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Welcome to Mr. Taylor's 6th Grade Science Class! This page was created to keep both students and parents connected to the classroom. Science is now everywhere.

Thursday, March 24, 2011

Unit A-Chapter 4-Lesson 3 Notes

What Happens When an Ecosystem Changes?

Environmental Changes

  • Change is a natural part of the history of any ecosystem.
  • Changes may be long-term-for example, the result of fires, droughts, and floods- or long-term, as a result of climatic change.
  • All organisms have a certain range of tolerance for conditions such as:
      1. Environmental temperature
      2. Amount of moisture 
      3. Amount of light
  • Organisms cannot usually survive in conditions that are outside their range of tolerance.
  • In any ecosystem, populations change as conditions change.
  • New communities of organisms, which are better adapted to new conditions in that ecosystem, may replace original communities.

  • Organisms can live in an ecosystem only as long as it meets their needs for food, water, shelter, and other essentials. 
  • Organisms that live within an ecosystem often compete for similar resources.
  • This competition occurs among different kinds of organisms, as well as among members of the same species.
  • Competition helps regulate population size because as competition for resources increases, population size decreases.
  • When resources are limited, organisms that are well-adapted to the conditions in an ecosystem will be best able to compete for resources and survive.
  • Some animals solve the problem of limited resources by migrating.
  • The snowy owl, for example, inhabits the Arctic tundra, but when the population of lemming-their main food source-falls, it may migrate great distances in search for food. 
  • In the winter, snowy owls are sometimes sighted as far south as Illinois.

People Affect Ecosystems

  • Ecosystems change naturally, but human activities such as cutting down trees and draining wetlands can speed up the change.
  • People can also change the ecosystems by introducing new species that out-compete native species.
  • Conservation of resources and restoration practices can help to reduce and repair ecosystem damage.

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