Sept. 9th 2011
Ecology: Communities Continued
Ms. Walker’s Biology Class
✤ 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
Review✤ Communities depend on their environment.
✤ Environments are made up of biotic & abiotic factors.
✤ These factors can be limiting factors, which limits population
✤ Once resources have been used up (limiting factors), a population
will hit it’s carrying capacity.
✤ 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.
✤ 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.
How does the story end?
✤ Climax Community: A forest that has reached maturity. Longer-
living carnivores probably occupy the area, as well as large
✤ Create a story about the life of an ecosystem. You should use the
✤ 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
✤ Due Wednesday, Sept. 11th