Energy in EcosystemsEnergy in Ecosystems

The Source of it All…The Source of it All…

• The source of all energy used in ecosystems is the Sun.

• The energy given off by the Sun is incredible but we actually make use of very little of it.

• What happens to the Sun’s energy?• About 30% is reflected by clouds or the surface of

the Earth.• About 70% heats the Earth’s surface and/or

evaporates water.• Only a tiny portion – 0.023% - is used for

photosynthesis – the process by which plants make food.

The Albedo EffectThe Albedo Effect

• Albedo is a measure of the amount of sunlight that an object reflects. The higher the albedo – the more light it reflects.

• This plays a role in the global temperature as objects like clouds and snow reflect a lot of the light that strikes them.

• As the greenhouse effect continues to increase the temperature of the Earth, we will see more and more of the Earth’s snow melt and further decrease the amount of reflected light. The lower albedo means more energy absorbed and higher temperatures still.

Following Energy MovementFollowing Energy Movementin Ecosystemsin Ecosystems

The Flow of EnergyThe Flow of Energy

• Energy is passed on between organisms by eating – one organism eats another and gets energy from it – we call it food!

• The flow of energy through an ecosystem follows the “Who eats what (or who)?”, of the ecosystem.

• Al living things belong to a specific level in the ecosystem based on what they eat – these are called trophic levels.

Trophic LevelsTrophic Levels• The first trophic level that must be addressed are the

autotrophs – these organisms make there own food using photosynthesis. The term “autotroph” literally means “self feeding”.

• Autotrophs are also known as producers.• The autotrophs are important because they are the

only ones that can absorb the energy of the Sun and make it available to all of the other organisms.

• After the autotrophs, you have various levels of heterotrophs – organisms that must eat other organisms to gain their energy – they cannot make their own.

• The term “heterotroph” means “different eating”.

HeterotrophsHeterotrophs• Heterotrophs are also known as “consumers”.

• The first level of heterotrophs are the primary consumers – these are the organisms that eat the producers in the ecosystems – they are plant-eaters.

• Primary consumers are herbivores or omnivores.

• Secondary consumers eat the primary consumers. Secondary consumers are carnivores.

• The top level consumers are termed tertiary consumers and they eat secondary consumers.

Food Chains & Food WebsFood Chains & Food Webs

• A food chain is a diagram showing a step-by-step diagram of who eats who.

• At the base of every food chain is an autotroph/producer. This is where energy enters the food chain for everyone else to use.

• A food web is a diagram that shows many of the organisms in an ecosystem in a series of related food chains.

Food ChainsFood Chains

Food WebsFood Webs

Limits on Energy TransferLimits on Energy Transfer• When an organism produces or eats food – the energy

from that food starts to be used almost instantly.• The energy from the food will be used for…

• Heat (AKA Thermoregulation)• Metabolism• Growth• Immune response

• All of these require energy conversions which lose energy.

• After all of this energy has been accounted for, there is only about 10% of the energy left over for the organism that eats this one. This passing on of 10% of the energy is known as the 10% rule.

Ecological PyramidsEcological Pyramids• There are several types of pyramids that can be used to

represent the energy flow in an ecosystem. All of the pyramids take a food chain and use the members of the food chain for each level in the diagram.

Pyramid of Energy• This type of pyramid illustrates the 10% rule of energy

transfer.

Pyramid of Numbers• This pyramid shows the number of each organism at

each trophic level.

Pyramid of Biomass• Shows the mass of all of the members of each trophic

level in the food chain.

Energy PyramidsEnergy Pyramids

Pyramid of NumbersPyramid of Numbers

Pyramid of BiomassPyramid of Biomass

Pyramids – What to Look For…Pyramids – What to Look For…

• A pyramid of energy will always show the 10% rule and will always look like the traditional pyramid.

• A pyramid of biomass will also always look like a traditional pyramid because the mass of the organism is its tissue and this is where the energy is found.

• A pyramid of numbers may look like the traditional pyramid or may take on the shape of a top (the spinning toy). It depends on the size of the producer found within the ecosystem. Smaller produces give pyramids and large producers give tops.

THE END!!!