botkin and keller environmental science 5e chapter 6 ecosystems and ecosystem management

Botkin and Keller Environmental Science 5e

Chapter 6

Ecosystems and

Ecosystem Manageme

nt

Botkin and Keller Environmental Science 5e

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

1) 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

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

Ecological Communities and Food Chains

Ecological Communities:1) 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

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

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

Botkin and Keller Environmental Science 5e

Botkin and Keller Environmental Science 5e

The Community Effect

• Species interact directly and indirectly

• Community-level interactionsExample: 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

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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

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Community Interactions with Sea Otter

Botkin and Keller Environmental Science 5e

Oceanic Food Web

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Food Web of Harp Seal

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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

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

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.