ECOSYSTEM ECOLOGY

• Ecosystem


  A community interacting with the physical environment
• Components of an ecosystem

  • Abiotic components
  • Biotic components
• Abiotic components


  Resources, such as sunlight and inorganic nutrients, and conditions, such as type of soil, water availability
• Biotic components of an ecosystem

  Influenced by the abiotic components, as when the force of the wind has affected the growth of a tree
• Biotic components of an ecosystem

  • Autotrophs
  • Heterotrophs
• Autotrophs


  Require only inorganic nutrients and an energy source to produce organic nutrients for their own use and for all the other members of a community. They are also called producers because they produce food.
• Photoautotrophs


  Also called photosynthetic organisms, produce most of the organic nutrients for the biosphere
• Heterotrophs


  Need a preformed source of organic nutrients. They are also called consumers because they consume food.
• Types of heterotrophs


  • Herbivores
  • Carnivores
  • Scavengers
  • Detritivores
• Herbivores


  Animals that graze directly on plants or algae
• Carnivores


  Feed on other animals
• Scavengers


  Feed on the dead remains of animals and plants that have recently begun to decompose
• Detritivores


  Feed on detritus (organic remains in the water and soil that are in the final stages of decomposition)
• Decomposers


  Bacteria and fungi, including mushrooms that use their digestive secretions to chemically break down dead organic matter
• Food web


  A diagram that describes trophic (feeding) relationships; an interconnected food chains
• Trophic level


  Composed of organisms that occupy the same position within a food web or chain
• Food chain


  Movement of energy and nutrients from one trophic level to the next
• Food web


  Network of interconnected food chains
• Types of food webs

  • Connectedness food web
  • Energy flow food web
  • Functional food web
• In a food web, connectance decreases with increasing number of species
• In a food web, some species have disproportionately large effects
• Keystone species


  Species within a community that has a significant role out of proportion to its abundance
• Indicator species


  Species whose status provides information on the overall health of a food web or ecosystem
• Umbrella species


  Species whose habitat requirements are so large that protecting them would protect many other species existing in the same habitat
• Flagship species


  Single large or instantly recognizable species
• Ecosystem engineers


  Species that create, modify and maintain habitats
• Examples of ecosystem engineers

  • Green plants
  • Soil organisms
  • Beaver
  • Corals
  • Trees
  • Gopher tortoise
  • Woodpecker
  • Termite
  • Vertebrates
• Ecological pyramid


  Graphic representation of the number of organisms, the biomass, or the relative energy content of the various trophic levels in an ecosystem

  
• Ecological pyramids are helpful for explaining energy loss in an ecosystem, but they oversimplify energy flow
• Biomass decreases at each higher trophic level due to heat loss
• Types of ecological pyramids

  • Pyramids of energy
  • Pyramids of biomass
  • Pyramids of numbers

  
• Primary production


  Amount of solar energy converted by producers to chemical energy in biomass
• Net primary production


  Amount of biomass produced minus amount used by producers in cellular respiration
• Ecological efficiency


  Percentage of useable energy transferred as biomass from one trophic level to the next
• Factors of ecological efficiency

  • Consumption efficiency
  • Assimilation efficiency
  • Production efficiency
• Biogeochemical cycles


  Elements pass from one organism to another and among parts of the biosphere through closed loops powered by the flow of energy

  
• Components of biogeochemical cycles

  • Biological processes
  • Geological processes
  • Chemical and physical processes
• Reservoir


  Source normally unavailable to producers, such as the carbon present in calcium carbonate shells on ocean bottoms
• Exchange pool


  Source from which organisms do generally take chemicals, such as the atmosphere or soil
• Major biogeochemical cycles


  • Phosphorus cycle
  • Carbon cycle
  • Nitrogen cycle
  • Sulfur cycle
  • Hydrologic cycle