2'1 Energy Flow in Ecosystems

1
2.1 Energy Flow in Ecosystems

• Biomass total mass of all living things in a
  given area.
• Can also refer to mass of a particular type of
  matter (e.g. organic materials used to produce
  biofuels)
• Measured in g/m2 or kg/m2 .
• Within an organisms niche, organism interacts
  with the ecosystem by
• Obtaining food from the ecosystem
• Contributing energy to the ecosystem
• Producers plants (produce carbohydrates from
  CO2,
• H2O, and Suns energy).
• Consumers get energy by feeding on producers or
• other consumers.
• Decomposition breakdown of wastes and dead
  organisms by organisms called decomposers
  through biodegradation.

Bees are consumers.
See pages 56 - 59
2
Energy Flow and Energy Loss in EcosystemsFood
Chains

• Different methods to show energy moving through
  ecosystems.
• Food chains
• Food webs
• Food pyramids
• Food chains show the flow of
• energy in an ecosystem.
• Each step in a food chain is a trophic level
• Producers 1st trophic level
• Primary consumers 2nd trophic level
• Secondary consumers 3rd level
• Tertiary consumers 4th level

See pages 59 - 60
3
Energy Flow and Energy Loss in EcosystemsFood
Chains (continued)

• Consumers in a food chain
• Detrivores consumers obtain energy and
  nutrients from dead organisms and waste matter
• E.g. earthworms, bacteria and fungi.
• Feed at every trophic level.
• have own, separate food chains
• and are very numerous.
• Herbivores primary consumers
• Eat plants (producers) only.
• Carnivores secondary or tertiary consumers
• Secondary consumers eat non-producers
  (herbivores).
• Tertiary consumers eat secondary consumers.
• Also called top consumers or top carnivores.
• Omnivores consumers that eat both plants and
  animals
• E.g. humans and bears.

This dung beetle is a detrivore.
See page 61
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Energy Flow and Energy Loss in EcosystemsFood
Webs

• Food webs interconnected food chains
• Most organisms are part of many food chains.
• Are models of the feeding relationships in an
  ecosystem.
• Arrows represent flow of energy and nutrients.
• Following arrows leads to the top carnivore(s).

This food web represents a terrestrial ecosystem
that could be found in British Columbia.
See page 62
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Energy Flow and Energy Loss in EcosystemsFood
Pyramids

• Food pyramids show changes in available energy
  from one trophic level to another in food chain.
• Energy enters first trophic level (producers)
  large amount of biomass and energy.
• Many organisms in one trophic level to meet the
  energy needs of next trophic level.
• Loss of energy at each level.
• 80 90 of energy used in chemical reactions
• in body lost as thermal energy.
• Little energy left over for growth or increase
  in biomass.

Ninety percent of this mouses food energy is
used to maintain its life functions.
See page 63
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Energy Flow and Energy Loss in EcosystemsFood
Pyramids (continued)

• Food pyramids ecological pyramids.
• May show biomass, population, or energy numbers.
• Amount of life an ecosystem can contain is based
  on the bottom level of the ecological pyramid,
  where producers capture energy from the Sun.
• Each level in the energy pyramid a loss of 90
  of total energy available.
• Lower trophic levels larger populations.
• Shows importance of
• maintaining large, biodiverse
• populations at the lowest levels
• of the food pyramid.

See pages 63 - 64
Take the Section 2.1 Quiz