Sept. 9th 2011

Ecology: Communities ContinuedMs. Walker’s Biology Class

Review

✤ What is a population? All organisms of the same species living together in a particular area.

✤ What is a community? All of the populations of plants & animals that interact together living in a particular geographic area.

✤ Populations depend on one another for food and shelter (among many things) This is called interdependency.

Review✤ Communities depend on their environment.

✤ Environments are made up of biotic & abiotic factors.

✤ These factors can be limiting factors, which limits population growth.

✤ Once resources have been used up (limiting factors), a population will hit it’s carrying capacity.

Relationships between populations✤ Most common is predator-prey

✤ Parasitism- when one organism benefits, while the other is harmed.

✤ Mutualism- Both organisms benefit from the relationship.

✤ Commensalism- One organism benefits, while the other neither benefits nor is harmed.

Ecological Succession

✤ Do things always stay the same once an ecosystem is established?

✤ Not quite...

✤ "Ecological succession" is the observed change in the structure of an ecological community over time.

✤ Can occur due to population changes, or drastic disruptions such as forest fires, volcanic eruptions, extreme drought, etc.

Primary & Secondary Succession

✤ Primary succession: the pioneer stage starts when organisms invade a previously unoccupied area.

✤ Secondary succession: the pioneer stage begins when organisms invade an area that's already been occupied.

Secondary Succession

Differences

How does the story end?

✤ Climax Community: A forest that has reached maturity. Longer-living carnivores probably occupy the area, as well as large hardwoods.

Homework✤ Create a story about the life of an ecosystem. You should use

the following words:

✤ Primary Succession, Secondary Succession, Climax Communities, Biotic Factors, Abiotic factors, herivores, omnivores, carnivores, community, population, biome.

✤ You need to pick a biome for your story to take place (i.e. tundra, temperate forest, desert, rain forest) & describe what is in that biome.

✤ Explain what happened- is it a new community? Or one that was disrupted? How long does the ecosystem take to recover and mature into a climax community?

✤ Include 6 hand-drawn or printed pictures- 1 for each slide on worksheet.

✤ Due Wednesday, Sept. 11th