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Dr.TomHunt,United States,Teacher
Published Date:23-07-2017
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ECOSYSTEM  The term ecosystem is coined from a Greek word meaning study of home.  It is the basic functional unit of ecology.  Ecology means the study of ecosystem.  An ecosystem can be defined as a group of organisms interacting among themselves and with their environment.TYPES OF ECOSYSTEM Ecosystem Artificial/Man Natural ecosystem engineered ecosystem e.g: croplands, Terrestrial dams, etc., Aquatic ecosystem ecosystem Marine ecosystem Fresh water ecosystem Lotic(running water) Lentic (standing water) ecosystem ecosystemNATURAL ECOSYSTEM  Operates themselves under natural conditions.  Based on their habitat types, it can be further classified into two types, 1) Terrestrial ecosystem related to land vegetation – grassland ecosystem, forest ecosystem, desert ecosystem , etc., 2) Aquatic ecosystem related to water and is further sub classified into 2 types based on their salt content as,  Fresh water ecosystem a) Running water ecosystem – rivers, streams. b) Standing water ecosystem – pond, lake.  Marine ecosystem – sea and sea shore.STRUCTURE (OR) COMPONENTS OF AN ECOSYSTEM • An ecosystem has two major components , 1) Abiotic (non-living) components. 2) Biotic (living) components. Abiotic component Ecosystem Biotic component Fig. 1 Components of an ecosystem and their relationshipABIOTIC COMPONENTS  The non-living components of an ecosystem  Examples – Climate, soil, water, air, energy, nutrients etc., 1) Physical components include the energy, climate, raw materials and the living space which the biotic components (living organisms) needs. Examples – air, water, soil, sunlight, etc., 2) Chemical components are the sources of essential nutrients. Examples : a) Organic substances – Protein, lipids, carbohydrates, etc., b) Inorganic substances – All micro (Al, Co, Zn, Cu) and macro elements ( C, H, O, P, N, K)BIOTIC COMPONENTS  The living organisms or the living members of an ecosystem.  The living components are made of many different species which are distinguished based on their feeding habit. It includes, 1) Autotrophic components include producers which are autotrops & they derive energy from sunlight to make organic compounds. Examples- Green plants, algae, bacteria, etc., 2) Heterotrophic components include consumers and decomposers which are heterotrophs i.e. they depend on others especially the producers for food.  The heterotrophs are a) Macro consumers – herbivores, carnivores, omnivores. b) Saprotrophs ( micro consumers) – decomposers ( bacteria, fungi, etc.,)CLASSIFICATION OF BIOTIC COMPONENTS  Biotic components are grouped into 3 groups based on their feeding habit.  Producers ( Autotrophs) synthesize their own food through photosynthesis . hv 6Co + 12 H O C H O + 6O + 6H O 2 2 6 12 6 2 2 chlorophyll  Consumers (Heterotrophs) depends on producers for their food and are of the following types: a) Primary consumers- herbivores- depends on plants for their food- plant eaters- insects, rat, goat, horse, cow , etc., b) Secondary consumers- primary carnivores- depends on 1° consumers for their food- meat eaters- frog, cat, snakes, etc.,a) Tertiary consumers- secondary carnivores - depends on 2° consumers for their food- meat eaters- tiger, lion, etc.,  Decomposers feed on dead organisms, plants & animals & decompose them into simpler compounds.  During this process inorganic nutrients are released which are then used by the producers along with other organic nutrients for preparing their own food.FUNCTION OF AN ECOSYSTEM  The function of an ecosystem is to allow flow of energy and cycling of nutrients.  Functions of an ecosystem is of 3 types : 1) Primary function of all ecosystem is manufacture of starch (photosynthesis) . 2) Secondary function is distributing energy in the form of food to all consumers. 3) Tertiary function includes decomposing the dead items and initiate the process of “cycling”ENERGY FLOW IN THE ECOSYSTEM  Energy is the most essential requirement for all living organisms.  Solar energy is the only source to our planet earth.  Of the solar radiations reached the earth’s surface, some of which is absorbed by producers (plants) to produce organic matter through photosynthesis.  The plants are used by the herbivores and the herbivores are used by the carnivores as their food.  Thus the energy enters the ecosystem through photosynthesis and passes through the different tropic levels (feeding levels).  The conversion of solar energy is governed by the law of thermodynamics. FIRST LAW OF THERMODYNAMICS o energy can neither be created nor destroyed, but it can be converted from one form to another. o Solar energy is converted into chemical energy through photosynthesis by plants.  SECOND LAW OF THERMODYNAMICS o whenever energy is transformed, there is a loss of energy through the release of heat. o This occurs when energy is transferred between tropic levels. o The loss of energy takes place through respiration, running, hunting, etc., o Respiration equation CH O + O CO + H O 2 2 2 2 Carbohydrate oxygen carbondioxide water NUTRIENT FLOW OR NUTRIENT CYCLING OR BIOGEOCHEMICAL CYCLE IN THE ECOSYSTEM  Nutrients are the elements which are essential for the survival of both plants and animals. o Macronutrients - elements needed in large amounts- O, N, C, Ca, Mg & P. o Micronutrients – elements needed in small amounts- Co, Zn, Cu, Boron & Strontium.  Nutrient cycles- the cyclic flow of nutrients between the biotic & abiotic components-. biogeochemical cycles.  The major nutrients like C, H, O & N are cycled again & again between biotic & abiotic components of the ecosystem.CARBON CYCLE  Carbon – basic component in all the organic compounds.  It is present in all biotic components in different forms such as carbohydrates, proteins, fats & aminoacids.  It is present in the atmosphere as CO 2 .  CO is taken up by green plants for photosynthesis. 2  This food moves through food chain & finally the carbon present in the dead matter is returned to the atmosphere as CO 2.  During respiration, plants & animals liberates CO in the 2 atmosphere.  Combustion of fuels also release CO 2  Volcanic eruptions also release CO 2NITROGEN CYCLE  Nitrogen is present in the atmosphere as N in large amounts (78%). 2  It is present in all biotic components in different forms such as proteins, vitamins ,aminoacids, etc.,  It is taken up by the green plants and these move through the food chain.  After the death of the plants & animals, the organic nitrogen in dead tissues is decomposed by several ammonifying & nitrifying bacteria into ammonia, nitrites & nitrates.  Nitrates again converted into molecular nitrogen (N ) which are 2 again used by the plants.  Nitrification – conversion of ammonia into nitrates by nitrifying bacteria - Nitrobacter, Nitrosomonas  Denitrification- conversion of nitrates into nitrogen by denitrifying bacteria – Pseudomonas fluorescencePHOSPHOROUS CYCLE  Phosphorous is mainly present in the rocks & fossils.  It is present in all biotic components in different forms such as bones, teeth, guano deposits.  Phosphate rocks is excavated by man for using it as a fertilizers.  The excess phosphate fertilizers move with the surface run-off, reaches the ocean & are lost into the deep sediments.  Sea birds eat sea fishes, which are phosphorous rich & the excreta of the birds return the phosphorous to the land.  Animals & plants use these dissolved phosphates during the biosynthesis.