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Ecosystem Dynamics Food Chains and Food Webs

Ecosystem Dynamics Food Chains and Food Webs. Maroochydore SHS. Energy in Ecosystems. Energy that sustains majority of living systems is solar energy Solar energy is converted to chemical energy in photosynthesis and is held briefly in the biosphere before it is radiated into space as heat.

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Ecosystem Dynamics Food Chains and Food Webs

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  1. Ecosystem DynamicsFood Chains and Food Webs Maroochydore SHS

  2. Energy in Ecosystems • Energy that sustains majority of living systems is solar energy • Solar energy is converted to chemical energy in photosynthesis and is held briefly in the biosphere before it is radiated into space as heat

  3. Getting Energy • Autrotrophs (Producers) produce their own food using the suns energy (Photosynthesis) • Autrotrophs are eaten by other organisms, which in turn are eaten • This is how food passes through ecosystem Food chain = the path that food takes from organism to organism

  4. Based on the way they obtain food, the organisms can be classified in three groups: • Producers • Consumers • Decomposers

  5. Producers (Autotrophs) • Convert simple inorganic chemicals to complex organic molecules (food) • Most use solar radiation (sun) as a source Productivity = measured by the amount of energy that is fixed in chemical compounds or by increase in biomass in a particular length of time

  6. Example of a Producer… • Plants… • Utilize energy from the sun and nutrients from the abiotic environment (carbon dioxide from the air or water, other nutrients from the soil or water) • Result = photosynthesis

  7. Consumers • Used food by other organisms as their energy source • Three levels of consumers: • First-order (Primary) are herbivores • Second-order (Secondary) eat first- order consumers (carnivores which eat herbivores) • Third (Tertiary) and higher order eat second-order consumers (carnivores which eat other carnivores)

  8. Decomposers • Most are simple forms of life (bacteria, fungi and some protozoans) • These break down the dead bodies and waste products of other living things • Convert complex organic molecules into simple inorganic chemical which are then released into the environment and can be reused

  9. Food Chain • Simple linear series that shows the series of organisms existing in any ecosystem • Can be described as a transfer of energy • Each organism in the series feeds on and obtains energy from the preceding organism and provides energy to the next organism • Trophic (feeding) levels describe the relative positions of producers and consumers in a food chain

  10. Food Chains • A food chain shows what a set of organisms in an ecosystem eats with each organism acting as a link in the chain. • Each link is called a trophic level. • Arrows connect each level and point in the direction in which the food is going. • Energy flows through an ecosystem from plants (producers) to herbivores (primary consumers to carnivores (secondary consumers) The ant is eaten by the bird.

  11. There are rarely more than 6 links in any food chain • This is because energy is lost to the environment in the form of heat at each level of a food chain • The closer a consumer is to the producer, the more efficient is the energy transfer

  12. Food chains always start with the sun and then a plant. The lettuce is eaten by the slug, the slug is eaten by the bird.

  13. The top of the food chain. Some animals are said to be at the top of the food chain. This is because they are not hunted by other animals. No other animal hunts the lion. The lion is at the top of the food chain. Can you think why?

  14. Food Webs • Displays the interactions between organisms in a community • In a food web there is greater stability since a variety of food sources compensates for seasonal fluctuations • All waste and dead materials are acted upon by decomposers

  15. Law of Conservation of Matter and Energy Ecosystems conform to this law which states that: “matter and energy cannot be created or destroyed but can be changed to other forms”

  16. Ecological Pyramids • May be: • Pyramid of numbers • Showing the #s of individual organisms at each level • Pyramid of biomass • Based on the total dry mass of the organisms at each level • Pyramid of energy • Showing the productivity of the different levels Large amounts of energy and biomass are dissipated at every trophic level

  17. Pyramid of Numbers This pyramid illustrates that when the primary producers (leaves) are small, a large quantity of them is required to support the primary consumers (herbivores)

  18. Pyramid of Energy availability The relationship of the flow of Energy in the ecosystem - represented here by an inverted pyramid. Generally only 10% of the energy of each trophic level is passed on as energy to the next, higher level

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