Ecosystems

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Ecosystems

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Realm of Ecology
Biosphere
Ecosystem
Communities
Populations
Organisms
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Realm of Ecology

• Species
• All organisms of the same kind that are
  genetically similar enough to breed in nature and
  produce live, fertile offspring
• Population
• All the members of a species living in an area at
  the same time

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Realm of Ecology, cont.

• Community
• All of the populations of organisms living and
  interacting in a particular area
• Ecosystem
• Composed of a biological community and its
  physical environment

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Ecosystems

• Ecosystem
• A community of different species interacting with
  one another and with their nonliving environment
• Can be small or large, e.g. a stream or Great
  Plains
• Can be natural or artificial, e.g. cropfields
• All of the Earths ecosystems together make up
  the biosphere

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Biodiversity

• The forms of life that can best survive the
  variety of conditions currently found on earth
• Types of Biodiversity
• Genetic Diversity
• Species Diversity
• Ecological Diversity

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Components of Ecosystems

• Biotic (living components)
• Producers make their own food from compounds
  obtained from their environment
• Photosynthesis capturing sunlight to make
  sugars
• 6CO2 6H2O sun ? C6H12O6 6O2
• Consumers get their energy and nutrients by
  feeding on other organisms
• Aerobic respiration uses oxygen to convert
  organic nutrients into carbon dioxide and water
• C6H12O6 6O2 ? 6CO2 6H20 energy

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Types of Consumers

• Herbivores
• Plant eaters
• Primary consumers
• Feed directly on producers
• Carnivores
• Meat eaters
• Feed on other consumers
• Secondary and tertiary consumers

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Types of Consumers, cont.

• Omnivores
• Eat both plants and animals
• Scavenger
• Feed on dead organisms
• Decomposers
• Bacteria and fungi
• Complete the final breakdown and recycling of
  organic materials

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Components of Ecosystem

• Biotic (living components)
• Abiotic (nonliving components)
• Sunlight
• Temperature
• Precipitation
• wind

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Major components of an ecosystem in a field
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Major components of a freshwater pond ecosystem
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How does energy flow through ecosystems?

• Food chain
• The sequence of organisms, each of which is a
  source of food for the next
• Energy enters most ecosystems as high quality
  sunlight, which is converted to nutrients by
  producers. The energy is then passes on to
  consumers.
• As each organism uses the high-quality energy in
  its food to move, this energy is converted into
  low-quality heat (2nd law of thermodynamics)

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Model of a Food Chain
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Food Chain

• Trophic Level
• All organisms that are the same number of energy
  transfers away from the original source of energy
  that enters an ecosystem
• Producers 1st trophic level
• Primary consumers 2nd trophic level
• Secondary consumers 3rd trophic level
• But real ecosystems are more complex than this

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Food Web

• Most consumers feed on more than one type of
  organism
• Food web complex network of many interconnected
  food chains

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Food Web
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Energy Transfer in a Food Web

• In a food chain or web, energy is transferred
  from one trophic level to another, with some
  usable energy degraded and lost to the
  environment as heat.
• At each successive trophic level, some of the
  available biomass isnt digested and expelled as
  waste
• Only a small portion of what is eaten is
  converted into an organisms biomass, and the
  amount of usable energy available to each
  successive trophic level declines (80-90 is lost)

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Biomass Transfer
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Pyramid of Energy Flow

• A diagram representing the flow of energy through
  each trophic level in a food chain or web
• With each energy transfer, only a small part
  (typically 10) of the usable energy entering one
  trophic level is transferred to the organisms at
  the next trophic level

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Generalized pyramid of energy flow
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Energy Pyramid
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Energy Pyramid for Grassland