numbers of organisms biomass of organisms energy stored in organisms productivity of organisms Pyramid

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					Pyramids

 Numbers, Biomass, & Productivity
FOOD CHAINS AND
PYRAMIDS
   Pyramid diagrams give information
    about the organisms in a food chain:
       numbers of organisms
       biomass of organisms
       energy stored in organisms
       productivity of organisms
Pyramid diagrams
   are drawn to scale
   the width of each rectangle is
    proportional to:
       the number of organisms per square
        meter
       or the biomass in grams per square meter
       or the productivity in joules per square
        meter per month/year
    Pyramid of Numbers
   The information collected for each trophic level
    is the total number of organisms in the area,
    which depends on:
       the size of individual organisms
       the standing crop at the trophic level
   Problem is each organism is counted equally.
       1000 kg tree = 1 gram grass plant
   Units = organisms
   Number pyramid diagrams may be:
       upright pyramids
       inverted pyramids
Pyramid of Biomass
   Takes the total biomass of all organisms at
    each trophic level in the area , and depends
    on:
       the energy available at each trophic level
       the standing crop at each trophic level
   Problem it is a measure in one instant of time
   Unit = grams
   Biomass pyramid diagrams may be:
       upright pyramids
       inverted pyramids
Pyramid of Productivity
   These show productivity of organisms at
    different trophic levels, which depends on:
       the energy available from the previous trophic
        level
       the efficiency of the organisms
   Unit = joules
   Designed to eliminate the inverted pyramid

				
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posted:11/6/2012
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