农业生态学国家精品课程课件（第三章）ppt课件

第三章 能量流动 Chapter 3 Energy flow,2019/5/11,1,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,2,一、能量转移 二、农业生态系统遵守能量流动的基本规律 三、食物是农业生态系统中的能量载体 四、农业生态系统的能源、能流途径和能效 五、农业生态系统的能流调控,主要内容,2019/5/11,国家级精品资源共享课,3,（一）能量转移 植物利用太阳能，通过光合作用生产食物能，食物能通过食物链和食物网，从一个营养级传递到另一个营养级。,一、能量转移,食草动物,食肉动物,2019/5/11,4,国家级精品资源共享课,The relationship between matter and energy,Once energy is transformed 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 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. If plants, and their consumers were not eventually decomposed, the supply of nutrients would become exhausted and life on Earth would cease.,2019/5/11,5,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,6,1.流生态系统中能量和物质不断地被吸收、贮存和转移的运动状态。能量的转移能量流。物质的转化物质流。流量要多，流速要快 增加流量的方法：提高能量转化效率、减少消耗 增加流速的方法：缩短周转周期、提高周转速率,（二）流、库、环的概念及应用,2019/5/11,国家级精品资源共享课,9,（一）热力学第一定律,二、农业生态系统遵守能量流动的基本规律,（二）热力学第二定律,1.能量传递有一定的方向，是不可逆的。 2.能量转化过程中存在着衰变现象，必然有能量的耗散。 3.为了判断能量流动的方向和限度，用自由能和熵来描述。,2019/5/11,国家级精品资源共享课,10,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 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 rarer than the plants they feed on. The complexity of ecological interactions means that it is not possible to construct predictive mathematical models of living systems based on these laws of thermodynamics.,Ecosystems and the laws of thermodynamics,2019/5/11,国家级精品资源共享课,11,（三）耗散结构理论, 普里高津耗散结构理论 Prigogines dissipation structure theory 指开放系统在远离平衡态的非平衡态下，系统可能出现的一种稳定的有序结构。 表明：一个远离平衡态的开放系统，通过与外界环境进行物质、能量的不断交换，就能克服混乱状态，维持稳定状态并且还有可能不断提高系统的有序性，使系统的商减少。,2019/5/11,国家级精品资源共享课,12,1.根据热力学第一定律，可以对农业生态系统的能量流进行定量研究。 2.在农业生态系统能量流中，只有少部分转化成有机形态的化学潜能储存起来，大部分转化成热能而耗散。 3.能量流的流动方向是不可逆的，能量只能称为转化或转移，而不能是循环。 4.为了维持农业生态系统的稳定，应不断的向系统输入能量，减少熵。,(四)热力学定律在农业生态系统中的应用,2019/5/11,国家级精品资源共享课,13,（一）食物链 1.定义：生态系统中，来源于植物的食物能通过一系列吃与被吃的关系，把生物紧密的联系起来，形成以食物营养为中心的链索关系即食物链。 典型的食物链：植物食草动物一级食肉动物二级食肉动物顶级食肉动物,三、食物是农业生态系统的能量载体,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: decomposition, 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).,Pathways of nutrient flow,2019/5/11,14,国家级精品资源共享课,食物链,2019/5/11,15,国家级精品资源共享课,A characteristic of an ecosystem is the number and nature of the species that occupy its various trophic levels. The relationship between constituents 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 can be combined into food webs. Ecosystems vary considerably in the pattern of their energy-nutrient webs.,Interactions between trophic levels,2019/5/11,16,国家级精品资源共享课,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 for resources (bottom-up control). This simple model is attractive but of doubtful value. Herbivore species are highly constrained in the range of plant tissue they can eat, due to plant defences, and hence may be limited by competition even if the world is green. Further, at a gross level, plants are not energy-limited but space limited, so any space cleared by herbivory opens opportunities for more plants.,2019/5/11,17,国家级精品资源共享课,一个食物链的例子“螳螂捕蝉，黄雀在后”,螳螂捕蝉，黄雀在后！哈！哈！