Ⅰ群丛Ⅲ群丛ⅩⅢ群丛Ⅶ群丛Ⅻ。(2)森林群落中白杄+华北落叶松–土庄绣线菊+金银忍冬–披针叶苔草+小红菊群丛多样性指数最高,华北落叶松+白桦–金银忍冬–披针叶苔草群丛多样性指数最低;灌丛群落中美蔷薇+刺梨–野青茅+东方草莓群丛多样性指数最高,沙棘+黄刺玫–山蒿+水杨梅群丛多样性指数最低;草本植物群落嵩草+平车前群丛多样性指数比委陵菜+早熟禾群丛高。(3)不同群落类型间的物种多样性指数差异显著(P 0.05),其中森林群落最高,表明群落结构越复杂,物种多样性指数越高。     

草海湿地流域典型喀斯特森林群落α、β多样性分析

选择草海湿地流域典型喀斯特森林植物群落作为研究对象,采用标准样地调查法、群落数量分析等方法,对其不同群丛、群落、层次的森林物种多样性进行分析,结果表明:(1)α多样性分析中,群丛Ⅶ(云南松-栒子+白栎—荩草+芒群丛)的Margalef丰富度和Simpson多样性最高,而群丛Ⅳ(云南松-白栎+云南杜鹃—密毛蕨+莎草群丛)的Shannon-Wiener多样性和Pielou均匀性最高;群落B(阴坡、低海拔、陡坡群落类型)的Margalef丰富度最高,群落D(阴坡、高海拔、缓坡群落类型)的Simpson多样性最高,群落A(阳坡、高海拔、缓坡群落类型)的Shannon-Wiener多样性和Pielou均匀性最高。(2)β多样性分析中,群丛Ⅰ(云南松+马缨杜鹃-矮杨梅-野鸭茅群丛)—Ⅱ(华山松+云南松-矮杨梅+云南杜鹃-密毛蕨+白茅群丛)的β多样性最高;群落A(阳坡、高海拔、缓坡群落类型)-D(阴坡、高海拔、缓坡群落类型)的β多样性最高。     

紫茎泽兰入侵受松小蠹危害的云南松林群落的研究

探讨了紫茎泽兰对松小蠹危害成灾云南松林的入侵状况,对3个受灾云南松群落的结构、生物多样性指数、紫茎泽兰的入侵危害程度进行了研究,分析了松小蠹危害与紫茎泽兰入侵的相互关系.结果表明:松小蠢危害可通过影响群落结构而导致生境变化,增加了群落的可入侵性.群落结构越简单,生物多样性水平越低,对生境资源的利用越不充分,紫茎泽兰成功入侵的机会越大.松小蠹的危害导致云南松林退化,紫茎泽兰的入侵加剧了其生态系统的退化过程,成为影响森林生态系统健康状况的重要生态过程之一.     

鄱阳湖平原湖泊水生植物群落的多样性

研究了鄱阳湖平原湖泊水生植物群落类型多样性、群落物种多样性指数、群落盖度与生物量,探讨了主要优势种的繁殖策略及多样性保护的有效途径.结果表明:鄱阳湖平原湖泊现有水生植物群丛42个,其中湿生植被群丛11个、挺水植被群丛6个、浮水植被与沉水植被群丛分别为11和14个;在湿生类型中,分布面积最大的群丛为灰化苔草群丛,其次是"荻+芦-灰化苔草群丛"和"艹鬲鸟草+马蓝群丛";在沉水类型中,分布面积最大的是密齿苦草群丛,其次为菹草群丛、"竹叶眼子菜+穗花狐尾藻群丛"与"野菱+双角菱群丛";群落物种多样性指数最高的是"野菱+双角菱群丛"与"菰+野菱群丛",其次为"野菱+双角菱-密齿苦草群丛"和菰群丛;在所有群丛类型中,以灰化苔草群丛的盖度最大,以菰群丛的生物量最高;有效的繁殖策略是灰化苔草、密齿苦草、菹草等主要优势种在强烈的人为干扰压力下依然分布广阔的根本原因;多样性保护的有效途径是政府部门的行政干预和经费投入.     

