Ecosystem Balance and Processes

Ecosystem Processes

• Four processes necessary to keep an ecosystem self-supporting and balanced:
  • Energy Production: Autotrophs and producers convert solar energy into usable chemical energy
  • Energy Transfer: Energy from plants transfers to herbivores and carnivores that eat them
  • Decomposition: Scavengers and detritivores consume dead abiotic materials, breaking them down with microorganisms and fungi
  • Recycling: Elements and compounds are reused in the environment, never added or lost, just reused

Levels of Organization of Ecology

• Six levels of organization of ecology:
  • Biosphere: All living and non-living things on Earth
  • Biome: Ecosystem covering wide areas with similar climate and organisms
  • Ecosystem: Community living together in a similar habitat
  • Community: All populations living in an area
  • Population: Members of the same species living together
  • Organism: Any single living thing

Biomagnification

• Four conditions required for biomagnification:
  • Pollutants must be long-lived, concentrated by producers, fat-soluble, and biologically active

Population Characteristics

• Three characteristics of populations:
  • Population Density: Number of individuals in relation to space occupied
  • Spatial Distribution: Spacing pattern of a population in an area
  • Growth Rate: How fast a population grows

Symbiotic Relationships

• Three symbiotic relationships:
  • Parasitism: One organism benefits, the other is harmed
  • Mutualism: Both species benefit
  • Commensalism: One species benefits, the other is neither harmed nor helped

Biodiversity and Ecosystem Health

• Biodiversity affects ecosystem health through:
  • The "Domino Effect": Loss of a single species can cause a chain reaction in the food web
  • Ecosystem Services: Species work together to maintain oxygen levels, remove carbon dioxide, cycle nutrients, and purify water

Species at Risk

• Reasons why species are at risk:
  • Habitat Loss: Removal of habitat due to agriculture, urbanization, roads, and pipelines
  • Over-Exploitation: Excessive hunting, fishing, or trapping
  • Pollution: Harmful materials in the environment, toxic chemicals in water
  • Invasive Species: Alien species outcompeting native species

Population Change Formula

• Population change formula: population change = births - deaths + immigration - emigration
• Example: Regina population change in 2008

Ultimate Source of Energy

• The ultimate source of energy is solar energy

Energy Flow and Trophic Levels

• Energy flows through an ecosystem, while matter cycles
• Trophic levels:
  • Rabbit: Secondary consumer
  • Fox: Tertiary consumer

Nutrient Cycles

• Three stages of a nutrient cycle:
  • Input: Nutrients enter an organism (e.g., barn owl breathes or eats living organisms)
  • Throughput: Nutrients are used by organisms for growth and function (e.g., digestion breaks down food)
  • Output: Waste matter, used, and unneeded nutrients are returned to the environment (e.g., decomposition)

Carbon and Nitrogen Cycles

• Carbon cycle:
  • Steps: Photosynthesis, Respiration, Decomposition, Combustion
• Nitrogen cycle:
  • Steps: Nitrogen Fixation, Ammonification, Nitrification, Denitrification

Energy and Matter

• Energy flows through an ecosystem, while matter cycles
• Short-term and long-term carbon stores:
  • Short-term: Living things, atmosphere, plants, rotting tissues
  • Long-term: Underground coal, natural gas, sedimentary rocks, ocean floor