银瓶山森林公园润楠属植物群落多样性研究

为了解银瓶山森林公园润楠属植物的群落组成、物种多样性及其与海拔因子的关系,对森林公园内不同海拔的12块样地进行调查研究,计算乔木层、灌木层和草本层的物种丰富度指数、Simpson优势度指数、Shannon-Wiener多样性指数和Pielou均匀度指数,分析群落物种多样性与海拔之间的相关性,结果表明:银瓶山润楠属群落中共有70种植物,隶属于41科58属.各植物群落的物种丰富度指数(S)、Simpson优势度指数(D)、Shannon-Wiener多样性指数(H')整体表现为灌木层＞草本层＞乔木层,Pielou均匀度指数(E)表现为草本层＞灌木层＞乔木层.不同群落的乔木层植物物种多样性沿海拔梯度呈先上升后下降的单峰模式,灌木层和草本层的物种丰富度指数、Shannon-Wiener多样性指数均表现为随着海拔的升高而逐渐下降的规律;Simpson优势度指数、Pielou均匀度指数未呈现明显规律.     

山东典型山地引种火炬松和日本落叶松的群落特征比较分析

选取山东典型山地(泰山、蒙山和昆嵛山)的11个样方,研究火炬松群落和日本落叶松群落的生长和更新,从种群特征、群落组成和物种多样性3方面评价适应性。结果表明:火炬松群落的乔木、灌木和草本植物种类分别为15种、29种和27种,植株密度分别为(15.38±1.84)株/dam2、(51.50±13.00)株/dam2和(14.38±3.80)株/m2;日本落叶松群落的乔木、灌木和草本植物种类分别为26种、49种和49种,植株密度分别为(10.55±0.97)株/dam2,(37.07±7.99)株/dam2和(25.45±11.35)株/m2。火炬松群落中主要乔木火炬松种群为稳定型、栓皮栎种群为显著增长型、麻栎种群和赤松种群为增长型;日本落叶松群落中主要乔木日本落叶松种群、花楸种群和椴树种群为稳定型,栓皮栎种群为显著增长型。火炬松群落物种丰富度指数和Shannon-Wiener多样性指数为灌木层草本层乔木层,Simpson多样性指数和Pielou均匀度指数为草本层灌木层乔木层;日本落叶松群落物种丰富度指数为灌木层草本层乔木层,Shannon-Wiener多样性指数和Simpson多样性指数为灌木层乔木层草本层,Pielou均匀度指数为草本层灌木层乔木层。火炬松群落演替趋势为火炬松林→针阔混交林→麻栎林或栓皮栎林,日本落叶松群落演替趋势为日本落叶松林→针阔混交林→栓皮栎林或杂木林。     

灵空山油松群落物种多样性研究

依据山西灵空山国家级自然保护区油松林群落的调查结果,研究了油松群落的物种组成,计算了各层次物种重要值,分析了物种多样性。结果表明:(1)在64个样地中发现了177种植物,其中乔木28种,灌木51种,草本98种,隶属于49科110属。(2)乔木层和草本层优势种更为明显。依各层次植物重要值排序,乔木层优势种为油松,草本层优势种为披针苔草,灌木层优势种为土庄绣线菊。(3)多样性指数在各层次表现为:灌木层多样性指数和均匀度指数最高,优势度最低;草本层的丰富度指数最高;乔木层的优势度指数最高,丰富度、多样性和均匀度指数均最低。     

赤皮青冈人工混交林物种多样性与种间竞争研究

为了解赤皮青冈的群落结构,预测其群落动态变化,对福建建瓯上元村赤皮青冈人工混交林进行植被调查,以物种丰富度、多样性指数、优势度指数和均匀度指数作为多样性测度指标对样地进行统计分析,采用Levins测度式和Lotka-Volterra竞争模型研究群落中优势树种的竞争关系。结果表明:样地内共有乔木20种,612株;灌木35种,249株;草本33种,1 364株;群落中灌木层物种丰富度最高,多样性指数、优势度指数和均匀度指数均为草本层灌木层乔木层;赤皮青冈在与杉木、栲树、木荷间的竞争均处于劣势地位,与钩栲、白花泡桐、青冈、木油桐间的竞争占优势。     

福建清流鄂西红豆人工林群落调查与物种多样性初步研究

通过样地调查法研究了福建清流鄂西红豆人工林群落植物组成与物种多样性。结果表明：清流鄂西红豆人工林群落共有维管束植物的数量为21科36种，其中乔木层树种有6科9种、灌木层树种有16科24种、草本层物种有5科5种。研究表明：清流鄂西红豆（Orosia hosiei Hemsl）人工林群落是以鄂西红豆为建群种，苦槠（Castanopsis sclerophylla）＋拟赤杨（Alniphyllum fortunei）＋枫香（Liquidambar formosana）为优势种的群落。清流鄂西红豆人工林群落不同层次的多样性指数、丰富度指数、均匀度指数均表现为灌木层＞乔木层＞草本层，而优势度指数为乔木层（0．878）＞灌木层（0．813）＞草本层（0．246）。     

