Energy and Matter in Ecosystems

• Matter


  Anything that takes up space and has mass, consists of atoms
• Matter RECYCLES through ecosystems in organic and inorganic forms
• Energy


  The capacity to cause change, particularly to do work. It can exist in a variety of forms, such as heat, light and chemical, and can be transformed from one form to another
• ENERGY CAN NOT BE RECYCLED
• Ecosystems require a constant supply of energy that originates primarily from the Sun
• Energy can be transferred or transformed
• The Sun


  Provides energy to Earth as heat and light, major source of energy that drives diverse ecosystems
• Biotic components of an ecosystem

  • Decomposers
• Biomass


  Total mass of biological matter (living or dead) in a given area, at the time of measurement, that can be used as an energy source
• Productivity


  Percentage of energy entering an ecosystem that is incorporated into biomass
• Primary productivity


  Percentage of energy that is incorporated into biomass by primary producers
• Net primary productivity (NPP)

  Gross production - energy lost in respiration
• NPP can be calculated using the equation: Net production = gross production - energy lost in respiration
• Different ecosystems have different primary productivity rates
• Food chains


  Examples of qualitative, predictive models that allow ecologists to monitor the sustainability of feeding relationships in an ecosystem
• Trophic level


  Position an organism has in a food chain
• The 10% rule in ecology states that, on average, only about 10% of the energy at one trophic level is passed on to the next level. The remaining 90% is lost to the surroundings as heat energy and chemical energy in wastes.
• Trophic efficiency


  How much energy is available from one level to the next within a food chain. An estimate of the average amount available to successive levels is 10%
• Food webs are integrated food chains
• Ecological pyramids


  Diagrams that illustrate the relative levels of one of three different factors present at each trophic level in an ecosystem
• Types of ecological pyramids

  • Pyramids of numbers
  • Pyramids of biomass
  • Pyramids of energy
• Drawing pyramids of energy


  Bottom level should represent a producer

  2. Subsequent levels should be labelled primary, secondary and tertiary consumer

  3. Each trophic level should be drawn to scale, one-tenth the length of the preceding level

  4. Use labelled arrows to indicate energy leaving each trophic level as heat
• Biogeochemical cycle


  Model describing how chemical elements or molecules are transformed and stored in biological and geological components of Earth's biosphere
• Carbon cycle


  Biogeochemical cycle by which carbon is exchanged between biosphere, geosphere, hydrosphere and atmosphere
• Detritivores


  Organisms that feed on plant detritus
• Decomposers


  Organisms that break down complex organic matter into simple inorganic molecules (nutrients)
• Nitrogen cycle


  Biogeochemical cycle that depends on metabolic activities of nitrogen-fixing, nitrifying and denitrifying bacteria
• Nitrogen fixers


  Specialised bacteria that invade root hairs of plants like legumes, forming nodules in a symbiotic relationship
• Ecological niche


  The role a species has in its ecosystem and the conditions it requires to persist
• Competitive exclusion principle


  No two species can occupy the same niche in the same environment for an extended period of time
• Keystone species


  Not necessarily abundant, but can exert a disproportionately large effect on population numbers of other species in the community
• Atoms


  The buildings blocks of matter

  Enters and exists an ecosystem
• Forms of energy


  Heat

  Chemical

  Light

  Electrical
• Energy and matter interact in ecosystems


  The energy from sunlight is transformed into chemical energy in biomass
• Energy can be transformed and transferred 


  Transformed: From one type of energy to another. Eg. light energy can be transformed into chemical energy and stored in producers.

  Transferred: Energy can be moved from one organism to another. Eg. from producer to consumer by consumption of food. The energy type stays the same
• The Sun


  Is the ultimate source of energy involved in food webs. The Sun provides energy to Earth as heat and light. It is the major source of energy that drives the diverse ecosystems on Earth.
• Biotic components of an ecostem

  Producer -> primary consumer/herbivores -> secondary consumers ->tertiary consumers -> top carnivore/apex predator -> decomposer then all over again

  
• Light energy


  Enters ecosystem via autotrophic producers who transform light energy into chemical food energy during photosynthesis.
• Chemical energy


  Energy stored in chemical bonds in the carbohydrate food is transferred to consumers upon consumption.
• Heterotrophs depend on autotrophs 


  Members of a community consume food because they can not perform the process of photosynthesis are called heterotrophs.