,2019/5/11,18,国家级精品资源共享课,食物链的基本类型（四种）,（1）捕食食物链，又称为活食或草食食物链 海洋中：浮游植物浮游动物虾鱼 草原上：草羚羊老虎 农田中：水稻蝗虫青蛙 农业生产中：作物秸秆牛人 （2）腐生食物链，又称碎屑或残渣食物链 农业上用秸秆、粪便生产沼气 棉籽壳、稻草培育蘑菇,2019/5/11,19,国家级精品资源共享课,（3）寄生食物链 植物型：大豆菟丝子 动物型：哺乳动物跳蚤原生动物细菌病毒；马蛔虫 （4）混合食物链 稻草牛（牛粪）蚯蚓鸡（鸡粪）猪（猪粪）鱼；稻螟赤眼蜂；菜（温棚）鸡（鸡粪）沼气（沼渣）肥田,2.营养级：生物在食物链上所处的位置，即食物链上每一个环节称为营养级。,2019/5/11,20,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,21,海洋生态系统的食物链,The Trophic Pyramid: A Model of Consumption,2019/5/11,22,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,23,海洋与陆地生态系统的食物链,2019/5/11,国家级精品资源共享课,24,（1）同一食物链中常含有食性和生活习性极不相同的生物。 （2）同一生态系统中可能有多条食物链，各种食物链相互联系，协同发挥作用。 （3）自然生态系统中，营养级的数目是有限的。 （4）不同生态系统中，各类食物链的比重不同。 森林生态系统：腐生食物链占生产有机物的90% 草原生态系统：腐生食物链占生产有机物的70% 农田生态系统：腐生食物链占生产有机物的20%30%,3.食物链的基本特征,2019/5/11,国家级精品资源共享课,25,1.食物网和营养结构的概念 食物网：生态系统中，一种生物常常以多种生物为食，同一生物又常常被多种生物取食，于是食物链交错起来，多条食物链相互连接、形成的网状结构。 营养结构：以营养为纽带，把生物与环境、生物与生物，紧密连接起来的结构。,（二）食物网和生态系统的营养结构,Food Webs Illustrate Complex Trophic Relationships,2019/5/11,26,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,27,生态系统抵抗外界干扰、自动修复的能力称为生态系统的稳定性。影响稳定性的因素有很多，如生物的适应性、外界干扰的程度、营养结构等。 营养结构复杂、食物网复杂的生态系统，稳定性强,2.营养结构与生态系统的稳定性,2019/5/11,国家级精品资源共享课,28,（一）农业生态系统的能源 1.太阳能是生态系统的主要能源 2.农业生态系统的辅助能 辅助能的类型：自然辅助能、人工辅助能：生物辅助能（有机能）、工业辅助能（无机能） 辅助能的性质：不能转化成生物能，对生物能的合成、转化起辅助作用 辅助能的作用：促进转化、减少消耗、改善环境,四、农业生态系统的能源、能流途径和能效,2019/5/11,国家级精品资源共享课,29,（二）农业生态系统的能流途径,生态系统中能量流动是指能量由非生物环境经生物有机体，再到外界环境所进行的一系列传递过程。在农业生态系统中，能量流动的一般途径包括以下几个方面： 1.太阳辐射的能量进入生态系统 2.以植物有机体储存的能量，沿食物链流动转化 3.生态系统中能量的外界输入及输出,生态系统中的能量流动,输入生态系统中的能量（太阳能）总是和生物有机体贮存、转换的能量和释放的热量相等。 以热的形式散失的能量不能再回到生态系统参与流动和被利用,2019/5/11,30,国家级精品资源共享课,Connections: Food Chains and Energy Flow in Ecosystems,Ecological efficiency=10% Loss?,2019/5/11,31,国家级精品资源共享课,Primary producers,100 J,1,000,000 J of sunlight,10 J,1,000 J,10,000 J,Primary consumers,Secondary consumers,Tertiary consumers,2019/5/11,32,国家级精品资源共享课,The dynamics of energy through ecosystems have important implications for the human population.,2019/5/11,33,国家级精品资源共享课,Energy flow through a community,Given that specified values can be obtained for net primary production and CE, AE and PE, it is possible to predict, using models, 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 respiration balance NPP so that standing crop biomass remains the same.,2019/5/11,34,国家级精品资源共享课,太阳辐射能,24%,52%,云层吸收 10 %,浮尘 15%,反射 25%,臭氧层、 水蒸气等 9%,24%,地球表面,47%,反射 4%,散射 6%,散射 17%,散射 损失 9%,2019/5/11,35,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,36,一个稳定生态系统的能量流,2019/5/11,国家级精品资源共享课,37,2019/5/11,国家级精品资源共享课,38,Ecosystem Energy Flow,生态系统的能流,能流特征 逐级减少 单方向性 能流路径,2019/5/11,39,国家级精品资源共享课,Assimilatory:同化的 Dissimilatory：异化的,2019/5/11,40,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,41,1.能量流动过程中损耗的必然性 （1）由于不可食或不得食 （2）消费者密度低或食物选择限制 （3）利用后未被同化 （4）同化后呼吸消耗掉 （5）变为生产量又被减少 营养级能量传递效率约平均为10%。,（三）农业生态系统的能效和生态金字塔规律,2019/5/11,国家级精品资源共享课,42,2.能量传递效率（生态效率）：通常指食物链各环节上能量的各种转化效率。 肉猪35%、奶牛 20%、蛋鸡15%、肉兔1318%、肉羊11%、肉牛58%。,2019/5/11,国家级精品资源共享课,43,新陈代谢、生长和运动是生命的基本功能 物理运动化学运动生命运动,2019/5/11,国家级精品资源共享课,44,3.生态金字塔规律,生态金字塔是生态学研究中用以反映食物链各营养级之间生物个体数量、生物量和能量比例关系的一个图解模型。 类型 数量金字塔 树木昆虫鸟类（畸形金字塔） 生物量金字塔 浮游植物浮游动物底栖动物（倒置金字塔） 能量金字塔,能量金字塔,2019/5/11,45,国家级精品资源共享课,2019/5/11,国家级精品资源共享课,46,Biomass and productivi