环境生态学第十六章 组成成员和过程.ppt

1、P1 组成成员和过程,要 点,生态系统的 概念,1935年Tansley提出生态系统的概念，最初的定义包括一个定义的空间中所有的动物、植物和物理的相互作用。近代生态学家更倾向于从能（量）流、碳流或营养物流来考虑生态系统。,生态系统的构成,个体,水生生态系统,陆地生态系统,生态系统的概念,1、生物群落：,生活在一定自然区域内，相互有 直接或间接关系的各种生物的总体。,2、生态系统：,生态系统就是在一定的时间和空间内，生物和非生物的成分之间，通过不断的物质循环和能量流动以及信息传递而相互作用、相互依存的统一体，构成一个生态学的功能复合体。,陆地生态系统,森林生态系统,小树林,一颗树,地球生物圈,海

2、洋 淡水,草地 沙漠 苔原,最高级 高级 中级 小型 微生 态系统,生态系统=生物群落+无机环境,生态系统的共同特征,(一)、生态学上的主要结构和功能单位 (二)、生态系统内部具有自我调节的能力 (三)、能量流动、物质循环和信息传递是生态系统的三大功能。 (四)、生态系统是动态系统。,生态系统=生物群落+非生物环境,生态系统的组成,生产者+消费者+分解者+生境,阳光+大气+水+岩石等,气候因子 （光、温等及其他物理因子） 1非生物部分 无机物质 （H2O、N、P、K、Ca等矿质元素） 有机物质 （糖、蛋白质、脂类、腐殖质等） （1）生产者自养生物（把太阳能输入生态系统） 生态系统 草食动物（一

3、级消费者）(herbivores) 一级肉食动物（以食草动物为食， 统称二级消费者） 2生物部分 （2）消费者 肉食物动物 二级肉食动物（大型肉食动物） 称三 （能量传递） (comsumers) (carnivores) 级消 寄生者 三级肉食动物（顶极肉食动物） 费者 杂食动物 腐食性动物 （3）还原者（分解者）(reducers),生态系统的组成,The bodies of living organisms within a unit area constitute a standing crop of biomass: the mass of organisms per unit ar

4、ea of organisms per unit area of ground (or water), usually expressed in units of energy or dry organic matter (e.g. tons ha-1). The great majority of biomass in a terrestrial community I is the rate at which biomass is produced per unit area by plants, the primary producers. The total fixation of e

5、nergy by photosynthesis is referred to as gross primary productivty (GPP) of which a proportion (R) is lost form the community as respiration. The difference between GPP and R is known as net primary productivity (NPP) and represents the rate of production of new biomass that is available for consum

6、ption by heterotrophic organisms (bacteria, fungi and animals). The production of biomass by heterotrophs is called secondary production.,Ecosystem components,生态系统成分,单位面积中活有机体的身体构成了生物量（biomass）的现存量（standing crop）：单位地（或水）面积的有机体的质量，通常以能量或干有机质为单位（例如t/ha）陆地群落大部分生物是植被。群落初级生产率是初级生产者植物所生产的单位面积生物量的速率。通过光合作用

7、固定的总能量是总初级生产量（GPP），其中一部分从群落丢失于呼吸作用（R）。GPP与R之差称为净初级生产量（NPP），它代表了新生物量的产生速率，并可供异养生物（细菌、真菌和动物）消费之用。被异养生物生产的生物量叫做次级生产量。,The first law of thermodynamics states that energy can neither be created nor destroyed. The second law of thermodynamics states that every transformation results in a reduction of the

8、free energy of the system. Because energy transformation cannot be 100% efficient (from the second law), heterotrophs must have less energy,and must therefore be rater than the plants they feed on. The complexity of ecological interactions means that it is not possible to construct predictive mathem

