浙江 林学 英语终极版.docx

1、浙江 林学 英语终极版SoilSoil as a general term usually denotes the unconsolidated, thin, variable layer of mineral and organic material, usually biologically active, which covers most of the earths land surface. Dictionaries often describe soil as the loose surface material in which plants grow. A soil is bo

2、th an ecosystem in itself and part of a larger ecosystem. In all terrestrial ecosystems, soils support organisms from microbes to forest trees and humans, and they support processes from water storage to waste decomposition. Soils are fundamental to the terrestrial ecosystems that they support, and

3、often influence aquatic ecosystems nearby or downstream. Soils are part of urban ecosystems, rural ones, highly managed and undisturbed ones. In these contexts, “a soil ” means a particular three-dimensional example of the larger body of material we call soil, separately defined for purposes of char

4、acterization, study, and interpretation; it is part of the landscape in which it naturally exists; and it has one or more characteristic layers with specific properties such as color, mineral and organic content, hardness, and thickness. If we dig it up, bulldoze it into a pile, or otherwise disturb

5、 it, “a soil” becomes just “soil” or “soil material”. “A soil” must be large enough to contain all the physical, chemical, biological, and morphological properties necessary to describe it and distinguish it from other soils. Such a volume, with a surface area of 1 square meter (1 m) and depth of 1.

6、5 m, is called a pedon. A soil develops from some starting material such as consolidated rock or unconsolidated material deposited by wind or water. The starting material is the parent material for a soil . A soil that originates from consolidated rock or unconsolidated material inherits the mineral

7、 types found there. In addition, over time, the original minerals are dissolved and new minerals form and accumulate in the soil. This process of dissolution and reformation of new minerals is part of the process of weathering. Soil formation begins after unconsolidated parent material is deposited

8、on a stable landscape or after bedrock has been exposed at the earths surface1. The rate of soil formation depends on the climate, especially the annual amount of precipitation and the average annual temperature. It also depends on the kind and amount of vegetation and the numbers, kinds, and activi

9、ty of the other organisms that live on and in the parent material. The organisms that colonize the parent material help to convert it to soil. Two other factors affect the rate of soil formation and the kind of soil that is created. These are topography and time. Topography, the slope of the land fr

10、om the horizontal and the compass direction the slope faces, affects the amount of precipitation that enters the parent material or soil and the temperature of the soil. These influence the kinds and numbers of organisms that live on and in the soil. All of the processes take time. Time zero is the

11、time at which a soil begins to form from parent material. Parent material, climate, vegetation, topography, and time are the factors of soil formation. A soil is a three-phase system: solid, liquid, and gas in intimate contact. Soil has two kinds of solid components: minerals derived from weathering

12、 rocks, and organic materials derived from plants and microorganisms. Soil may contain both unweathered minerals residual from the rock and the minerals that weathering produces. The principal weathering products are the abundant clay minerals that occur as small particles that cohere to one another

13、 and adhere, to other particles.Living in the soil are organisms of many kinds: plants, fungi, filamentous and single-celled bacteria and algae, and small animals from protozoa to worms, insects, and mammals. During the decay of plant tissue, large complex molecules form that remain in the soil as r

14、esistant by-products. These organic colloids are humus. It is produced from plant material by microbes operating under the influence of the soils special environment. Humus is important because it has properties of water retention, nutrient retention. Most soils consist of mineral particles of diffe

15、rent sizes: large particles called gravel, smaller ones sand, still smaller ones silt, and submicroscopic clay. The proportions of each size fraction combine to determine the soils texture, be it coarse (sandy), intermediate (loamy), or fine (clayey). Soil texture refers to particle sizes, and soil

16、structure refers to particle arrangements. In most soils, individual particles are bound together into structural units or aggregates. The most important binding agents are clay and humus. A structureless (nonaggregated) soil may be either an incoherent heap of particles in which no particles are st

17、uck together or a single compacted mass in which all the particles are stuck together. Good structure is common in uncultivated soils such as forest and grassland soils but is often lacking in cultivated soils. The solid mineral particles and organic coatings are the soils skeleton. The pores betwee

18、n the particles control the soils ventilation, water intake, water storage, and drainage. The size and shapes of the pores and the total pore space are important. Small pores, for instance, hold water well, but large interconnected pores are needed for water and air to move freely into and out of th

19、e soil. The gas phase, the soil air, is the channel for the movement (diffusion) of oxygen and other gases. It is the soils connection with earths atmosphere. The liquid phase, the soil water or soil solution, is the solvent in which many reactions occur, and it supplies water and dissolved nutrient

20、s to plants and microorganisms. Even in soil that seem dry to the touch, a water film covers the solid surface and fills the smallest pores. If the soil gets wetter, the films thicken and the larger pores fill. When even the largest pores are filled with water, the soil is said to be waterlogged or

21、saturated, a state in which water and dissolved substances move freely but gases move so slowly that oxygen normally becomes deficient. 土壤土壤通常是指覆盖在地球陆地表面的具有生物活性的疏松、易变的矿物和有机表层。词典通常把土壤定义为植物在其中生长的疏松表层。土壤本身是一个生态系统，也是更大的生态系统的组成部分。在所有的陆地生态系统中，土壤支持微生物、森林树木和人类，也支持从水的储藏到废物的分解。土壤是其所支持的陆地生态系统的基础，常常会影响附近和下游的水生态

