Ecology - Ecosystems

• Ecology


  The study of interactions between organisms with their environment
• Environment


  The surroundings of an organism
• Interactions between organisms


  May be beneficial, harmful or competitive
• Condition of the environment


  Can affect interactions and survival of species
• Interactions between organisms


  Can lead to changes in distribution and abundance, affecting biodiversity
• Levels of organisation


  • Organism
  • Population
  • Community
  • Ecosystem
  • Biome
  • Biosphere
• Organism


  An individual living thing, can be plant, animal or unicellular
• Population


  A group of organisms of the same species, living and interacting
• Community


  Different populations of organisms interacting within a specified area
• Ecosystem


  Interaction between living and non-living components within a community
• Biome


  Communities of organisms with similar characteristics due to shared physical climate
• Biosphere


  The sum of all ecosystems and biomes on the planet
• Habitat


  The local environment occupied by an organism
• Ecological niche


  The organism's role within its community, including its tolerance, habitat, adaptations, behaviour and activity patterns
• Biotic components


  • All living organisms, including plants, animals, fungi, bacteria
• Abiotic components


  • All non-living components, including chemical factors (water, oxygen, salinity, pH, ions) and physical factors (light, temperature, soil structure)
• Autotrophs


  Organisms able to convert light energy into matter, also known as producers
• Heterotrophs


  Organisms unable to produce their own energy, consume other organisms for energy, also known as consumers
• Types of consumer organisms

  • Herbivores
  • Carnivores
  • Omnivores
  • Scavengers
  • Detritivores
• Only matter can be recycled, not energy
• Recycling of matter


  1. Dead organisms consumed by scavengers and detritivores

  2. Decomposers break down organisms into simple inorganic molecules

  3. Producer organisms re-absorb these molecules
• Decomposers


  Micro-organisms, bacteria, protista and fungi that break down dead organisms
• The sun is the main source of energy for many ecosystems
• Energy flows through but is not recycled within the ecosystem, due to energy being used in respiration and lost as heat
• Flow of energy in the ecosystem

  1. Light energy used by producers to convert CO2 and water into glucose

  2. Glucose stored as starch and cellulose

  3. Producers consumed by herbivores

  4. Herbivores consumed by carnivores

  5. Omnivores consume both producers and consumers
• Food chain


  The transfer of food energy from one trophic level to another
• Food web


  Many food chains inter-linked together, summarising trophic relationships
• A large diverse food web indicates a more stable ecosystem
• Pyramid of energy


  Indicates the amount of energy produced by organisms at each trophic level
• Energy transfer along trophic levels is inefficient, with only 10% of organic matter consumed converted to organic matter for the next level
• Pyramid of biomass


  Illustrates the amount of stored energy transferred along the food chain
• For a sustainable ecosystem, the biomass pyramid must always be upright with a gradual decrease at the top
• Bioaccumulation


  The accumulation of a toxic substance in the body of an organism due to its inability to break down or metabolise the toxin
• Biomagnification


  The increase in concentration of a toxic substance as it moves up the food chain
• Toxic substances


  • DDT
  • Mercury
• Bioaccumulation and biomagnification of toxins can interfere with biological functions and cause damage, such as thinning of eggshells