STRUCTURE AND FUNCTION OF ECOSYSTEM<br />Presented by: HALAI DAXA D. M.Sc. (Environmental) Sem-1<br />KSKV unevirsity<br />Paper 102/c unit 2<br />
WHAT IS AN ECOSYSTEM ?<br /><ul><li>The term ecosystem was first proposed by A.G.Tansley in1935.
He defined it as “the system resulting from the integration of all the living and non- living factors of environment”.
Ecosystem is most preferred, where ‘eco’ implies the environment, and ‘system’ implies an interacting, inter-dependent complex.
Thus any unit that includes all the organisms i.e. the communities in a given area, interact with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity and material cycle within the system, known as an ecological system or ecosystem.</li></li></ul><li><ul><li> An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving, physical components of the environment with which the organisms interact, such as air, soil, water and sunlight.
The structure and function are the major aspects of an ecosystem.</li></li></ul><li>STRUCTURE OF AN ECOSYSTEM<br /><ul><li>the composition of biological community including species, numbers,biomass, life history and distribution in space, etc.
the quantity and distribution of non living materials like nutrients, water etc.
the conditions of existence such as temperature, light etc.
The structure of an ecosystem is characterized by the organization of abiotic and biotic components.</li></li></ul><li>a<br />bios<br />= abiotic<br />without<br />life<br />without life<br />abiotic components.<br />Inorganic substances<br />Organic substances<br />Climatic factors<br /><ul><li>carbon cycle
The conversion of ammonium to nitrate is performed primarily by soil-living bacteria and other nitrifying bacteria.
the oxidation of ammonium(NH4+) – by bacteria Nitrosomonas species the nitrites – BY Nitrobacter</li></li></ul><li><ul><li> Denitrification
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle.
is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions
They use the nitrate as an electron acceptor in the place of oxygen during respiration.</li></ul>NO3- NO2- N2O N2<br />
Organic substances<br /><ul><li> These includes lipids, proteins, carbohydrates.
Which are formed by biotic components and that are linked with biotic components.
They have a strong influence on structure behavior and inter relationship of various organisms in an ecosystem. </li></li></ul><li>biotic components.<br />Producers <br /><ul><li> They are generally chlorophyll bearing autotrophic(self + feeding.)organisms which prepare </li></ul>organic compounds from inorganic raw materials . Eg. green plants and some photosynthetic bacteria.<br />
Consumers<br />They are also called heterotopyhs which means those who feed on others . <br />Herbivores<br /><ul><li> Organisms that eat plants are called primary consumers
Primary consumers are herbivores – the only eat plant material</li></li></ul><li>Carnivores<br /><ul><li> These are the animals which feeds on herbivores.</li></li></ul><li>Omnivores<br /><ul><li> They consume both plants and animals.</li></li></ul><li>Decomposers<br /><ul><li> Decomposers are organisms that degrade or decompose dead or organic material in simpler molecules.
Fungi and bacteria are decomposers</li></li></ul><li>FUNCTION OF AN ECOSYSTEM<br /><ul><li>Ecosystem have some functional attributes which keep the component parts running together.
For example – green leaves prepare food & roots absorb nutrients from the soil. Herbivores feed on part of the plant production, and in turn serve as food for carnivores.
Decomposers carry out the function of braking down complex organic materials into simple inorganic product which can be used by the producers.
All these functions in an ecosystem occur through delicately balanced and controlled processes.
Thus, this cycle goes on and on, leading to efficient continuous functioning of the ecosystem.</li></li></ul><li><ul><li> Food chain, food web and trophic structure
Ecosystem development and regulation</li></li></ul><li>Food Chains<br /> “Transfer of food energy through a series of different organisms in the ecosystem is called food chain”<br /><ul><li> Food chain in simple term is a linked feeding series.
A single food chain should have at least three links to be complete.
Phytoplanktons water fleas small fish Carnivorous fish (Pond ecosystem)
Lichens reindeer Man (Arctic tundra)</li></li></ul><li>Two major types of food chains:<br />1. Grazing food chain<br /><ul><li> It starts with green plants (primary producers) and culminates in carnivores.
Phytoplanktons water fleas small fish Carnivorous fish (Pond ecosystem)</li></ul>2. Detritus food chain:<br /><ul><li> It starts with dead organic matter which the detritivores and decomposers consume.
Thus grazing food chain derives its energy basically from plant energy while in the detritus food chain it is obtained primarily from plant biomass, secondarily from microbial biomass and tertiarily from carnivores.</li></li></ul><li>Food Web<br />Thus food web is a network of food chains where different types of organisms are connected at different trophic levels, so that there are a number of options of eating and being eaten at each trophic levels.<br />
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