Community Ecology 3.1

Remember what a community is? Biosphere- most broad level Biome Ecosystem Biological Community (Or just community) Population Organism –most basic level Biological Community- several different populations interacting together at the same geographic location. Ex: Teachers are a different group of people, Custodians are a different group of people, Cafeteria workers are a different group of people all interacting with the students at Sweetwater High School.

Ecology of communities Limiting Factors- any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms. Ex: I have two boxes of cake mix. Each cake mix calls for 3 eggs. Therefore, I need 6 eggs if I want to make both cakes. I only have 5 eggs, so my eggs are the limiting factor and I can only make one cake. On a more ecology note… every frog needs to eat 3 grasshoppers a day to survive. There are 100 frogs in a pond but only 270 grasshoppers. Therefore, 10 frogs will die. The grasshoppers are the limiting factor.

Ecology of communities Tolerance- the ability of an organism to survive when subjected to abiotic or biotic factors, or lack thereof. Ex: Humans can survive if their body temperature is between 95- 106 ° F. We cannot tolerate anything more or less before it becomes detrimental.

Ecological Succession When abiotic and biotic factors change outside of a community’s tolerance level, the community will slowly change into another one. When this happens, it’s called Ecological succession. Ex: Forest fires or volcanic eruption wipes out a forest, eventually it will grow back through a specific series of events.

Process of Ecological succession

Process of ecological succession Primary succession- the establishment of a community in an area of exposed rock that does not have any topsoil. This occurs very slowly at first. Lichens and other fungi will form on bare rock which will eventually create the soil that is needed for plants. Primary succession is a process that occurs after a specific natural disaster such as a volcanic eruption, which kills all soil and leaves nothing but bare rock.

Process of ecological succession Secondary succession- Similar to primary succession but occurs only when soil has been left intact. This type of succession occurs in a very orderly and predictable manor.

Key Points Like other things, Ecosystems have limits of tolerance that they can handle before they begin to die. When ecosystems do die, they will be replaced by either primary or secondary succession.