Home

Science Notes

Biomes

Lessons

Home

Science Notes

Biomes

Lessons

Home

The Energy Pyramid

Let's build the energy pyramid.

I go to Following the Energy Trail and find the table that shows the Primary Productivity per Square Meter per Year for my biome. I find my biome and see how many Kilocalories each square meter can produce in a year.

Level One -- Edible Calories Produced by Plants

This is where you use the number that you just found. I'm using the Polar Tundra. Summer is short, only six to ten weeks, and temperatures are below freezing for six to ten months of the year. This makes for a very short growing season. I am hoping that the plants can produce 600 Kilocalories of food per square meter. This is not even 2 KiloCalories a day, but most days the plants are paralyzed by the cold, so they are doing the best that they can.

 600 Kilocalories per Square Meter Per Year  available for herbivores to eat

Level Two -- Edible Calories Produced by Herbivores

Herbivores use about 90% of the Kilocalories that they eat for breathing, digesting, warming their bodies, running around, and reproducing. This leaves about 10% of the Kilocalories that they eat for building their bodies, which are mostly edible protein. The next level of the pyramid =

10% of 600 Kilocalories = 0.10 * 600 = 60 Kilocalories

Herbivores produce 60 Kilocalories of animal body per square meter per year
 600 Kilocalories per Square Meter Per Year  available for herbivores to eat

Level Three -- Edible Calories Produced by Carnivores Eating Herbivores

Carnivores really have to work to eat meat.

They can capture 60 Kilocalories per square meter of ground by eating the herbivores, but they can only transfor about 10% of the Kilocalories that they eat into the structures of their own bodies.

10% of 60 Kilocalories = 0.10 * 60 = 6 Kilocalories

First level predators (carnivores ) produce six Kilocalories of biomass (their actual bodies) per year per square meter.

Herbivores produce 30 Kilocalories per square meter per year
 600 Kilocalories per Square Meter Per Year  available for herbivores to eat

Make this into a graphic:

or