缙云山草珊瑚群落植物物种多样性研究

采用双向指示种分析法，将缙云山草珊瑚生存群落分为7个群丛，并论述了各类型的特征。采用样方法统计分析其多样性，应用丰富度指数（R1）、Shannaon—Wiener指数（H’）和均匀度指数（E1）研究7个群丛的植物物种多样性。结果表明：1）草珊瑚生存群落共有维管植物45科79属104种；2）群丛植物物种多样性指数的大小受立地生境和人为活动的综合影响，群丛间植物种多样性的平缓变化表明7个群丛对缙云山亚热带季风气候具有相似的适应性；3）依据草珊瑚生存群落物种多样性的大小对7个群丛进行排序后发现立地条件好，人为干扰小的群丛其物种多样性相对较高。4）用H’指数、λ指数和E1指数描述群丛性质时存在较好的一致性，入指数和H’指数可较好地测度优势种在群丛中作用的大小。     

湖北远安县湿地植物多样性及群落数量特征研究

采用野外湿地样方调查及结合文献资料,选择物种多样性指数,研究了湖北远安县湿地植物多样性、区系特征、主要群落类型及数量特征。结果表明：远安县湿地植物有108科264属360种,科级区系分布类型可划分为7类5种变型,以世界广布和热带分布型为主,温带分布类型较少,中国特有类型仅1科。县域范围内分布的典型湿地植物群落54种,群落物种多样性指数中,Patrick指数均值为18.80±5.19;Shannon-Wiener多样性指数均值为2.15±0.39;Simpson优势度指数均值为0.81±0.10;Pielou均匀度指数均值为0.75±0.10;Margalef指数均值为3.44±0.87。鬼针草群丛的Patrick指数与Margalef指数最低,竹叶眼子菜群丛的香农多样性指数、Simpson优势度指数、Pielou均匀度指数最低;芋群丛Patrick指数最高,乌桕群丛Pielou均匀度指数最高,加杨群丛香农多样性指数和Simpson优势度指数最高,白饭树群丛Margalef指数最高。该研究结果可为远安县及类似地区湿地生态系统保护修复及湿地资源管理提供了基础资料和科学依据。     

福建光泽江南油杉群落结构与植物多样性

通过对福建光泽江南油杉群落结构与植物多样性进行调查与分析,结果表明:江南油杉群落(2 000m2)有维管束植物48科72属92种;江南油杉群落以高位芽植物占据优势(80.44%),生活型谱具有典型的中亚热带气候特点;群落径阶和树高结构复杂,物种多样性丰富,不同层次物种多样性指数和均匀度指数均为灌木层乔木层藤本层草本层,体现了的亚热带常绿阔叶林的典型特征;群落中江南油杉在乔木层占绝对优势,但幼苗幼树数量较少,在灌木层受到其他植物(主要是木本植物)的强烈竞争,种群有衰退的趋势。     

中条山栓皮栎林数量分类研究

基于群落学野外调查,应用TWINSPAN和DCA分别对中条山太宽河自然保护区栓皮栎(Quercus variabilis)林进行了数量分类和排序研究。结果表明:将中条山太宽河栓皮栎林的42个样方分为8个群丛,分别是:I.栓皮栎+槲栎-陕西荚蒾+连翘-披针叶苔草群丛,Ⅱ.栓皮栎+橿子栎-连翘+卫茅-披针叶苔草群丛,Ⅲ.栓皮栎+板栗-连翘-披针叶苔草群丛,Ⅳ.栓皮栎+板栗-连翘-披针叶苔草+矛叶荩草群丛,Ⅴ.栓皮栎-黄栌+连翘-披针叶苔草+野青茅群丛,Ⅵ.栓皮栎-黄栌-披针叶苔草群丛,Ⅶ.栓皮栎+槲栎-荆条+连翘+黄栌-披针叶苔草+委陵菊群丛,Ⅷ.栓皮栎+槲栎-连翘+榛子-披针叶苔草+细叶沙参群丛。群落和优势种的DCA排序结果表明:影响群落分布和优势种分布的生态因子主要是热量和水分。     

贵州百里杜鹃景区植物群落多样性与稳定性研究

百里杜鹃是全球同纬度范围内中低海拔区已知面积最大的天然杜鹃林。为了解其主要植物群落的物种多样性和群落稳定性,选取景区内的马缨杜鹃林(Form.Rhododendron delavayi)、露珠杜鹃林(Form.Rhododendron irroratum)、杜鹃混交林(马缨杜鹃+露珠杜鹃林)(Form.Rhododendron delavayi+Rhododendron irroratum)和杂木林(茅栗+白栎林)((Form.Castanea seguinii+Quercus fabri))等4种主要群落,采用α多样性指数、M.Godron方法分别测定其物种多样性和稳定性。结果表明:1)4种群落物种丰富度从高到低依次为杂木林(茅栗+白栎林)>杜鹃混交林(马缨杜鹃+露珠杜鹃林)>马缨杜鹃林>露珠杜鹃林;2)Simpson指数、Shannon-Wiener指数和Pielou均匀度指数在不同群落的乔、灌、草3个层次变化规律不一致,多样性指数均以露珠杜鹃林最低;3)4种群落仅马缨杜鹃林呈稳定状态,以杂木林(茅栗+白栎林)群落最不稳定。各群落不同层次中,最不稳的为露珠杜鹃林的草本层。     

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.     

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.     

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。