1. ENERGY FLOW INECOSYSTEM

2. An Ecological System? In the discipline of ecology, the wordEcosystem is an abbreviation of the term, Sir Arthur Tansley (1871-1955)ecological system the basic unit in ecology. It firstappeared in a 1935 publication by the British ecologist ArthurTansley (Tansley, 1935). However, the term had been coinedalready in 1930 by Tansleys colleague Roy Clapham, who wasasked if he could think of a suitable word to denote the physicaland biological components of an environment considered inrelation to each other as a unit. Tansley, A., 1935, The use of vegetational concepts and terms. Ecology, v. 16, p. 284-307. 3. An Ecological System? Components of an Ecosystem:Sir Arthur Tansley (1871-1955) Abiotic (non-living) and Biotic Components Physical Components Species Water Populations NutrientsCommunities TopographyWeatherCompetition and Predation Disturbances 4. What Keeps Us and Other Organisms Alive? One-way flow of high-quality energy from the sun(returned as low quality heat) Cycling of matter or nutrients through parts of thebiosphere (closed system applies; law of conservationof matter; time frame of seconds to centuries) Gravity (maintains atmosphere, enables movement &cycling of air, water, nutrients) 5. Energy and the Laws ofThermodynamics20.1 The Laws of Thermodynamics Govern Energy Flow. Energy exists in many forms, such as heat, light, chemicalenergy, and electrical energy. Energy is the ability to bringabout change or to do work. Thermodynamics is the studyof energy. Kinetic energyEntropy Entropy Potentialenergy 6. Energy and the Laws of ThermodynamicsThe 1st Law of Thermodynamics:Energy can be changed from one form toanother, but it cannot be created ordestroyed. The total amount of energyand matter in the Universe remainsconstant, merely changing from one formto another. Isaac Newton (1643-1727) 7. Energy and the Laws ofThermodynamicsThe 2nd Law ofThermodynamics: "in all energyexchanges, if no energy enters or leaves thesystem, the potential energy of the state willalways be less than that of the initial state." Inenergy transfer, some energy will dissipateas heat. The flow of energy maintainsIsaac Newton (1643-1727)order of life. 8. Second Law of Thermodynamics - Scientists have studied many ecosystems and have concludedthat this energy loss is a constant pattern. In fact, scientists havecalculated that the percentage (%) of usable energy transferredfrom one organism to another is 10%. !! - That means that 90% of energy is lost as heat!!! So. if producers captured 10,000 calories from the sun, thenonly bout 1,000 calories will be available to support primaryconsumers (herbivores), and only about 100 calories to supportsecondary consumers (carnivores or omnivores). 9. 10% LAW.. !! In the Arctic, Eskimos hunt whales for food.Whales eat tons and tons of microscopicplankton. This plankton in turn eats microscopicalgae. It requires 1,000 units of energy (calories)of algae to produce 100 calories of planktonwhich is what a whale uses to produce 10calories of blubber (fat) to its body. Finallythese 10 calories of whale blubber containsenough energy to give the Eskimo one calorie ofenergy. 10. Trophic Levels Producers autotrophs-Photosynthesis Consumers heterotrophs-Primary-Secondary-Third-level Omnivores Detritus feeders / Decomposers 11. Trophic Levels Trophic Level = Feeding Level20 energy10 consumer energyProducers energy- Just like a skyscraperhas floors, or levels, anenergy Pyramid hasdistinct levels, calledTROPHIC LEVELS. 12. 4th Tr. Level 1 calorie eskimos3rd Trophic Level10 calories whales2nd Trophic Level 100 caloriesplankton 1st Trophic Level1000 calories algaeA healthy ecosystem will always havethe most energy available in the first trophiclevel. 13. Ecosystem Energetics- Energy Decreases in Each Successive Trophic Level. 14. Ecological pyramids The standing crop, productivity, number of organisms, etc. of anecosystem can be conveniently depicted using pyramids, wherethe size of each compartment represents the amount of the itemin each trophic level of a food chain.carnivoresherbivoresproducers Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem. 15. Pyramid of energy A pyramid of energy depicts the energy flow, orproductivity, of each trophic level. Due to the Laws of Thermodynamics, each higher levelmust be smaller than lower levels, due to loss of someenergy as heat (via respiration) within each level.carnivoresherbivoresproducers 16. Pyramids of Energy Suggests: The number of trophic levels are limited. At eachtrophic level, there is a dramatic reduction in energy. Eating at lower trophic levels means moreresources available. Movement up the pyramid explains the problemsof Biological Magnification (DDT, PCBs, etc.) 17. Food Chains andFood WebsHow energy moves in an ecosystem OR who eats who!? ;) 18. Food Chain: A food chain shows one path ofhow energy moves through an ecosystem Food Web: A food web shows many paths ofhow energy moves through an ecosystem. Afood web is made up of many different foodchains. 19. FOOD CHAIN 20. FOODWEB 21. Primary productivity Primary productivity is the rate of energycapture by producers.= the amount of newbiomass of producers, per unit time and space 22. Gross primary production (GPP)= total amount of energy captured Net primary production (NPP)= GPP - respiration Net primary production is thus the amount of energystored by the producers and potentially available toconsumers and decomposers. 23. Secondary productivity is the rate of productionof new biomass by consumers, i.e., the rate atwhich consumers convert organic material intonew biomass of consumers. 24. CONCLUSION Energy flow follows the second law ofthermodynamics Biomass decreases with increasing trophic level Ecological efficiency typically 10% 25. CREDITS:-PARTH - PRAFFUL-SUMIT -SHUHUL-VERNIKA - KOMAL-LAKSHYA- PRANSHU-RISHABH-ROHAN