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 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