小五台山国家级自然保护区植被垂直分布特点

为了查清河北小五台山国家级自然保护区内的植被垂直分布特点,于2016~2017年期间,采用样线法调查记录了保护区植被垂直分布。结果表明:植被从山顶到山体基部有规律的分布,依次为:亚高山草甸带、亚高山灌丛带、针叶林带、针阔混交林带、落叶阔叶林带、人工油松林带、次生灌丛带、农田林果带。基本查清了小五台山国家级自然保护区的植被垂直分布特点,为保护区生物多样性的保护和科学管理提供依据,以促进其向顶级森林群落顺利演替。     

河北小五台山国家级自然保护区昆虫垂直分布与植被垂直带谱间的关系

为了解掌握河北小五台山国家级自然保护区昆虫垂直分布与植被垂直带谱间的内在关系,在多年野外实地调查,采集制作近万份植物和昆虫标本,拍摄上万张野外植物、昆虫的生态生境照片的基础上,对标本进行分类、统计、分析,对照其采集地的生态因子和生境特点,总结昆虫分布规律和特点,找出昆虫垂直分布与植被垂直带谱间的相关性。结果显示:昆虫垂直分布的果林-落叶阔叶林带大致对应植物垂直分布带的农田果林次生灌草林带至针阔混交林带,针阔混交-针叶林带大致对应针阔混交:林带至针叶林带、亚高山灌丛-草甸带大致对应亚高山灌丛带和亚高山草甸带。发现昆虫分布的垂直带谱与植物的垂直带谱之间有明显的相关性,但带与带之间也有一定的过渡阶段,他们之间存在内在联系,不是截然分开的,这主要源于大部分昆虫赖以生存的物质基础——食料因素。     

长白山 蘑菇垂直分布

正长白山地势高低悬殊,地貌、气候、土壤、植被等与平原地区、一般山地明显不同,这些因素相互联系、影响、制约,从山下(海拔500米以下)到山顶(海拔2100米以上)很有规律地垂直分布着几千公里范围才能见到的森林景观:阔叶林带、针阔混交林带、针叶林带、岳桦林带4个森林植被带,从而在蘑菇的分布上也带来了较为明显的垂直分布带。立体审视,     

长白山的生态价值

长白山位于北半球42度左右，在同纬度地区有美国的落基山和欧洲的阿尔卑斯山，但长白山的植被垂直分布带较为精彩。美国落基山和欧洲阿尔卑斯山的地形与土壤变化都较为复杂，因此它们的植被垂直分布带没有长白山上的植被分布有规律．而且它们的森材睹B以针叶林为主，树种组成简单，没有岳桦林带。岳桦树在两方被称为“金桦”，     

中国高山是壮美的自然画卷

<正>山地生物多样性因生态环境复杂,有水平、垂直,还有坡向的三度空间变化,加以地质变迁的影响,它的变化是四度空间的。山地对物种分布的影响可以从4个角度归纳:1.山地能接纳较多的物种。物种的水平分布向山地延伸时多转变为垂直,在一个水平空间内可有多个垂直带重叠,由于垂直带的阻限作用比水平带小,物种垂直分布迁徙可在短距离(时间)内完成,常出现物种分布的跨带与垂直带生态分布互补现象。生态适应互补现象以夏季黄山     

珍惜自然遗存 保护生态环境

长白山是欧亚大陆北半部最具代表性的自然综合体,是中国松花江、图们江、鸭绿江的共同源头,也是维系东北亚区域可持续发展的生态屏障。它拥有东北亚地区惟一完整的高山冻原带,是欧亚大陆从中温带到寒带主要植被类型的缩影,是不可多得的"生态博物馆"和"物种基因库",是世界上在最小范围内植物带垂直分布最明显、垂直分布类型最多、生物种类最丰富的特殊生态系统。地质构造的     

小五台山蜘蛛的垂直分布

于2007年对小五台山西台北坡按植被带垂直划分进行分带采集,结合近几年的鉴定记录,有明确海拔和生境记录的蜘蛛共172种.以此之为样本进行分析,结果表明,低山带组的蜘蛛种类最多,丰富度最大,而中、高山带组种类少;单带分布的种类数量明显大于跨两带和跨三带分布的种类.     