福建光泽南方铁杉群落植物组成与多样性分析

采用样地调查法研究了福建光泽香炉山南方铁杉天然林群落植物组成与多样性。结果表明:光泽南方铁杉天然林群落(2000 m2)共有维管束植物27科40属52种。南方铁杉群落乔木层常绿树种占据优势,而灌木层常绿树种占据压倒性优势,说明常绿树种幼苗幼树耐阴性比落叶树种强,从而在林下低光照环境下具有更强的竞争能力。南方铁杉群落的乔木和灌木层发达,而草本层发育差,物种数与群落多样性指数均为灌木层>乔木层>层外植物>草本层;而均匀度则多为层外植物>灌木层>乔木层>草本层。南方铁杉种群幼苗幼树数量较多(2151株.hm-2),但小树数量极少(24株.hm-2),有一定数量的中树和大树(405株.hm-2)。南方铁杉幼苗幼树耐阴性差,难以与耐阴性强的常绿乔灌木树种竞争,这可能是南方铁杉濒危的原因之一。     

闽北杉阔混交林群落物种多样性的研究

应用物种丰富度指数、多样性指数、均匀度指数、种间相遇机率、生态优势度等多种指标,将杉阔混交林群落划分为乔木层、灌木层、草本层、层间层,对不同层次群落的物种多样性进行研究。结果表明:不同层次群落的物种多样性不同,总的趋势是灌木层>乔木层>层间层>草本层。乔木层物种丰富,但生态优势度高于灌木层,个体数量产生一定程度的集中,物种多样性低于灌木层;灌木层生态优势度最低,物种组成丰富,表现出最大的物种多样性;草本层植物物种组成简单,生态优势度最大,物种多样性最低;层间层植物物种数量低于草本层,但生态优势度也低于草本层,其物种多样性高于草本层。该群落中灌木层在保持群落多样性方面所起的作用最大。     

大关县3种筇竹群落生物多样性研究

对大关县乔木-筇竹群落、灌木-筇竹群落和筇竹-草本群落3种群落,采用二元属性数据测度方法进行了生物多样性的调查。结果表明:3种筇竹群落类型中以乔木-筇竹群落物种总种数(178种)为最多。各层次物种丰富度的顺序依次为,乔木-筇竹群落的物种丰富度为乔木层>草本层>灌木层;灌木-筇竹群落和筇竹-草本群落的物种丰富度一致,其物种丰富度顺序依次都为灌木层>草本层>乔木层。乔木-筇竹群落的乔木层的Shannon-Wiener(H’)指数最高,灌木-筇竹群落的灌木层和草本层的H’指数最高,筇竹-草本群落各层的H’指数都较低。灌木-筇竹群落与筇竹-草本群落在环境梯度上不同点之间的共有种最少,相似性最低,群落间的差异大,群落间物种替代速率较高。     

蒙山沟谷次生林群落结构和物种多样性

选取蒙山典型沟谷次生林,设置16个样方,分析群落结构和物种多样性。结果表明:1)蒙山沟谷次生林群落至少包括乔木层植物28种,灌木层植物39种和草本层植物49种,乔木、灌木和草本3种植物类型的个体密度分别为1.425株/m~2,8.892株/m~2和11.73株/m~2。28种乔木根据径级结构划分为12种扩展种、2种隐退种、6种稳定侵入种和8种随机隐退种;2)蒙山沟谷次生林主要乔木种群径级类型为两种,栓皮栎、麻栎、黄檀、槲树、朴树、君迁子和小叶朴为增长型,黑松和赤松为稳定型;3)蒙山沟谷次生林物种丰富度指数、Shannon-Wiener多样性指数和Simpson多样性指数从高到低均呈现为灌木层乔木层草本层,而Pielou均匀度指数则呈现为草本层灌木层乔木层。研究结果可为沂蒙山区乃至北方土石山提供科学依据和数据参考。     

闽北乐东拟单性木兰天然林群落结构与多样性

采用相邻格子法设置样地,对闽北邵武乐东拟单性木兰天然林群落结构与多样性进行研究。结果表明:以乐东拟单性木兰为优势建群种的天然林群落共有维管束植物42科63属86种;群落乔木、灌木层发达,而草本层发育差;群落中高位芽植物占优势(87.21%),而高位芽植物中,以小高芽植物比例最大,其次为中高芽;群落不同层次的物种丰富度(S)、Shan-non-Wiener指数(H')及其Pielou均匀度指数(Jsw)、Simpson多样性指数(D)及其Pielou均匀度指数(Jsi)均为灌木层乔木层草本层层外植物。乐东拟单性木兰种群有较多的幼苗幼树(2434株·hm-2),有一定数量的大树(75株·hm-2),但小树数量少(97株·hm-2),种群结构在中树阶段出现断层。虽然目前群落较稳定,但经过长期的演替,乐东拟单性木兰可能被其他更加耐阴的常绿阔叶树种所取代。     

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.     

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.     

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。