1. NOTES 34 – Energy Flow Through the Ecosystem

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

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

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

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

6. Food Web

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

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

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

10. Biomass Reduction

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

12. Eating Meat vs. Eating Plants
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

13. Energy/Matter Flow Through Ecosystem

21. 1st trophic level - (autotrophs) grasses, trees, algae
2nd trophic level – (herbivores) small fish, some insects, cows, squirrels, deer
3rd trophic level and above – (carnivores/omnivores) bears, humans, hawks, sharks, dolphins, lions, some insects

22. Energy Flow Through Ecosystem