Ecosystems

4.1 - What is an Ecosystem?
Ecology is the study of the environment.

Biotic factors are all of the things in the environment that are living or were living at one time.  This includes plants, animals, fungi, bacteria, etc.

Abiotic factors are all of the things in the environment that are not living, and never were alive.  This includes air, water, light, heat, rock/sand, etc.

Levels  of  Organization
   Organism - One complete living thing.
   Population - All of the members of one species in an area.
   Community - All of the living things that interact within an area.
   Ecosystem - The community of organisms in an area and their
       physical environment.  (All biotic and abiotic factors.)
   Biome - A large area with a specific climate and certain types of
       communities that live there.
   Biosphere - The part of the Earth that supports life.

Habitat is the place where an organism lives.

Biodiversity is the variety of organisms (or species) in an area.

Succession is the replacement of one type of community with another in a certain location over a period of time.

Biomes
A biome is a large area with a specific climate and certain types of communities that live there.

Climate is the average weather in an area over a long period of time.  The two key climate factors that determine what biomes can exist in an area are temperature and precipitation.

Three Major Groups of Terrestrial Biomes
1. Tropical - warm, near the equator
   a. Tropical Rain Forests
      - receive a large amount of rain
   b. Savannas (Tropical Grasslands)
      - have long, dry seaons and short, wet seasons
   c. Tropical Deserts
      - receive very little rain
2. Temperate - mid-latitudes, wide range of temp. over the year
   a. Temperate Forests
      - mild climates with plenty of rain
         - deciduous (broadleaf trees that lose leaves in autumn)
         - coniferous (cone-bearing trees that don't lose needles)
         - mixed forest (both types of trees)
   b. Temperate Grasslands
      - have moderate precipitation, cooler temps than savannas
   c. Temperate Deserts
      - very little precipitation, wide temp. ranges
3. High-Latitude (Polar) - cold
   a. Taiga
      - coniferous forests in cold, wet areas
      - long, cold winters - most precipitation falls in summer
   b. Tundra
      - little precipitation
      - permafrost
      - only short plants with shallow roots survive there

Four Major Groups of Aquatic Ecosystems
1. Freshwater Ecosystems
   - bodies of fresh water (lakes, ponds, rivers, etc.)
2. Wetlands
   - link between land and fully aquatic habitats
   - dominated by water-loving plants
   - wetlands control flooding and filter water
3. Estuaries
   - places where fresh and salt water mix (rivers meet ocean)
4. Marine Ecosystems 
   - ocean habitats

4.2 - Energy Flow in Ecosystems

Trophic Levels are the steps in a food chain or energy pyramid.  each trophic level is a step in the transfer of energy through an ecosystem.

Trophic Level "Roles"
1. Producers are organisms that produce their own food inside
    their bodies.  Plants are producers because they use sunlight to
    make sugar in their leaves by photosynthesis.
2. Consumers are orgsnisms that must take in food.  Animals are
    consumers because they must eat food to survive.
    a. Herbivores are consumers that only eat plants.
    b. Carnivores are consumers that only eat animals.
    c. Omnivores are consumers that eat both plants and animals.
3. Decomposers are organisms that break down dead material
    and return it to the soil.

Food Chain - A diagram that shows one set of relationships in an
  ecosystem.
Food Web - A diagram that shows many sets of relationships in
  an ecosystem.
Energy Pyramid - A triangular diagram that shows an
  ecosystem's energy loss as energy is passed up the food chain.

The Ten Percent Rule
  - Only 10% of the energy that a consumer takes in becomes part
     of the consumer's body.
  - The other 90% is used by the consumer.
  - Only the 10% that is stored can be passed on to a higher-level
     consumer.

4.3 - Cycling of Matter  

The Water Cycle
The Water Cycle is the process by which the Earth purifies and recycles its water.  There are seven main parts to the Water Cycle:

1. Evaporation happens when water changes from a liquid to a gas.
2. Condensation happens when water changes from a gas to a liquid.
3. Precipitation is the name for water falling from the sky.
4. Run-Off is water flowing along the surface of the ground.
5. Percolation happens when water soaks into the ground.
6. Groundwater is water in the ground.
7. Transpiration is evaporation caused by plants.

The Carbon Cycle
Carbon is cycled back and forth between living things and their nonliving environment.
1. Photosynthesis is carried out by plants and changes CO2
    (carbon dioxide) into O2 (oxygen).
2. Respiration is carried out by animals, plants, and other
    organisms and changes O2 into CO2.
3. Combustion is the burning of a substance; it changes O2
    into CO2.
4. Decomposition is the breaking down of dead matter; it
    changes O2 into CO2.

The Nitrogen Cycle
Nitrogen is important in making proteins.  The nitrogen in the air (N2) is not accessible to most organisms, and must be changed to another form.
1. Nitrogen Fixation is the process by which bacteria combine
    N2 with hydrogen (H2) to make ammonia (NH3).  N2 can also
    be fixed into NH3 by lightning and burning fossil fuels.
2. Ammonification is the process by which nitrogen in animal
    waste or dead matter is converted into NH3.
3. Nitrification is the process by which NH3 is converted into
    nitrate (NO3).
4. Assimilation is the process where plants absorb NH3 and
    NO3 from the soil.  (The nitrogen can then be passed up the
    food chain.)
5. Denitrification is when NO3 is changed back into N2 and
    released into the atmosphere.

The Phosphorous Cycle
Phosphorus is important in making DNA and ATP (an energy molecule).
a. Phosphorous is found in the soil as calcium phosphate
    (CaPO4).  CaPO4 also makes up 70% of bone tissue.
b. CaPO4 dissolves in water to form phosphate.
c. Plants absorb phosphate through their roots.  (The phosphorous
    can then be passed up the food chain.
d. When organisms die, phosphorous is returned to the soil.

Subpages (1): Files for Ecosystems