ENERGY FLOW IN ECOSYSTEM n How does energy

ENERGY FLOW IN ECOSYSTEM n. How does energy flow in an ecosystem? n. What is an energy pyramid? n. What is a trophic level?

ENERGY ENTERS ECOSYTEM n All energy in ecosystem comes from the sun n First law of Thermodynamics: Energy cannot be created or destroyed (but it can be transformed into stored energy & heat)

ENERGY LEAVES ECOSYSTEM n Second law of thermodynamics: Energy is lost as energy is transformed n In ecosystem, when energy is transformed, some energy is lost as HEAT

Only about 10% of the energy consumed by a first-level consumer is available for the second-level consumer. n The other 90% is used to support the life processes (keeping warm, pooping, etc) of the consumer n This means that the higher the level of consumer, the fewer there are of them because they have to eat A LOT to get enough energy n

ENERGY PATHS 3 ways to illustrate energy flow 2. Food Web: many paths 1. Food Chain: Single path 3. Food Pyramid

FOOD CHAINS n A food chain shows the path of energy from one organism to the next n energy flows from producers to consumers n arrows point to who is eating (plant is eaten by herbivore) n Usually decomposers are left out

FOOD WEBS n A food web shows all feeding relationships in an ecosystem (made of many food chains)

FOOD WEBS n Typically, food webs go like this: CONSUMER (OMNIVORE) CONSUMER (CARNIVORE) remember: decomposers receive energy from all other organisms in an ecosystem CONSUMER (HERBIVORE) DECOMPOSER PRODUCER

Types of Consumers 1. Herbivores – organisms that eat only plants (producers) • Example: cattle 2. Carnivores – organisms that eat only animals • Example: coyotes 3. Omnivores – organisms that eat both plants and animals • Example: bears, people

FOOD CHAINS AND WEBS n Practice! Draw a food chain that includes the following organisms: grasshopper n mouse n grass n owl n n Now label the organisms as producers, consumers (which type? ), or decomposers Tertiary CONSUMER (OMNIVORE) Secondary CONSUMER (OMNIVORE) Primary CONSUMER (HERBIVORE) PRODUCER

FOOD CHAINS/WEBS & ENERGY PYRAMIDS n Food chains/webs can be written as a pyramid: n Producers form the base of the pyramid n Consumers form the upper layers

What is an energy pyramid n An energy pyramid is a graphical model of energy flow in a community. The different levels represent different groups of organisms that might compose a food chain. From the bottom-up, they are as follows:

n Producers (autotrophs)— brings energy from nonliving sources into the community-makes own food n Primary consumers (heterotrophs)— eat the producers, which makes them herbivores in most communities-obtains food and energy by eating other organisms

n Secondary consumers (heterotrophs) — eat the primary consumers, which makes them carnivores and sometimes omnivores n Tertiary consumers (heterotrophs) — eat the secondary consumers

Which is both a first and second level consumer?

Energy Pyramid Tertiary Consumer Secondary Consumer Primary Consumer Producer

ENERGY PYRAMIDS The energy pyramid shows energy flow in an ecosystem: n n A level of the energy pyramid is called a TROPHIC LEVEL Each trophic level represents the energy for those organisms Top Consumer Energy stored by Secondary Consumers Energy stored by Primary Consumers ENERGY STORED BY PRODUCERS

TROPHIC LEVELS n Energy is lost with each trophic ~90% is released to the environment as heat by the organism n ~10% of the energy is used for the next level n Only about 10% of the energy from one level is passed on to the next level

What is a community? Communities are populations of organisms that interact with each other. n The interactions among different populations are what hold a community together. n A good example is a tree that houses birds, insects, and other creatures. n

Population includes all the members of a species found in a given area. n Your lawn has populations of dandelions, grasses, earthworms, and other living things. These populations together make up a lawn community. Lawn n Community earthworms dandelions grasses populations

THINK!!!! n Brainstorm jobs that people have in the community. n Discuss with your group how those jobs are important to the health of the community. n What would stop them from doing their jobs?

Niche n the role played by an organism in the natural world. n the way a species relates to, or fits in with, its environment. n Animals and plants all have very special roles to play in their communities. The niches they fill help keep their habitats healthy.

Niche n Some animals, like the pileated woodpecker, are insect eaters. They control insect populations in a community. He eats carpenter ants by chiseling them out of trees with its beak. Without animals like the woodpecker, insect populations could grow out of control.

DID YOU KNOW? ? . . . every organism in a community has a unique niche. n . . . one organism may have many niches in a community n