9、atical models of living systems based on these laws of thermodynamics.,Ecosystems and the laws of thermodynamics,生态系统与 热力学定律,热力学第一定律说明，能量既不能被创造，也不能被破坏。热力学第二定律说明，每一次“转换都导致系统的自由能的减少”。因为能量转换不可能100%的有效，因此异养生物的能量较少，必然比它们所吃的植物更少。生态相互作用的复杂性意味着，以这些热力学定律为基础去构建用于预测的数学模型是不可能的。,辐射能,有机物质的合成过程，即生产者（绿色植物）吸收太阳能量形成初

10、级生产量。,热 能 化学能,热 能 机械能,活有机物质被各级消费者（动物）消费的过程。,死有机物质（动植物残体和排泄物）被腐生物分解的过程。,能量流动特点： 1 单向流动，不可逆。 2 “越流越细”，能量在流动过程中逐渐耗散。,生态系统中的能量流动,（1/10法则、10%定律）,“低效性”-逐级递减,“一山不存二虎”？,The proportion of net primary production that flows through trophic levels depends on transfer efficiencies in the way energy is used and p

11、assed from one step to the next. A knowledge of just three categories of transfer efficiency is all that is required to understand the pattern of energy flow. These are consumption efficiency (CE), assimilation efficiency (AE) and production efficiency (PE). Consumption efficiency is the percentage

12、of total productivity available at one trophic level (Pn-1) that is actually consumed (ingested) by a trophic compartment one level up (In). Assimilation efficiency is the percentage of food energy taken into the guts of consumers in a trophic compartment (In) which is assimilated across the gut wal

13、l (An) and becomes available for incorporation into growth or used to do work. Production efficiency is the percentage of assimilated energy (An) which is incorporated into new biomass (pn). The remainder is entirely lost to the community as respiratory heat.,Transfer efficiencies,转换效率,净初级生产力通过营养级流动

14、的比例，决定于能量从一级到下一级的利用、通过途中的转化效率。正是三类转换效率的全部知识，是预测能量流动格局的全部要求，那就是消费效率（CE）、同化效率（AE）和生产效率（PE）。消费效率是指一个营养级的有效总生产力（P n-1）中，后一营养级成员实际消费（被吃掉）部分（I n）所占的百分比。同化效率是指一个营养级的消费者吃入消化道的食物能量（In）中，被同化而穿过消化道壁、并成为参加生长或用于作功的有效能量（A n）所占的百分比。生产效率是指被同化的能量中（A n），加入到新生物量（P n）所占的百分比。剩留下来的完全以呼吸热量而损失于群落。,Related topics,Primary an

15、d secondary production The community, structure and (P2) stability (Q1) Food chains (P3) Community patterns, competition and predation (Q3),Energy flow through a community,Given that specified values can be obtained for not primary production and CE, AE and PE, it is possible to predict, using model

16、s, the pathway of energy flow at different trophic levels for different communities. From such modeling studies, which are supported by field data, the most significant finding is the overwhelming importance of the decomposer system. Overall, in a steady state community, losses through animal respir

17、ation balance NPP so that standing crop biomass remains the same.,通过群落的 能流,如果净初级生产量和CE、AE和PE是已知的值，那么运用模型预测不同群落各个营养级的能流途径是可能的。从这种有野外数据支持的模型研究得到了一个有意义的发现，即分解者系统是非常重要的。有普遍意义的是，在状态稳定的群落里，动物呼吸所丢失的被NPP所平衡，所以现存生物量保持一样的水平。,相关主题,初级和次级生产力（见P2） 群落、结构和稳定性（见Q1）食物链（见P3） 群落格局、竞争和捕食（见Q3）,Global net primary producti

18、vity is approximately 120109 tons fry weight per year on land, and 50109 tons per year in the sea. This productivity is very unevenly distributed across the Earth. The most productive systems are found amongst swamp and marshland, estuaries, reefs and cultivated land. Productivity decreases moving a

