1. Ecosystems and Ecosystem Management
Chapter 6
Ecosystems and Ecosystem Management
Botkin and Keller Environmental Science 5e

2. Basic Characteristics of Ecosystems
Sustained life on Earth is a characteristic of ecosystems, not of individual organisms or populations- no member of a community can carry out the processes of life alone
Structure: An ecosystem is made up of two major parts:
Non-Living (Abiotic)- Physical Environment (Soil, Air and Water)
Living (Biotic)- Ecological community
Botkin and Keller Environmental Science 5e

3. Basic Characteristics of Ecosystems
2) Processes: Two basic kinds of processes must occur in an ecosystem: a cycling of chemical elements and a flow of energy
3) Change: An ecosystem changes over time and can undergo development through a process called succession
Botkin and Keller Environmental Science 5e

4. Ecological Communities and Food Chains
A set of interacting species that occur in the same place and function together to make possible the persistence of life
Energy, chemical elements and some compounds are transferred from creature to creature along FOOD CHAINS/FOOD WEBS (Linkage of who feeds on whom)
Botkin and Keller Environmental Science 5e

5. Botkin and Keller Environmental Science 5e
Trophic Levels
A trophic level consists of all those organisms in a food web that are the same number of feeding levels away from the original source of energy.
The original source of energy in most ecosystems is The Sun.
Botkin and Keller Environmental Science 5e

6. Food Chains and Food Webs
A Terrestrial Food Chain
4 trophic levels:
Autotrophs (Photosynthesizing plants, algae and bacteria)
Herbivores (Plant-Eaters)
Carnivores (Feed directly on Herbivores)
Carnivores (Feed on other Carnivores) and Decomposers (Bacteria and Fungi-Feed on everything)
People are Omnivores (Herbivore & Carnivore)
Botkin and Keller Environmental Science 5e

7. Botkin and Keller Environmental Science 5e

8. Botkin and Keller Environmental Science 5e

9. Botkin and Keller Environmental Science 5e
The Community Effect
Species interact directly and indirectly
Community-level interactions
Example: Sea Otters of Pacific Ocean
Otters eat Sea Urchins
Sea Urchins eat kelp (important habitat for many creatures)
More Sea Otters= Less Sea Urchins= More Kelp Forests for many sea creatures
Botkin and Keller Environmental Science 5e

10. Botkin and Keller Environmental Science 5e
Keystone Species
A species such as the Sea Otter that has a large effect on its community or ecosystem is called a Keystone Species
Removal or change in the role of a keystone species within the ecosystem changes the basic nature of the community
Botkin and Keller Environmental Science 5e

11. Botkin and Keller Environmental Science 5e
Community Interactions with Sea Otter
Botkin and Keller Environmental Science 5e

12. Botkin and Keller Environmental Science 5e
Oceanic Food Web
Botkin and Keller Environmental Science 5e

13. Botkin and Keller Environmental Science 5e
Food Web of Harp Seal
Botkin and Keller Environmental Science 5e

14. Natural and Artificial Ecosystems
Ecosystems can be natural or artificial or a combination of both
Agriculture can be thought of as partial management of certain kinds of ecosystems
Wildlife Preserves are examples of partially managed ecosystems
Botkin and Keller Environmental Science 5e

15. Botkin and Keller Environmental Science 5e
Review Questions
1) What is the difference between an ecosystem and an ecological community?
2) In what ways would an increase in the number of sea otters and a change in their geographical distribution benefit fisherman? In what ways would these changes be a problem for fisherman?
Botkin and Keller Environmental Science 5e

16. Botkin and Keller Environmental Science 5e
Review Questions
3) Based on the discussion in this chapter, would you expect a highly polluted ecosystem to have many species or few species?
4) Is our species a keystone species? Explain.
Botkin and Keller Environmental Science 5e