墨脱

<正>西藏墨脱国家级自然保护区的地貌、气候反差大,拥有较完整的垂直自然带分布,造就了由高向低,从高山冰雪带到低河谷热带季风雨林带的罕见景观。     

太白山林木真菌病害的垂直分布

我们对秦岭主峰太白山的林木真菌病害的分布规律进行了多年的探讨,结果表明,太白山林木真菌病害可划分为四个垂直分布带。即低山、低中山阔叶林叶点霉病和白粉病分布带;中山、高中山阔叶林锈病和立木腐朽分布带;中高山针叶林散斑病分布带;高山灌丛漆斑病分布带。     

雾灵山动物垂直分布

该文从两个角度研究了雾灵山动物垂直分布,一是垂直带动物分布,揭示的是各海拔段分布着哪些动物.低山带动物最多,达到133种,占总种数的77.3%;中山带与低山带接近,有128种,占总种数的74.4%;亚山顶带62种,占总种数的36.0%;山顶带只有10种,仅占总种数的5.8%.二是各种动物活动的海拔区域,揭示的是各种动物...     

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。     

森林冠层结构与功能及其时空变化研究进展*

林冠是森林与外界环境相互作用最直接和最活跃的界面层 ,同时 ,它本身又承载了森林生物多样性的主体部分。森林冠层研究的方法和技术在近些年取得了长足发展 ,从而促进了有关林冠结构与功能的研究。这些研究深化了人们对于林冠结构与光能截获以及群落干物质积累之间关系的认识 ,同时 ,对于森林冠层的物质循环和能量传输以及冠层内各营养级之间相互关系动态也有了更为深入的理解。考察森林冠层的结构与功能及其时空变化是深入理解整个森林生态系统的格局、过程及其运作机制的重要基础。     

Persistence of herbicides in forest nursery soils

The persistence of the four herbicides atrazine, hexazinone, lenacil and linuron was studied in forest nursery soils. The adsorption capacities of the soils for the chemicals were described by the distribution coefficients kj and k_oc. Due to the low content of organic matter in the soils the k_a‐values were low, in several cases being <1 for hexazinone. Hexazinone also had the lowest k _oc‐value (30) while the other substances had k_oc ‐values within the range 200–400. In some cases hexazinone showed great mobility under field conditions. The formula c=c_o‐kt^1/2 was used to describe the disappearance of the herbicides from the various soils. The rate of degradation of the four herbicides correlated well with the rate of respiration in the same soils in laboratory experiments, and for linuron reasonably well also in field experiments. In the field experiments the herbicides penetrated the top soil layer. In the subsoil the risk of further transport downward to the drainage system or ground water increased, especially for hexazinone. Linuron as well as the fungicides maneb and tolylfluanid suppressed the decomposition rate of hexazinone in laboratory experiments.     

竹大片刨花板对竹材生物学特性的适应性

以云南四种典型材用丛生竹（龙竹、甜龙竹、黄竹和油勒竹）宏观构造、组织结构、主要物理力学性质和化学组份等竹材主要生物学特性的研究分析结果为依据,提出了竹大片刨花板的结构、制板工艺和设备与原料竹材生物学特性之间应有的适应性关系。继而,通过实验室系列化试验和工厂试生产,确定了竹大片刨花板的应有性能和最佳工艺条件包括竹大片刨花的最佳质量指标及其最佳制备条件。     

浅议野生动物所有权

野生动物所有权是所有权的一种,它与其他所有权的区别在于客体的不同。文章阐述了野生动物的内涵,分析了野生动物的分类和野生动物与野生动物资源的区别。在明确野生动物含义的基础上,提出了野生动物所有权的概念,深入论述了野生动物所有权与野生动物资源所有权的差异和联系,并对野生动物所有权的主体、客体、内容进行了分析。     

Log sawing positioning optimization and log bucking of tropical hardwood species to increase the volume yield

The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber.     