19、way from the equator, indication the importance of temperature and radiation.,Key Notes,Primary production,P2 PRIMARY AND SECONDARY PRODUCTION,P2 初级和次级生产力,要 点,初级生产力,全球陆地的净初级生产力大约为12010 9 t / a干物质，而海洋的大约为50 10 9 t / a干物质。这种生产力在地球上分布是很不均匀的。最富有生产力的系统出现在沼泽、湿地、河口湾、珊瑚礁和耕田。生产力随离赤道距离增大而降低，它表明温度与辐射的重要性。,四 生态

20、系统的能量动态和储存,基本名词解释 生产量(production)：一定时期内有机物质增加的总重量。 总生产量(gross production)：某一时期合成的有机物质总量. 净生产量(net production)：总生产量减去呼吸损失的部分. 初级生产量(primary production)：绿色植物的生产量. 次级生产量(seconddary production)：消费者的生产量.,生物量(biomass)：任一时间某一地方某一种群、营养级或某一生态系统有机物质的总重量。(kg/ha、g/m2、kj/m2) 现存量(standing crop)：单位面积上当时所测得的生物体的总重量

21、。 生产力(productivity)：指单位时间单位面积的生产量，即生产的速率。,红树林沼泽,湿地,河口湾,珊瑚礁,Community productivity can bi related to the standing crop that produces it by comparing the ratio of productivity (P) to standing crop biomass (B). The resulting P:B ratios (I.e kg produced year-1 kg-1 standing crop) average 0.042 for fores

22、ts, 0.29 for other terrestrial systems, and 17.0 for aquatic communities. An alternative way of looking at P:B ratios would be to define biomass in terms of weight of living tissue, which would reduce these large differences between communities. However, accurate measurement of the proportion of bio

23、mass alive is difficult.,Relationship of productivity to biomass,生产力对生物量的关系,通过生产力（P）与现存生物量（B）之比，可以把群落生产力与产生它的现存量联系起来。对于森林，所得到的P：B比率（即每年每公斤现存量所生产出的公斤数）平均为0.042，其他陆地系统是0.29，而水体群落是17.0。考虑P：B比率的另一种选择是以活组织的重量确定的生物量，它将缩小群落之间的这些大的区别。当然，精确测定活的生物量比例是很困难的事。,Secondary production is defined as the rate of produ

24、ction of new biomass by heterotrophic organisms. Heterotrophs are organisms, such as animals and fungi, with a requirement for energy-rich organic molecules. Secondary production by heterotrophs is inevitably dependent on primary productivity. Generally, in grazer systems, that part of the trophic s

25、tructure of a community which depends on the consumption of living plant biomass, secondary productivity is an order of magnitude less than primary production resulting in a pyramidal structure. However, there are exceptions to this.,Secondary production,次级生产力,次级生产力的定义是异养有机体的新生物量的生产速率。异养生物如动物、真菌，要求能

26、量丰富的有机分子。异养生物的次级生产力必然地依存于初级生产力。一般说来，在牧食者系统中，次级生产力是群落营养结构中，依存于消费活植物生物量的那一部分，在数量级少于植物生产力，从而形成了金字塔结构。然而也有例外。,次级生产量的一般生产过程,Related topics,Solar radiation and plants (F1) Components and processes (P1) Plants and consumers (G2) Food chains (P3),The relationship between matter and energy,Once energy is tra

27、nsformed into heat, it can no longer be used by living organisms to do work or to fuel the synthesis of biomass, the heat is lost to the atmosphere and can never be recycled. Life on Earth is possible because a fresh supply of solar energy is made available every day, In contrast, nutrients such as

28、carbon can be reused. Chemical nutrients, the building blocks if biomass, can be used again, and recycling is a critical feature. Unlike the energy in solar radiation, nutrients are not in unalterable supply of nutrients would become exhausted and life on Earth would cease.,相关主题,太阳辐射与植物（见F1） 组成成员和过程

