1. Energy Flow In Ecology

2. How does energy flow within ecosystems?
From Trophic Level  Trophic Level
Trophic Level-each of levels in an ecosystem, made up of organisms that share the same step in the food chain
The levels of a food pyramid/chain
Means that energy flows up a food chain or through a food web

3. Trophic Levels

4. Trophic Levels
Primary Producers: The autotrophs that capture energy to make food (Plants)
Primary Consumers: heterotrophs that eat autotrophs (herbivores)
Secondary Consumers: heterotrophs that eat other heterotrophs (carnivores)
Higher Level Consumers: carnivores that eat other carnivores
Decomposers: consumers of dead organic material ( Bacteria, Fungi)

6. ENERGY FLOW Food chains: One specific energy pathway in an ecosystem
Food webs: complex energy interactions found in an ecosystem.
Many food chains interacting
Energy pyramids: representation of the total energy available to a trophic level.

9. How do I read a food web? Where to start? Always start with plants
Producers are the bottom of the energy pyramid and energy begins with them

11. FOREST FOOD WEB

12. Arctic Marine Food Web

13. Lets Practice…

14. What happens at each level?
At the producer level plants take energy from the sun and change it to produce chemical (Food) energy
PHOTOSYNTHESIS!!!!!!
The plant then stores SOME of that energy and uses some of that energy to live
The energy that is used is released as heat OR is broken down and recycled after death
The animal that eats the plant gets the plants stored energy
Then that animal stores some energy and uses some energy…..and so on up the food chain

15. So that energy… At each level the amount of energy DECREASES Why?
At the previous level a lot of the energy is lost as heat
Only 10% of the energy is transferred up each level of the food chain

16. What is a biomass pyramid?
Shows you how many organisms are at each level of the food pyramid
As you move up the amount of organisms DECREASES
Why?

17. Why? As you move up a food chain the energy DECREASES
Less energy to support larger animals
Less animals at each level

18. Biomass Pyramid

19. Energy Pyramid

21. Growth of Populations Don’t write this…
The goal of populations is to grow and get bigger. This growth however can be different depending on the circumstances

22. Growth of Populations
Exponential Growth : the maximum possible growth rate of a population

24. Do most populations achieve exponential growth?
NO!!!!
What stops them? (HINT: YOU ALREADY KNOW THE ANSWER!)
Limiting Factors

25. Limiting Factors : those environmental factors that keep a population at the carrying capacity,
like food,
predators,
amount of water
how much land there is

26. What is carrying capacity?
Carrying Capacity of the Environment: The maximum population that a particular environment can support

27. Different Growth
When a population is approaching carrying capacity and growth slows down it is referred to as LOGISTIC GROWTH

29. Population Growth over Time

30. Exponential growth can lead to massive die-off
In 1944, 20 reindeer were brought to St. Matthew Island. Initially there were abundant food sources, and the reindeer population increased dramatically.
There were no predators to cull the population. However, about 20 years later, the reindeer had overshot the food carrying  capacity of the island, and there was a sudden, massive die-off.  About 99% of the reindeer died of starvation.
Exponential growth can lead to massive die-off

31. Why did the reindeer die off?
Starvation
The environment can only support so many deer
There is only enough food to support a certain number of deer
The amount of food is the limiting factor
Then the deer die off!

32. Carrying capacity of the Environment

33. Break it down… The population begins by growing exponentially
When it reaches carrying capacity it will go over it at the beginning
Then die off will begin to happen because of limiting factors
The population will shrink back below carrying capacity
Then it will grow to slightly above carrying capacity…die off…grow…and so on

34. Let’s visualize how this looks…
Deer of the kaibob

36. Project 2 Create your own-
Using clip art/magazines/drawings create one food chain. Then incorporate that food chain into a food web. On the back identify each organism in your web and label them as
Producer
Primary Consumer
Secondary Consumer
Decomposer
Remember! Each Food Web/Chain MUST have at least one of EACH producer, consumer and decomposer