湖南猛洞河河谷维管植物区系特征研究

对猛洞河河谷维管植物区系特征进行了研究,结果表明:猛洞河河谷共有维管植物129科、389属、670种(含变种),其中蕨类植物12科16属25种,裸子植物1科1属1种,被子植物116科372属644种;植物区系以热带性质为主,但温带性质明显,是一个从热带向温带过渡的区系,热带成分属占54.46%,温带成分属占40.06%;特有程度较高,有中国特有属19个,中国特有种有311种,武陵山特有种37种,猛洞河特有种5个;与同地域的区系相比,猛洞河河谷是本区域内泛热带、北温带、东亚分布和中国特有成分的重要分布区。与同类型的河谷区系相比,猛洞河河谷的泛热带成分低于干旱河谷,但高于干暖、干热河谷,温带成分均高于干热、干暖和干旱河谷。此外,中国特有分布属较其它类型的河谷占绝对优势。     

川西雅砻江上游地区种子植物区系研究

雅砻江上游地区地处青藏高原东南部,横断山区西北地带,在中国植物区系划分中属于泛北极植物区,中国-喜马拉雅森林植物亚区中的横断山脉植物地区.该流域种子植物有81科,共有8个分布型6个变型,世界分布有35科,占雅砻江上游地区总科数的43.2%;热带分布有23科,占该流域总科教的28.4%,其中以泛热带分布科为主,有14科(含有3科分属两变型),占该流域热带总科数的60.9%;温带分布共有23科,占该流域总科数的28.4%.其中以北温带分布占绝对优势,有20科(含有13科分属两变型),占该流域温带总科数的87.0%.种子植物属可划分出15个类型,18个变型,分别占中国15个分布区类型和31个分布区变型的100%和58.1%,体现出了该流域种子植物属的区系地理成分的复杂性和多样性,温带分布有298属,占该流域总属数71.1%,其中以北温带分布占绝对优势,有141属;排第二位的是东亚分布,共有52属,中国-喜马拉雅成分就占了33属;排第三位的是旧世界温带分布,有50属;中国特有属有15个,占该流域总属教的3.6%.统计结果显示:热带成分的科和温带成分的科相当;种子植物属的区系以温带成分为绝对优势,并与热带区系具有一定的亲缘关系,其东亚成分以中国-喜马拉雅区系为主,具有显著的特有性.     

薛公岭自然保护区种子植物区系研究

山西薛公岭省级自然保护区共有种子植物74科352属769种。种子植物属的区系分布类型较为丰富,其中,温带分布成分占绝对优势(温带分布成分共241属,占总属数的79.82%)。种的区系分布类型中,以中国特有分布成分占绝对优势(中国特有分布成分共291种,占总种数的38.14%)。对属、种区系成分与植被关系的分析表明,薛公岭自然保护区种子植物具有暖温带落叶阔叶林地带性区系成分的特点。在薛公岭自然保护区主要植被类型的建群种和优势种组成中,中国特有成分占明显优势。薛公岭自然保护区有国家二级保护植物1种——野大豆,有山西省重点保护植物党参、文冠果、刺五加、山核桃。     

广西木本植物区系的基本特征

根据野外调查和相关资料整理,对广西木本植物的区系组成、区系地理成分、生长型和特有种进行统计分析。结果表明:广西木本植物区系组成十分丰富,共有3 537种,隶属于147科,760属,其中蕨类植物1科、1属、6种,裸子植物8科、18属、60种,被子植物138科、741属、3471种。这些种类中以乔木种类最多,有1 512种,占到42.75%,而木质藤本植物最少,只有637种,占18.01%。广西木本植物区系的性质具有明显的热带-亚热带性质,表现出热带向温带过渡的特点,并具有热带北缘的特点。特有种类和重点保护种类较多,有广西特有种302种,国家重点保护植物86种,广西重点保护植物78种。     

