多露石石漠化区岩面流对岩-土界面土壤的冲蚀效应

岩面流在基岩出露的喀斯特石漠化区普遍存在,其容易受岩面形状影响以汇聚或分散的方式对岩—土界面处土壤进行冲刷侵蚀,这是喀斯特石漠化区土壤侵蚀/漏失发生的重要物理过程。为分析不同岩面形状下岩面流对岩—土界面土壤颗粒分布的影响,揭示岩面流对岩—土界面土壤的冲蚀效应,选择具有典型石漠化特征的休耕地(1年岩面流冲刷作用),在其中选取3种典型岩面形状(平直型、外凸型和内凹型岩面)为研究对象,采用激光粒度仪分析法,分析距岩—土界面不同水平距离(0～2,2～4,4～6,6～8,8～10,20 cm)及不同土层(0—10,10—20 cm)处土壤的颗粒分布特征。结果表明：(1)不同岩面形状下岩面流对岩—土界面处土壤的冲蚀影响依次为内凹型>平直型>外凸型;内凹型岩—土界面处土壤中黏粒含量最低,外凸型岩—土界面处土壤中黏粒含量最高;(2)岩面流对岩—土界面土壤冲蚀作用主要集中在距岩—土界面水平距离0～2 cm范围内,在其范围内内凹型岩—土界面土壤的砂粒含量均显著高于外凸型和平直型,而在距岩—土界面其他水平距离处土壤颗粒分布情况无显著性差异;(3)在岩面流影响下岩—土界面土壤颗粒分形维数均值排序依...     

The effect of veld condition on the quality of diet selected by cattle grazing the Natal Sour Sandveld

The quality of diet selected by steers fistulated at the oesophagous was related to veld condition in a simulated rotational grazing system on the Natal Sour Sandveld. Six camps, ranging in veld condition score from 8,5 to 53%, were grazed simultaneously for a two‐week period in spring, summer, autumn and winter. Fistula samples were collected on the first, middle and last day of a period of occupation in a camp. Samples were analysed in terms of crude protein (CP), in vitro digestibility (IVD) and plant‐part (% leaf, % stem and % dead material) composition. Dietary quality in terms of CP, IVD and plant‐part composition was not related to veld condition but was dependent largely (P≤0,01) upon season and to a lesser extent upon period of occupation in a camp. It was concluded that in sourveld areas, where dietary quality may be limiting, the veld condition score may be a poor index of potential animal production.     

Vegetation gradients around cattleposts in the eastern mountains of Lesotho

The grasslands of the mountains in eastern Lesotho support large numbers of sheep, angora goats and other livestock during the summer, during which they are corralled nightly by herders at cattleposts. Few studies, however, have quantified the impact of grazing on the composition and structure of the mountain grasslands. Gradients of grazing and trampling intensity related to distance from 23 cattleposts in the subalpine and alpine belts (2 650–3 175 m above sea level) were examined to describe the long-term effects of livestock on unpalatable dwarf shrubs, bare area and plant species composition. The potential for shrub invasion and bare areas (low herbaceous cover) to develop was highest near cattleposts. Species composition also changed significantly along the grazing gradient, accompanied by a shift in dominants from grazing-sensitive to grazing-resistant grasses and shrubs. Species either decreased or increased monotonically along the grazing gradient or had an intermediate, unimodal response. The relative positions of species’ centroids along the grazing gradient were used to quantify their grazing sensitivity on a scale from 10 (most sensitive) to 0 (most resistant), which confirmed and contradicted previous classifications of their grazing responses. Basic ecological research on this important mountain grazing and catchment system is recommended.     

Section A. Physiology and Behaviour

An effective live-trap was designed for Cryptomys hottentotus (Bathyergidae) arid Amblysomus hottentotus (Chrysochloridae). Factors involved in the design and adaptability of this trap for use in various field conditions and live capture of other fossorial mammals are discussed.     