22、系统。土壤是城市生态系统、农村生态系统、集约经营生态系统和未受干扰的生态系统的组成部分。本文中的“土样”是指具有特殊的三维结构，被我们称之为土壤的比较大的物质个体的样品，这是为了描述、研究和解释起见分开作的一个定义。土壤是自然存在的陆地生态系统的一部分，也具有一个或几个典型的层次，每个层次都有诸如颜色、矿物质和有机质含量、硬度和厚度等特殊性质。如果我们挖开土壤，把土壤推成土堆或用别的方式扰动它,“土样”刚好就成了“土壤”或“土壤物质”。“土样”必须大到足以含有对它进行描述和与其他土壤区别的所有物理、化学、生物和形态特征。我们称面积1m2、深度1.5m的土壤为单个土体。 土壤起源于一些起始的物质

23、，如岩石和由风、水作用的疏松沉积物。这一起始的物质就是土壤母质。起源于岩石或疏松沉积物的土壤与原地的矿物类型一致，另外随着时间的推移，原生矿物质会被分解，合成新的矿物质并在土壤中积累。这种矿物质的分解和新矿物质的合成过程是风化的一部分。当疏松母质沉积于稳定的地形上或母岩裸露于地表以后，土壤形成过程就开始了。土壤形成的速度取决于气候条件，特别是年降水量和年平均温度；它也取决于植被的种类和数量，以及生活在母质上和母质中的其他生物的数量、种类和活性。定植于母质中的生物促进母质向土壤转化。还有两种因素影响土壤的形成速度和形成土壤的类型，即地形和时间。地形即地面的坡度和坡向，影响进入母质或土壤中的降水量

24、和土壤的温度，这些又影响到土壤中生物的种类和数量。所有这些过程都需要时间。土壤形成初始时间是土壤从母质开始形成的时间。母质、气候、植被、地形和时间是土壤形成的五大因素。土壤是一个三相系统：固体、液体和气体。土壤固体包括两个部分：来源于风化中岩石的矿物质和来源于植物、微生物的有机质。土壤可含有岩石中的没有风化的矿物质残留物,也可含有风化产生的矿物质。主要的风化产物是丰富的黏土矿物，它们作为土壤中的小颗粒，彼此黏结并黏附到其他颗粒上。土壤中的生物有许多种：植物、真菌、丝状单细胞细菌、藻类，包括原生动物到蠕虫、昆虫和哺乳动物的小动物。在植物残体的分解过程中，复杂的大分子物质作为难分解的副产物留在土壤

25、中。这些有机胶态物质就是土壤腐殖质。腐殖质是在土壤的特殊环境影响下微生物作用于植物材料而产生。土壤腐殖质非常重要，因为它能保持土壤的水分和养分。多数土壤由大小不同的颗粒组成，大的颗粒称为石砾，小一点的称为砂粒，还小的称为泥沙，更小的称黏粒。各种颗粒组合的比例决定土壤的质地，即粗（砂质）、中(粉质)和细（黏质）。土壤质地指颗粒的大小，土壤结构指颗粒的排列组合。在大多数土壤中，各个单粒黏结成为结构单位或团聚体，最重要的黏结因子是黏粒和腐殖质。无结构（非团聚性）的土壤可以是一堆互不黏结的单粒，也可以是单粒黏结在一起成一个致密的团块。没有供作的土壤如森林土壤和草地土壤通常具有良好的结构，但耕作土壤常缺

26、乏良好的结构。土壤矿物质和土壤有机质是土壤的骨架。颗粒间的孔隙控制土壤的通气，水分的进入、储藏和排出0孔暸的大小和形状及总孔隙度很重要，例如，小孔隙保水性好，但互相连接的大孔蒙对于土壤中水分和空气的自由进出是必需的。土壤气相，即土壤中的空气，它是氧气和其它气体运动（扩散）的通道。它是土壤和大气取系的方式。土壤液相，即土壤中水分或土壤溶液，它是各种土壤反应发生的地方，它供应植物和微生物需要的水分和养分。即使在感觉干燥的土壤中，水膜也覆盖在土粒周围和充满最小的孔隙。当最大的孔隙几乎也充满水时，土壤水分就饱和了，这时水分和溶解物质寻以自由移动，但空气运动变慢，易缺乏氧气。Lesson13 The C

27、haracters of EcosystemWe can view a forest as a system that absorbs, transforms, and stores energy. In this view, physical, chemical, and biological structures and processes are inseparable. When we look at a forest(or stream or coral reef) in this way, we view it as an ecosystem.In fact, the ecosys

28、tem is a biological community plus all of the abiotic factors influencing that community.The biologic and abiological components both are indispensable.Though the organisms may claim our primary interest ,we cannot separate them from their special environment, with which they form one physical syste

29、m .It is the eco systems so formed which, from the point of view of the ecologist, are the basic units of nature on the face the earth.Before 1935, there are a great many of conceptions to describe that biological community, including biocoenose, microcosm, naturecomplex,holocoen, biosystem and so o

30、n. The term ecosystem and its definition were first proposed in 1935 by the British ecologist Arthur Tansley.An ecosystem is a biological community in which all the biological(including human bings)and abiological(physical and chemic ingredients in the environment) components interact each other by

31、the flows of energy and nutrient cycling.According to all the conceptions of ecosystem, four characters can be generalized as follow: The Character of StructureEcosystem is composed by biological components and abiological environment. Biological component can be concluded into 3 portions. 1 Produce

32、r, mainly including plants, which are the fixation of energy by autotrophs in a ecosystem. 2 Consumer, including animals, which live on the plants or other kinds of animals. 3 Decomposer, including bacterium and epiphytes, which live on the corpses of other plants and animals. They can decompose com

33、plex organisms into simple mineral which can be absorbed by producers. Abiological environment indicates light, heat, air, water, soil, rock, dead organism etc. , which life-form depend on to survive. Observing the nutritional structure of abiological environment in a land ecosystem, it can be divided into two layers.