NOTES 34 Energy Flow Through the Ecosystem Energy

NOTES 34 – Energy Flow Through the Ecosystem

Energy Pathways n n What is the source of all the energy in this picture? What path does this energy take to get to the hawk?

How does energy move through and ecosystem from one organism to another? Food Chain – a model that ecologists use to show energy moves from one organism to another in an ecosystem Ex. Berry Plant → Cricket → Field Mouse → Snake → Hawk

Trophic Level – a link in the food chain (feeding level)

Food Web – a model showing all the possible feeding relationships in an ecosystem

Food Web

Pyramid of Numbers n The number of organisms decreases as you go up the food chain – why?

Which number is greater? The mass of all the crops grown to feed humans or the mass of all the humans? n n n All humans ~ 100 million metric tons (100, 000 X 2, 204 lbs = 220, 400, 000 lbs) All crops ~ 2, 000 million metric tons All organisms ~ 2, 000 billion metric tons (1, 600 billion tons in forests)

Pyramid of Biomass n The total mass of organisms decreases as you go up the food chain – why?

Biomass Reduction

Pyramid of Energy n The amount of available energy decreases as you go up the food chain

Eating Meat vs. Eating Plants n n The lower you eat on the food chain, the more energy available You can feed more people on an equivalent amount of plant by eating the plant directly than by feeding it to an animal then eating the animal

Energy/Matter Flow Through Ecosystem

1 st trophic level - (autotrophs) grasses, trees, algae 2 nd trophic level – (herbivores) small fish, some insects, cows, squirrels, deer 3 rd trophic level and above – (carnivores/omnivores) bears, humans, hawks, sharks, dolphins, lions, some insects

Energy Flow Through Ecosystem