1. Unit 2: Interactions in Ecosystems
Chapter 4: Ecosystems
Lesson 4.1
T.O.C:
What are Ecosystems?

2. Ecosystems
Ecosystem(w.w)- area where organisms interact w/ one another as well as w/ the nonliving parts of the environment. Ex: pond, river, forest, desert
Can be as large as a lake or forest or as small as a mud puddle or rotting log (pillbugs)
Ecosystems have both biotic & abiotic parts.
Biotic = living parts of ecosystem. Ex: trees, animals, trees
Biotic parts interacts w/ one another. Ex: Squirrel/birds & trees
These parts help shape the environment. Roots split rock & anchor soil, moles & prairie dogs change the ground shape
Abiotic= nonliving parts of ecosystem. Ex: climate, water, air
These parts help determine what lives in the ecosystem. Think about the different climates in the world.

4. A Place to Live
Remember: there are different types of plants & animals in an ecosystem…
Population(w.w)- group of organisms of the same species living together in an ecosystem.
In a forest you might see a nest of squirrels in a tree, a hive of honeybees, or grove of oak trees. Each are populations
Community(w.w)- all the populations living in an ecosystem. The populations of a community interact by using one another for both food & shelter.
Habitat(w.w)- part of the ecosystem in which an organism lives. (just like you live in YOUR house, wolves have dens, etc.)
The habitat supplies what the organism needs- heat, light, water, food, & shelter
2 pop.s w/ similar needs can share a habitat (owls/hawks) but not a niche
Niche(w.w)- an organisms role in an ecosystem. So, everything it needs & everything it does. Includes interaction w/ biotic & abiotic
Organisms can have broad niches or narrow niches.
Broad= live in a lot of places. Mice, raccoons, mountain lions, wolves, people
Narrow= live in one particular habitat. Penguins, polar bears, arctic fox
If 2 pop.s in ecosystem have same niche then they must compete for resources

6. Diversity
Ex: hummingbirds drink nectar from flowers, so they would need flowers for food, feed small spring flies tot heir young, and line their nests w/ the downy leaves of the mullein plant. Therefore, all these must be present in an ecosystem w/ hummingbirds.
Diversity(w.w)- variety of species in an ecosystem.
Some ecosystems are very diverse while others have just a few different species.
Why is this?? There are 2 reasons:
Climate & location!
In general, ecosystems closer to the equator have more species & so are more diverse. Ecosystems closer to Earth’s poles have fewer species & so they are less diverse.
Actions of ppl are making ecosystems less diverse.

7. 4.1 Review Q’s
Why are climate and location the two most important factors in determining ecosystem diversity? (2 points)
What is an organisms niche? (2 points)
How are population & community related in an ecosystem? (2 points)
What are the biotic and abiotic parts of an ecosystem? (2 points)
What is an ecosystem? Give an example of at least one.