29、（见P1）植物与消费者（见G2） 食物链（见P3）,物质与能量的关系,能量一旦转化为热，它就不再能被有机体用于作功或合成生物量的燃料。热损失到大气中，再也不能进入再循环。地球上生命所以能够存在，正是由于太阳辐射每天都提供着新鲜的可用能量。相反，像碳一样的营养物，就能被再利用。构成生物量基块的化学营养物可以被利用，以临界的特征在再循环着。与太阳辐射的能量不同，营养物的供应不是不会改变的。如果植物及其消费者没有被最后分解掉，营养物的供应将会耗尽，地球上的生命也将终止。,生态系统的能量流动是随着物质循环而进行的，二者互为因果、相辅相成，具有不可分割的联系。生态系统的各成分中，通过能量流动和物质循环而

30、紧密地联系在一起，形成一个统一的整体。,Autotrophic organisms assimilate inorganic resources into packages of organic molecules. There become the resources for heterotrophs which then become a resource for another consumer. At each link in this food chain we can recognize three pathways to the next trophic level: decom

31、position, parasitism and predation. Consumers may be generalists (polyphagous), taking a wide variety of prey species or may specialize on single species or a range of closely related species (monophagous).,Key Notes,Pathways of nutrient flow,P3 FOOD CHAINS,3 食物链,要 点,营养物流,自养生物同化无机资源，生成有机分子的组件，这些组件成为

32、异养生物的资源，后者又后为另一个消费者的资源。在这种食物链的每一个连接，我们能够辨别出通向下一个营养级的三条途径：分解、寄生和捕食。消费者可能是泛化种（多食性的），吃广范围的猎物种，或者是特化为吃一个或一组有密切关系的种（单食性的）。,“稻田生态系统”,化学元素 简单化合物,植食,肉食,初级 次级 三级 四级消费者,A characteristic of an ecosystem is the number and nature of the species that occupy its various trophic levels. The relationship between con

33、stituents of one trophic level and constituents of adjacent trophic levels may be described by a food chain. This is a chain of eating and being eaten that connects, for example, carnivorous animals to their ultimate plant food. Many food chains exist in any given ecosystem and van be combined into

34、food webs. Ecosystems vary considerably in the pattern of their energy-nutrient webs.,Interactions between trophic levels,营养级间的 相互作用,生态系统的一个特征是：占据其各个营养级的种数及种的性质。一个营养级的成员与邻近营养级的成员之间的相互关系可以用食物链来描述。食物链是连接吃与被吃的链，例如，食肉动物到它的最后的植物食物。任何生态系统都有许多食物链，并可以组成食物网。生态系统在能量-营养物网的模式上有很大的变化。,生物之间由于食物关系而形成的一种联系,食物链,第四营养

35、级,第三营养级,第二营养级,第一营养级,蛇,“螳螂捕蝉，黄雀在后” “大鱼吃小鱼，小鱼吃青虾，青虾吃泥巴（主要指浮游植物）” 这两句谚语是否构成食物链？ 请说明理由！,食物网：许多长短不一的食物链互相交织成复杂的网状关系,营养级和生态金字塔,一个营养级是指处于食物链某一环节上的所有生物种的总和。,四级消费者 三级消费者 二级消费者 一级消费者 生产者,营养级和生态金字塔,生态金字塔是指各个营养级之间的数量关系，这种数量关系可以用生物量单位、能量单位和个体数量单位表示，采用这些单位所构成的生态金字塔分别称为生物量金字塔、能量金字塔和数量金字塔。,p,1C,2C,3C,4C,p,1C,2C,3C,

36、4C,p,1C,2C,p,1C,2C,3C,3C,数量,能量,落叶林,草地,落叶林及草地数量和能量金字塔,单位：公斤,生物量金字塔,浮游动物,鱼,浮游植物,能量金字塔,请大家思考，有没有可能出现倒置的金字塔的情形？,Top-down or bottom-up?,It has been argued that the earth is green and vegetated because herbivore numbers are regulated by their predators (top-down control), whilst all other trophic levels are regulated by competition f