How Ecosystems Work
Homework:
• Chapter 5: Read Pages 117-123
• Define Key Terms (pg. 117):
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Photosynthesis
Producer
Consumer
Decomposer
Cellular Respiration
Food Chain
Food Web
Trophic Level
Hierarchy of Life
• Simple  Complex
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Atom
Molecule
Organelle
Cell
Tissue
Organ
Body System
Organism
Population
Community
Ecosystem
ACTIVITY: What’s the story?
First Principle of Ecology
Interconnectedness
Ecological Concepts
– The way organisms interact w/ each other and w/
nonliving surroundings.
Ecosystem
A group of plants, animals and microbes interacting
with each other and the physical environment in a
sustainable way.
How big is an ecosystem?
Types of Ecosystems
Biomes: large terrestrial ecosystems
Biosphere
• Earth’s “super ecosystem” includes all life forms and
the physical environments supporting life.
• Includes: air, land, surface rocks, and water w/in
which life occurs, and which biotic processes take
place!
Ecological Concepts
Ecological Concepts
• Limiting Factors
– Factors that are critical
to a species’ success.
– Abiotic or Biotic
Range of Tolerance
• Trout
– Live in fast flowing, cold
water
– More dissolved oxygen
• Black Bass
– Adapted to lower oxygen
concentrations and higher
water temperatures
• Limiting Factors: water
temperature and dissolved
oxygen
Ecological Concepts
• Habitat and Niche
– Habitat
• Space organism lives
– (its address)
– Niche
• Functional role it has in its
surroundings
– (its profession)
– Ex: Beaver
• Flooding, kills trees,
enhances environment for
other animals, and is a food
source for predators.
Categories of Organisms
(common to every ecosystem)
• Autotrophs (producers)
– Self-feeding
– Typically, green plants
Categories of Organisms
(common to every ecosystem)
• Heterotrophs
– Consumers
– Must eat others
– 5 Types:
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Herbivores
Carnivores
Omnivores
Decomposers (bacteria
and fungi)
• Detritus Feeders
(scavengers)
Feeding Relationships
• Predator-prey
– One organism kills and eats
another
• Grazing
– Herbivore-producer
• Host-Parasite
– Parasite lives in host to derive
nourishment.
– Host is generally harmed, but
not killed immediately.
Energy Flow Through Ecosystem
• Food Chains
– Show direction of energy
flow b/w organisms in an
ecosystem
– Bioaccumulation: build
up of toxins in the food
chain.
Energy Flow Through Ecosystem
• Food Web
– Shows all possible pathways
Energy Flow Through Ecosystem
Trophic Levels
Biomass Pyramid
Biomass Pyramid Continued
• Shows the relative proportions of biomass at each
trophic level.
• In most efficient ecosystems, there is only about
10% of food energy available for the next higher
trophic level– what happened to the other 90%?
• Food chains in most terrestrial ecosystems rarely go
higher than 4 trophic levels.
Activity