Food Chains and Biomass Pyramids on Rangelands USDA-ARSJ. Peterson

Trophic Levels  Feeding levels with respect to primary source of energy  Producers & consumers each occupy a different trophic level  Energy is lost at each level

Trophic Levels and grasslands

Biomass Pyramid  The total weight of all living organisms  Biomass at each trophic level  biomass pyramid Biomass pyramid (grams/m 2 ) Producers Herbivores Primary carnivores Top carnivores Detrivores/ decomposers 5

Trophic Levels 1 st Trophic Level Producers Plants 2 nd Trophic Level Primary Consumers Herbivores 3 rd Trophic Level Secondary Consumers Carnivores Decomposer

Biomass Pyramids 1 st Trophic Level Producers Plants 2 nd Trophic Level Herbivores 3 rd Trophic Level Carnivores Decomposer

Biomass Pyramids 1 st Trophic Level Producers Plants 2 nd Trophic Level Herbivores 3 rd Trophic Level Carnivores Decomposer

Biomass Pyramids Decomposer At each level some biomass is not passed to next higher level

Biomass decreases at higher trophic levels Not all biomass is passed from one trophic level to next  Not all is consumed  Not all that is consumed is digestible  Not all that is digested is turned into mass  Part of mass is converted to energy or heat  Lost mass is available for decomposition

Vegetarian Solution? Shorter food chain/web = less loss of energy Vegetarianism results in a decrease of human position on food chain. Is vegetarianism is the best way to feed a large population? Will this solve the world food problem?

1) Cellulose  most abundant, naturally occurring organic molecule on earth  Humans can’t digest cellulose,  Ruminants & Hind-gut fermentors can.  We need cows, sheep, goats, horses, llamas, alpacas, etc. to digest cellulose for us. 2) Only about 10% of the earth land surface can be farmed.  The rest is too rocky, too cold, or too dry.  We need animals to harvest these land for us. Two Good Reasons Drawing by Mike Hale