Ecology

• Ecology


  The study of how organisms interact in an ecosystem
• Organisms


  • Generally compete for food, water, space, CO2, light, shelter, mates
• Interdependence


  The fact that organisms can rely on each other for resources and form a community
• Abiotic factors in an ecosystem

  • Light
  • Temperature
  • Moisture
  • Soil pH
  • CO2 levels
  • O2 levels
• Biotic factors in an ecosystem

  • Food availability
  • Predators
  • Prey
  • Pathogens
  • Breeding behavior
• Using quadrats to estimate population size

  1. Sample around 10% of the area

  2. Take a mean

  3. Multiply up for the whole area
• Food chain


  The direction that biomass and energy flows in an ecosystem from one organism to another
• Trophic levels


  • Producers
  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
  • Apex predators
• All life is carbon-based, so when organisms die the carbon is recycled and can be used to make more organisms</b>
• Water follows a cycle of rain, rivers, sea, evaporation, repeat
• Decomposition


  Used by farmers to produce natural fertilizers and methane gas
• Biodiversity


  The number of different types of organisms in an ecosystem
• High biodiversity generally makes for a stable ecosystem
• Human development usually results in lower biodiversity
• Carbon dioxide and methane contribute to global warming, but water vapor is responsible for 95% of the greenhouse effect
• Deforestation reduces biodiversity and is often done to create farmland
• Pyramid of biomass


  Shows the relative mass entering each trophic level in a food chain
• Biomass is lost at each trophic level due to organisms living and not being fully consumed
• Food security


  The availability of food and one's access to it
• Factors affecting food security include increasing population, changing diets, transportation, farming costs, and conflicts
• Sustainable fishing


  1. Use nets with holes to catch adult fish but let juveniles through

  2. Allows young fish to breed and maintain populations