Biomass of a 1 acre Oat field

1
Biomass of a 1 acreOat field
2
Background

• Grains are edible energy stores of starch a plant
  makes using photosynthesis
• Grains ARE the 10 of energy available to the
  next trophic level
• Plants can only use approx. 1.2 of available
  energy from the sun!
• 1 acre approx. size of a football field

3
Ecosystem

• Farmland 1 acre with oat grain crops
• Grasshoppers population in oat fields
• River on edge of farm
• Frog population on riverbank
• Stocked with trout
• Human farmers hoping to use trout as personal
  food source

4
Food Chain
?
?
?
?
5
Example Calculation!

• How many frogs are supported by 100 grasshoppers?
• Given
• Frog needs 1,300 calories a year to survive
• 1 grasshopper 35 g of biomass
• Each gram of biomass has 3.08 calories
• Calculate 35g biomass x 3.08 calories/g
  107.8calories in 1 hopper
• 100 hoppers x 107.8 10,780 calories in the
  second trophic level (grasshoppers) available to
  the frogs
• Divide calories (energy) at second trophic
  level by NEEDS of third trophic level (frog)
• 10,780 calories in hoppers/1,300 calories needed
  by frogs 8.29 Frogs supported by grasshoppers