Chapter 48 - Ecosystems

Ecosystem

• all of the organisms (community) and their nonliving environment in a defined area

• energy flows in one direction

• nutrients cycle

Flow of Energy

• source of all energy for life on Earth - sunlight

• sunlight is captured in photosynthesis

• energy moves from one trophic level to the next

  • primary producers

  • consumers

  • decomposers

• food chain

• food web

• there is loss of energy at each transfer

• ecological pyramid

Flow of Nutrients

• nutrients cycle between the living community and the physical environment - biogeochemical cycles

  • hydrologic cycle

    • reservoir: oceans

    • Figure 48.9

    • effects of deforestation on nutrient loss

  • carbon cycle

    • needed for all organic molecules

    • reservoirs: carbon dioxide in atmosphere and oceans

    • also stored in fossil fuels and calcium carbonate of shells

    • Figure 48.10

  • greenhouse effect and global warming

    • greenhouse effect: build up of heat near the Earth's surface due to gases in the lower atmosphere

    • higher CO₂ result of alteration in the carbon cycle

    • other greenhouse gases: methane, CFC's

    • greenhouse effect results in global warming

    • evidence for greenhouse effect and global warming

  • nitrogen cycle

    • needed for nucleic acids and proteins

    • reservoir: atmosphere

    • Figure 48.12

  • phosphorus cycle

    • needed for ATP, nucleic acids, phospholipids

    • reservoir: phosphate in rock

    • Figure 48.15

    • eutrophication

© Carol L. Wymer, 2004