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Biology Agendas:

Agenda 9/25/00

  1. Question: Define Ecosystem, Habitat, Niche
  2. Homework Check
  3. Components of an Ecosystem
    1. Physical
    2. Biological
  4. Sweet Fresh Water


Ecosystem: A habitat and the species living there.

Habitat: A place where a species lives, the physical environment where you will find a species.

Niche: A species job, what it does to survive.

Homework Check:


  1. Ecosystems
  2. Living Things are dependent upon each other.
    1. Ecology
    2. Study of how living things (organisms) interact with each other and their habitat.
    3. Habitat
      1. The physical environment, the place where an organism lives.
    4. Community
      1. All species that live in the same area.
    5. Ecosystem
      1. The community and the physical aspects of the habitat (the environment).
    6. Inhabitants of an Ecosystem
    7. Species Diversity (biodiversity)
      1. The number of species living within an ecosystem.
        1. Temperate Forest
          1. Species
            1. Animals
              1. Black Bear, white-tailed deer, cougar, red wolf, raccoons, foxes, gray squirrels, rabbits, chipmunks, lizards, red-tailed hawks, turkey vultures, turkeys, quail, catfish, bass, perch, turtles, earthworms, flatworms.
            2. Plants
              1. Trees, shrubs, vines, ferns, mosses, gasses, flowers.
            3. Other Life
              1. Fungi
              2. Protists
              3. Bacteria
          2. Environment
            1. Soil, rocks, water, wind, temperature, sunlight
      2. Boundaries of an Ecosystem
        1. Depends upon what the scientist is studying
          1. Log, meadow, pond, lake, etc.
        2. No single system is totally isolated from other systems and places.
    8. Natural Changes in Ecosystems Cycles
      1. Volcanoes, fire, glacier expands or recedes
      2. Succession
        1. Regular progression of species replacement.
          1. Grasses replaced by shrubs.
          2. Shrubs replaced by small trees.
          3. Small trees replaced by larger, fatter trees.
        2. Primary succession
          1. Succession occurring on land, where nothing has grown before.
        3. Secondary succession
          1. Succession occurring where plants have grown before.
        4. Climax community
          1. The final stage of succession.
            1. Hypothetical, a theory, only.
            2. Natural disasters starts the succession cycle again.
            3. No two successions are alike, so a habitat would not reach the same climax community again.
      3. Glacier Bay
        1. Glacier receding (melting) for the last 200 years.
        2. For 10 years, nothing grows where the glacier has receded.
          1. Lack usable nitrogen needed for plants and animals
        3. Dryas starts primary succession.
          1. Have mycorrhizae that can change the form of the nitrogen so Dryas can use it.
        4. Seeds of alder and grasses blown in by wind start the second stage.
          1. Alder can fix nitrogen, making it useful.
        5. After 80 years, Sitka spruce invades the habitat.
          1. Sitka spruce use the nitrogen freed by the alder.
        6. Hemlock trees follow the spruce into the habitat.
          1. More shade tolerant, so they grow well under the spruce's shadow.
        7. Now it's a Hemlock-Spruce community.

Questions 1-3

    1. All the nonliving components of an ecosystem (water, solid, and rocks) are not part of a community.
    2. Since many of the organisms in an ecosystem are inconspicuous (hide) or small, equipment that would help locate these organisms would be most helpful. For instance, a shovel could be used to dig up soil-dwelling organisms. A drill could help bore into trees after boring worms and insects.
    3. Lawns would proceed through succession if they were not regularly mowed.
    4. Where is crayfish discussed in the textbook?

Page 686-687.

Class Notes:






(All species living


(Home, place where

in an area, habitat)


species live)



Physical Environment

Food Web (Eatting)













Soil, rocks



Chemical Composition


ì Nitrogen


ï Oxygen



í Carbon


ï Phosphorus


ï Hydrogen


î Sulfur







Alaska and North












The top predators are People and Wolves.