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Ecosystems and Energy

Ecosystems and Energy. 3. Overview of Chapter 3. What is Ecology? The Energy of Life Laws of Thermodynamics Photosynthesis and Cellular Respiration Flow of Energy Through Ecosystems Producers, Consumers & Decomposers Ecological Pyramid Ecosystem Productivity. Ecology. Ecology

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Ecosystems and Energy

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  1. Ecosystems and Energy 3

  2. Overview of Chapter 3 • What is Ecology? • The Energy of Life • Laws of Thermodynamics • Photosynthesis and Cellular Respiration • Flow of Energy Through Ecosystems • Producers, Consumers & Decomposers • Ecological Pyramid • Ecosystem Productivity

  3. Ecology • Ecology • “eco” house & “logy” study of • The study of interactions among and between organisms in their abiotic environment • Biotic - living environment • Includes all organisms • Abiotic - non living or physical environment • Includes living space, sunlight, soil, precipitation, etc.

  4. Ecology • Ecologists are interested in the levels of life above that of organism

  5. Ecology Definitions • Species - A group of similar organisms whose members freely interbreed • Population - A group of organisms of the same species that occupy that live in the same area at the same time • Community - All the populations of different species that live and interact in the same area at the same time • Ecosystem - A community and its physical (abiotic) environment • Landscape - Several interacting ecosystems

  6. Ecology • Biosphere contains earth’s communities, ecosystems and landscapes, and includes: • Atmosphere- gaseous envelope surrounding earth • Hydrosphere- earth’s supply of water • Lithosphere- soil and rock of the earth’s crust

  7. Energy • The ability or capacity to do work • Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below)

  8. Energy • Energy exists as: • Potential energy (stored energy) • Kinetic energy (energy of motion) • Potential energy is converted to kinetic energy as arrow is released from bow

  9. Thermodynamics • Study of energy and its transformations • System- the object being studied • Closed System- Does not exchange energy with surroundings (rare in nature) • Open System- exchanges energy with surroundings

  10. Laws of Thermodynamics • First Law of Thermodynamics • Energy cannot be created or destroyed; it can change from one form to another • Second Law of Thermodynamics • When energy is converted form one form to another, some of it is degraded to heat • Heat is highly entropic (disorganized)

  11. Photosynthesis • Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of sugar molecules 6 CO2 + 12 H2O + radiant energy C6H12O6 + 6 H2O + 6 O2

  12. Cellular Respiration • The process where the chemical energy captured in photosynthesis is released within cells of plants and animals • This energy is then used for biological work C6H12O6 + 6O2 + 6 H2O 6 CO2 + 12 H2O + energy

  13. Photosynthesis and Cellular Respiration

  14. Energy Flow Through Ecosystems • Passage of energy through an ecosystem

  15. Food Chains- The Path of Energy Flow • Energy from food passes from one organisms to another based on their Trophic Level • Def: An organism’s position in a food chain, which is determined by its feeding relationships • First Trophic Level: Producers • Second Trophic Level: Primary Consumers • Third Tophic Level: Secondary Consumers • Decomposers are present at all trophic levels

  16. Food Web

  17. Ecological Pyramids • Graphically represent the relative energy value of each trophic level • Important feature is that large amount of energy are lost between trophic levels to heat • Three main types • Pyramid of numbers • Pyramid of biomass • Pyramid of energy

  18. Pyramid of Numbers • Illustrates the number of organisms at each trophic level • Fewer organisms occupy each successive level • Does not indicate: • biomass of organisms at each level • amount of energy transferred between levels

  19. Pyramid of Biomass • Illustrates the total biomass at each successive trophic level • Biomass: measure of the total amt of living material • 90% reduction in biomass through trophic levels

  20. Pyramid of Energy • Illustrates how much energy is present at each trophic level and how much is transferred to the next level • Most energy dissipates between trophic levels • Explains why there are so few trophic levels

  21. Ecosystem Productivity • Gross Primary Productivity (GPP) • Total amount of energy that plants capture and assimilate in a given period of time • Net Primary Productivity (NPP) • Plant growth per unit area per time • Represents the rate at which organic material is actually incorporated into the plant tissue for growth • GPP – cellular respiration = NPP • Only NPP is available as food to organisms

  22. Variation in NPP by Ecosystem

  23. Human Impact on NPP • Humans represent 0.5% of land-based biomass, but use 32% of land-based NPP! • This may contribute to loss of species (extinction) • This represents a threat to planet’s ability to support both human and non-human inhabitants

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