Serological marking of <Emphasis Type="Italic">Pnigalio agraules</Emphasis> (Hymenoptera: Eulophidae) for field dispersal studies

The parasitoid wasp Pnigalio agraules (Wlk.) is a key natural enemy of the horsechestnut leafminer Cameraria ohridella Deschka and Dimić (Lepidoptera: Gracillariidae). As a basis for mark-release-recapture studies, aimed at investigating the dispersal of this parasitoid in the field, adults of P. agraules were marked using a vertebrate-specific immunoglobulin (IgG). The marker was later detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The IgG was either applied externally by spraying or internally by feeding an IgG-enriched diet. Different concentrations of the marker were used and the influence of abiotic (climatic conditions, time elapsed between marking and marker examination) and biotic factors (sex and age of the parasitoids) on the detection of the immunomarker was tested. External marking by spraying led to more homogeneous labelling than feeding the marker. Parasitoids labelled with 0.25 mg rabbit IgG per ten individuals contained enough immunomarker to be easily distinguished from unmarked ones. Neither the climatic conditions nor the sex or age of the insects had an influence on the detection of the marker. The IgG remained well detectable during the entire lifespan of the parasitoids, which was not negatively affected by the marking procedure. Serological marking can be used to investigate the dispersal behaviour of beneficial insects within mark-release-recapture studies.     

大兴安岭森林资源变化分析

阐述了人为破坏、过度采伐和自然森林火灾是引起大兴安岭森林资源变化的重要因子;通过对建国初到2002年大兴安岭森林资源在数量上和质量上的变化分析,得出了森林资源变化趋势。森林资源数量减少,且森林质量下降,大兴安岭的森林在经历着破碎化和年轻化的过程。     

四川湿地资源现状及其保护措施研究

湿地在我国分布比较广泛,在整个亚洲居于首位,但由于自然因素和人类的不当活动,我国的湿地面积锐减严重,且环境不断恶化。针对此种情况,本文详细论述了四川省湿地资源现状,并深入分析了造成此种情况的原因,最后给出了相应的治理对策。     

An evaluation of the Acacia albida-based agroforestry practices in the Hararghe highlands of Eastern Ethiopia

Growing Acacia albida as a permanent tree crop, on farmlands with cereals, vegetables and coffee underneath or in between, is an indigenous agroforestry system in the Hararghe highlands of Eastern Ethiopia. However, there is practically no systematic record or data on the merits and benefits of this practice.The paper presents the results of an investigation into the effects of the presence of A. albida on farmlands on the yield of maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench). Twenty seven plot pairs each consisting of one plot underneath the A. albida foliage cover and the other in the open, away from the tree-on farmers' fields, in a 40 km radius around the Alemaya College of Agriculture, were sampled and the yield components analyzed. A statistically significant increase in crops yields by 56% on average was found for the crops under the tree canopies compared to those away from the trees. This increase was caused by the improvement in 1000 grain weight and number of grains of plants under the tree, indicating that the trees enhanced the fertility status of the soil and improved its physical conditions in terms of crop growth.Additional benefits from the A. albida trees include supply of fuelwood and fodder. Quantitative estimates of these outputs as well as their monetary values are presented in the paper. However, in order to realize these benefits to a discernible extent, higher stand densities of the tree than at present are required.Based on an enquiry about the farmers attitude towards A. albida, the prospects for an extension of this promising agroforestry technique are discussed against the background of the state and trends of development of agriculture in the area. It is surmised that despite some shortcomings like the relatively slow and highly variable growth of A. albida and a conflict with the spreading cultivation of Ch'at (Catha edulis Forsk.), the prospects of extension of this technique are good. It is recommended that its propagation should be incorporated into the programmes of the extension agencies of the various governmental agencies concerned with land use.