3.2 Communities (Page 95-99) Homework: Page 99 # 1, 4, 5 Key Concepts: (Page 99)

Species live in communities where relationships among different species are very important. Dominant species are very common primary producers

Keystone species are especially significant in maintaining an ecosystem through their relationships with other species. Odd Animal Couples

Ecosystem engineers alter a landscape in a way that makes it suitable for additional species. Succession is the series of changes in an ecosystem that occurs over time, following a disturbance.

Important species in a Community: 1.What are the two types of species that affect communities? The two types are dominant species and keystone species. 2. All the different organisms on the right live in a pond ecosystem. Which of these species do you think is the dominant species? The dominant species are grass, weeds and trees.

3. What will happen to this community if the dominant species is removed? The removal of a dominant species can result in the decrease in biodiversity within an ecosystem.

4. Describe what happened with the North American forests around The American chestnut was a dominant tree in eastern North America. In 1950, all American chestnut trees had been killed as a result of a fungus that had been accidentally introduced. As a result, seven species of insects that relied on the trees as a source of food became exinct.

Keystone Species: 5. What is a keystone species? A keystone species is a species that can generally affect population numbers and the health of an ecosystem. They are generally not abundant but play a significant role.

6. List examples of keystone species and explain why they are classified as keystone species. Prairie Dogs – Build underground burrows, turning over tonnes of soil, which increases the nitrogen content and helps channel rainwater into the water table to prevent runoff and erosion. This allows the soil to support a greater variety of plants and animals. Beavers – Act like ecosystem engineers and transform their territory from a stream, to a flooded forest, then to a pond or swamp.

7. What is the purpose of captive breeding program? Captive breeding is the breeding of rare or endangered wildlife in controlled settings to increase the population size and prevent their extinction. 8. Why are beavers called, “ecosystem engineers”? Ecosystem engineers are a species that can cause dramatic changes to a landscape that it creates a new ecosystem. By building dams, beavers can convert a stream ecosystem to a pond ecosystem.

9. Explain succession in your own words? Succession is the series of changes in an ecosystem that occurs over time, following a disturbance.