The Biosphere.

What is ECOLOGY  1866 German Biologist Ernst Haeckel first coined the term ecology.  Came from the Greek word oikos meaning “house”  Defined today as the study of interactions among living organisms and their environment

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Energy Flow  The sun is the main source of energy for life on earth.  < 1 % of all sunlight that reaches earth is used by living organisms.  What happens to the rest?

 Most is reflected off as heat energy.

Producers or Autotrophs UUse sunlight or chemicals to make their own food. EExamples:

. 66CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 PPerformed on land by plants and in water by algae.

Can organisms make their own food without the aid of sunlight?  Chemosynthesis: using chemical energy to make carbohydrates.  Usually performed bacteria found in harsh environments –Ocean vents, volcanoes, hot-acidic

Consumers or heterotrophs  Herbivores  Carnivores  Omnivores  Detritivores  Decomposers HHerbivores CCarnivores OOmnivores DDetritivores DDecomposers

Food Chains

Food Webs  More complex than food chains  A complex net of interactions among organisms. (interdependence)

Trophic Levels  Each location or step in a food chain or food web represents a trophic level.  Examples: producers, primary consumers, secondary consumers, etc.

Ecological pyramids  Only about ten percent of the energy available within a trophic level is transferred to oragnisms at the next higher level.

Other pyramids: BBiomass and numbers

Cycles of matter  Unlike energy, matter is constantly being recycled in an ecosystem.  Known as biogeochemical cycles

Transpiration  The release of water from the leaves of plants.  Water is exchanged through a plant’s stomata.  Evaporation is the second process that releases water into the atmosphere.

Carbon Cycle 1. Biological processes (photosynthesis, respiration, decomposition) 2. Geochemical processes (volcanoes) 3. Biogeochemical (fossil fuels) 4. Human activity (factories, deforestation, car exhaust)

Nitrogen Cycle  All organisms need nitrogen to live.  Most abundant gas in atmosphere (80%)  Nitrogen gas is unusable for plants  Must be “fixed” or changed into the nitrate or nitrite form by bacteria in the soil. Known as nitrogen fixation

Phosphorus cycle PP is important in the production of DNA and RNA. UUnlike water,oxygen, and nitrogen, phosphorus is NOT found in the atmosphere. Found in rocks and minerals.

Nutrient Limitation  When a single nutrient is scarce for a particular ecosystem and limits the growth of organisms in that ecosystem.