How Ecosystems Work

How Ecosystems WorkEnvironmental Science

Ms. Moore10/10/13

Life Depends on the SUN

• Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules in a process called photosynthesis.

• 6CO2 + 6H2O + solar energy C6H12O6 + 6O2

• CARBON DIOXIDE + WATER + SUN YIELDS CARBOHYDRATES + OXYGEN

So, What eats What?Energy Source Examples

ProducerMakes its own food through photosynthesis or chemical

sources

grasses, ferns, cactuses, flowering plants, trees,

algae, and some bacteria

ConsumerGets energy by eating producers

or other consumersMice, starfish, elephants, turtles, humans, and ants

Types of ConsumersEnergy Source Examples

Herbivore ProducersCows, sheep, deer, and

grasshoppers

Carnivore Other consumersLions, hawks, snakes,

spiders, sharks, alligators, and whales

Omnivore Both producers and consumersBears, pigs, gorillas, rats, raccoons, cockroaches,

some insects, and humans

DecomposerBreaks down dead organisms in an

ecosystem and returns nutrients to the soil, water, and air

Fungi and bacteria

Energy Transfer

• A food chain is a sequence where energy is transferred from one organism to the next as each organism eats another.

• A food web shows many feeding relationships that are possible in an ecosystem.

Tropic Levels

• Each step where energy is transferred in a food chain is known as a trophic level.

• Energy pyramid:– Producers: 1,000x energy– Primary Consumers: 100x energy– Secondary Consumers: 10x energy– Tertiary Consumers: 1x energy

Mini Lab

• In groups of 3-4:– Create a food chain: each person will act as an

organism of your choice– Create a food web poster including 10 organisms:

draw and label each organism (example on page 130)

– Create a trophic pyramid: each person will create their own pyramid in the groups

– Answer questions along with pyramid project

The Cycling of Materials

• The CARBON CYCLE cycles carbon between the atmosphere, land, water, and organisms.

• The NITROGEN CYCLE is a process where nitrogen is cycled between the atmosphere, bacteria, and other organisms.– All organisms need nitrogen to build proteins

(cells)– Nitrogen fixing bacteria: alter nitrogen so we can

use it

• The PHOSPHORUS CYCLE is the movement of phosphorus from the environment to organisms and then back to the environment– Needed to form bones and teeth in animals

How Ecosystems Change

• Ecological Succession is a gradual change of all or some of the species in a community

– Primary Succession occurs on a surface where no ecosystem existed before (rocks, sand dunes)

– Secondary Succession occurs on a surface where an ecosystem has previously existed

Secondary Succession

• Pioneer species: the first orgfanisms to colonize any newly available area

• Climax community: a final and stable community

• Example: Volcanic eruption– See page 138

Fire and Secondary Succession

• Natural fires caused by lightning is a natural cause of secondary succession.

• Example: Yellowstone’s fires

• Case Study on page 138-139

Old-Field Succession

• Old-Field Succession: occurs when farmland is abandoned– pioneer grasses and weeds grow rapidly and

produce many seeds to cover abandoned land

• Figure 19 on page 140