Post on 04-Jan-2016
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