狼毒及瑞香狼毒的研究进展

大戟科狼毒含有挥发油成分、萜类、植物甾醇类、蒽醌、鞣质类、苯乙酮、杀虫成分。月腺大戟还分离出了黄酮类化合物;而瑞香狼毒含有木脂素、黄酮类化合物、二萜类化合物、香豆素类化合物、三萜类化合物、甾醇类以及其他成分。大戟科狼毒与瑞香狼毒的生物活性都有抗癌或抗肿瘤、抗茵、抗病毒、抗惊厥、杀虫作用,但二者的作用方式却不同,大戟科狼毒还独有抗白血病作用,而瑞香狼毒独有治疗和预防免疫缺陷的作用。关于狼毒的记载与研究的历史较早,但对于瑞香狼毒与大戟科植物狼毒大戟和月腺大戟的收载比较混乱,因此,对瑞香狼毒与大戟科狼毒在植物形态、生长分布、化学成分研究以及生物活性研究上进行了对比。     

帽儿山林场集水区森林景观格局特征的研究

本文以黑龙江省帽儿山林场为研究区域,采用ArcGISIO．0空间分析模块划分该地区集水区的森林,并通过Frag＋stats3．3对帽儿山林场集水区从斑块水平和斑块类型水平上景观格局进行分析。其中,景观格局指标包括：斑块面积、面积比、斑块数、斑块密度、形状指数、分维度等。研究结果表明：软阔混交林是帽儿山林场集水区主要的森林景观类型,是其森林资源的重要组成成分,其次是硬阔混交林,柞树林,白桦林等,景观资源丰富。该地区景观特征的研究为帽儿山集水区森林景观规划、森林景观生态系统优化提供了理论参考,对改善帽儿山集水区地区森林结构、更好地实现森林空间布局的优化配置和发挥森林的生态功能等方面具有重要意义。     

Species Interactions in the Dynamics of Even- and Uneven-Aged Boreal Forests

Many boreal tree stands are neither clearly even-aged nor clearly uneven-aged. The stands may undergo a series of stages, during which an even-aged stand is transformed into two-storied mixed stand, and finally to multistoried or uneven-aged stand structure. The species composition often changes during the succession of stand stages. This study developed models for stand dynamics that can be used in different stand structures and species compositions. The model set consists of species-specific individual-tree diameter increment and survival models, and models for ingrowth. Separate models were developed for Scots pine, Norway spruce, and hardwood species. The models were used in a growth simulator, to give illustrative examples on species influences and stand dynamics. Methods to simulate residual variation around diameter increment and ingrowth models are also presented. The results suggest that mixed stands are more productive than one-species stands. Spruce in particular benefits from an admixture of other species. Mixed species improve diameter increment, decrease mortality, and increase ingrowth. Pine is a more beneficial admixture than birch. Simulations showed that uneven-aged management of spruce forests is sustainable and productive, and even-aged conifer stands growing on medium sites can be converted into uneven-aged mixed stands by a series of strong high thinnings.     

The Relationship Between the Chemical Properties of Native Woody Species and the Soil,in a Secondary Forest of the Eastern Chaco (Argentina)

Abstract

The horizontal distribution of trees within forests is due in part to the composition of the substrate, but there are also effects of the trees on the properties of the soil. This work focused on the relationship between the chemical composition of the foliar tissues of four species of the most abundant deciduous trees found in the “quebrachal” (xerophitic forest), and the chemical properties of the soil under their crowns. The species were two trees: Schinopsis balansae Engl. and Acacia praecox Gris. and two bushes, Maytenus vitis-idaea Gris. and Achatocarpus praecox Gris. The chemical variables that were analysed were: C/N, N, Ca, Mg, K and P. The most important association between the foliar tissues and the soil was found for P, under the crown of S. balansae. These results would reassure the idea that the most important woody species within the “quebrachal” would be modifying the conditions of the substrate.     

环境美学视野下城市滨水公园景观优化设计研究——以泉州市西湖公园为例

文章从环境美学视野对城市公园景观优化设计进行研究,从环境美学的内容、应用价值、意义,以及城市公园景观优化设计中应用环境美学的原则入手,以泉州市西湖公园为例,介绍其景观优化设计方式,包括改善西湖公园湖滨游步道的林荫绿化情况,增建亲水空间,优化座椅、休闲亭和餐饮设施,改善水景别墅前绿化景观,提升公园整体植物景观层次感,规划西湖水生植物景观。从而总结出滨水公园景观优化设计的策略主要为：设计湖滨亲水设施、营造水上景观、配置滨水植物景观、设置沿岸小型水景。     

重庆园博会韶关展园设计

韶关展园主要由风采楼、丹霞画卷、马坝智人景点构成,中间水系按照韶关“三江六岸”地形作为水体走向。展园通过展示韶关的地标和重要旅游景点,表现韶关的风采。