Chapter 5 How Ecosystems Work

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Chapter 5How Ecosystems Work
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Lake Victoria

• Freshwater lake in Africa
• Formerly home to 400 species of cichlids
• 1960 Nile perch
• introduced
• 1990 water hyacinth
• invaded
• Today, ecological
• imbalance why?

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What Is Ecology?

• Literally study of ones house
• Interactions
• Two components
• Biotic
• Abiotic
• Broadest biological field of study

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Ecological Organization

• Organism
• Population
• Community
• Ecosystem
• Landscape
• Biosphere

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Goals Of Ecologists

• Understand how ecosystems function
• Make connections landscape ecology
• Connections among ecosystems
• Great blue heron

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Energy

• Capacity or ability to do work
• Flows through ecosystems
• Why do organisms need energy?
• Different kinds

Potential energy
Kinetic energy
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First Law of Thermodynamics

• Energy cannot be created or destroyed
• Energy can be changed from one form to another

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Second Law of Thermodynamics

• When energy is changed from one form to another,
  some is degraded into heat
• Heat is a less usable form of energy
• Increases entropy in the universe

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Ecosystem Composition

• Producers
• Consumers
• Decomposers

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Producers

• Make their own food
• Photosynthesis
• Examples?

6CO2 6H2O ------gt C6H12O6 6O2
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Consumers

• Feed on other things
• Herbivores
• Carnivores
• Omnivores
• Detrivores

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Decomposers

• Break down dead organisms and waste products
• Examples?

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Energy Flow

• Energy passes from one organism to the next
• Trophic level each step in this flow of energy
• Food chain straight path
• Food web
• Interconnected food chains
• More realistic than food chain why?

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Food Chain
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Food Web
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Biogeochemical Cycles

• Matter cycles through ecosystems
• Five cycles
• Carbon
• Hydrologic (water)
• Nitrogen
• Sulfur
• Phosphorus

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Carbon Cycle

• Essential component for life
• Gas (CO2) in atmosphere
• Several forms in ocean
• Can take a long timethink fossil fuels

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Carbon Cycle
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Hydrologic Cycle
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Nitrogen Cycle

• Proteins, DNA
• Atmosphere is 78 N2
• Five steps
• Nitrogen fixation
• Nitrification
• Assimilation
• Ammonification
• Denitrification

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Nitrogen Fixation

• Specialized bacteria
• Split atmospheric nitrogen and combine it with
  hydrogen

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Nitrogen Cycle
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Sulfur Cycle

• Underground sedimentary rocks and minerals
• Erosion releases compounds to ocean
• Volcanoes
• Essential component of proteins

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Sulfur Cycle
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Phosphorus Cycle

• No atmospheric component
• Phosphates used in DNA and ATP (chemical energy)
• Phosphates move through the food chain

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Phosphorus Cycle
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Ecological Niche

• Everything about an organism
• Adaptations
• Use of resources
• Lifestyle
• Habitat

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Ecological Niche

• Two species cannot occupy the same niche why?
• Resource partitioning
• Reduces niche overlap
• Reduces competition

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Resource Partitioning At Work!
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Species Interactions

• No species lives in complete isolation
• Symbiosis
• Intimate relationship between members of at least
  2 species
• Mutualism, commensalism, parasitism
• Result of coevolution
• Other interactions
• Predation, competition

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Mutualism

• Both species benefit

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Commensalism

• One species benefits, other not affected

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Parasitism

• Parasite benefits, host is harmed
• Ectoparasites endoparasites

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Species Interactions

• Predation consumption of one species by another
• Coevolution arms race

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Avoiding Predators

• Mechanical defenses
• Social groups
• Camouflage
• Protective chemicals

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Species Interactions

• Competition two or more organisms attempting to
  use the same resource
• Intraspecific vs. interspecific

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Keystone Species

• Crucial to maintenance of an ecosystem
• Loss affects many other
• species
• Examples?
• This idea is being
• challenged why?

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Case Study Global Climate Change

• Atmospheric CO2 increased dramatically. Why?
• 10 warmest years have occurred since 1990
• 2005 warmest
• 1998 second warmest
• 2002 third warmest
• Earths temperatures may rise 1.8o 4.0o C
• (3.2o 7.2o F) by end of 21st century
• What could occur?

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Case Study Global Climate Change

• Kyoto Protocol International climate change
  conference Kyoto, Japan 1997
• Highly developed countries to cut
• CO2 emissions 5.2 by 2012
• US Department of Energy
• Automotive vehicles
• designed for better gas
• mileage
• High efficiency wind
• turbines