东营市植物资源调查与区系分析

东营市自然分布的维管束植物共有87科279属501种,其中蕨类植物4科5属8种、裸子植物1科1属1种、被子植物82科265属492种;含有20种以上的大科有禾本科、菊科、豆科、莎草科和蓼科。属的地理成分可归为14个分布区类型,其中世界分布67属,而且多为典型植被草甸、沼泽和水生群落的优势种和建群种。剔出世界广布成分后,温带区系成分占63.21%,热带区系成分36.79%。就具体区系成分而言,北温带分布最多,71属占33.50%,其次是泛热带分布,50属占23.58%,再次为旧世界温带成分,31属占14.62%。东营植物区系的地带性特征不显著,植物区系虽然表现出温带特征,但东亚成分与同纬度其他地区相比偏少,中国特有成分贫乏。     

浙江丽水白云山森林公园野生藤本植物区系

为了解野生藤本植物区系的特点,采用野外调查与资料查阅相结合的方法,对公园内的藤本植物进行调查和区系分析。结果表明:白云山地区野生藤本植物有32科77属183种(含种下分类群)。分别占白云山野生种子植物的21.77%、13.23%、15.63%。属水平上,本区以单种属和寡种属为主,分布类型以泛热带占优势(28.60%),其次是东亚分布(14.29%),热带亚洲分布也占据了一定的比例(11.70%);种水平上,种的分布类型以中国特有种为最多(59%),其次是东亚分布(16.40%)、热带亚洲分布(15.30%),其余类型为零星分布。按照区系分区标准,将中国特有种分为7个亚型,其中以华东-华中-华南分布最多(57种)。可见,白云山地区藤本植物种类丰富,地理成分复杂多样,拥有较多的特有植物。可以为本市的绿化提供材料。     

庆阳木本植物多样性和区系特征分析

通过对甘肃庆阳市木本植物种类进行调查研究及多样性和区系特征分析,结果显示:林木种质资源690种,分属76科、177属;科的地理成分热带分布占比为40.8%,温带分布占比31.6%,世界广布占比25%,中国特有科占比2.6%;属的地理成分体现出温带分布高达62.7%,热带成分占比27.7%,世界广布占比5.1%,中国特有占比4.5%;热带分布科占优表现了庆阳温带植物区系具有热带亲缘,温带属分布占比高说明了庆阳木本植物物种区系分布的温带属性;同时表明了庆阳植物区系具有物种多样性丰富度较高、区系成分复杂多样、联系广泛、有显著的温带性质和热带亲缘及强烈的过渡属性。     

四川九顶山自然保护区植物区系研究

通过对九顶山自然保护区植物群落野外调查,经鉴定有高等植物175科665属1 790种。通过植物区系成分分析,该区区系复杂,具有15种分布类型。区系具有以下特征:明显的温带性质,温带成分328属,占总数的59.2%,尤其以北温带分布为主(166属);中国特有属多,18属19种;与热带有一定亲缘关系,热带成分158属,占28.5%;区系起源古老,多单型、少型属。     

甘肃省荒漠种子植物属的区系分析

对甘肃省荒漠区种子植物属的组成及其区系特征进行了研究.结果表明:甘肃省荒漠区分布有种子植物228属,其区系特征为单种属和寡种属多,优势现象明显,植物区系具有温带荒漠性和古老性;区系地理成分复杂多样,包含9个分布区类型和13个变型,温带成分(包括北温带分布及其变型、旧大陆温带分布及其变型和温带亚洲分布)占有绝对优势,占总属的33.76%;地中海区-西亚-中亚分布也是主要的组成部分,占总属的28.98%,特有成分比较低,中国特有成分仅4属,只占总属数的1.57%,起源古老,多为本土发生.     

山东木质藤本植物区系分析

山东省野生木质藤本植物共有63种(包括变种和亚种),隶属于27属21科。区系成分分析表明其基本特点是:全为被子植物,双子叶植物科属种最多;小型科属较多,而大型科属较少;各类温带成分占54.2%,而热带成分占33.3%,表明本区系为暖温带性质;特有现象不明显。     

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.     

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.     

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。     

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.