Energy in an EcosystemEnergy in an Ecosystem

Science 10Science 10

Capturing Energy From the SunCapturing Energy From the Sun

All living organisms require energy in All living organisms require energy in order to support lifeorder to support life

The only source of energy available The only source of energy available to the Earth comes from the Sunto the Earth comes from the Sun

Therefore, this energy must be Therefore, this energy must be captured by some organisms in order captured by some organisms in order to power life on Earthto power life on Earth

EcosystemEcosystem

An ecosystem describes all of the An ecosystem describes all of the organisms within a given area and organisms within a given area and how they interact with their how they interact with their environment and each otherenvironment and each other

We could consider an ecosystem as We could consider an ecosystem as large as the Earth or as small as a large as the Earth or as small as a fish tank depending on the scale we fish tank depending on the scale we wish to investigatewish to investigate

Energy From the SunEnergy From the Sun

Energy from the sun is captured by Energy from the sun is captured by green plants through the process of green plants through the process of photosynthesisphotosynthesis

Plants are able to take water from Plants are able to take water from the Earth and carbon dioxide from the Earth and carbon dioxide from the atmosphere and combine them the atmosphere and combine them to form sugar and release oxygento form sugar and release oxygen

This process requires sunlight and This process requires sunlight and chlorophyllchlorophyll

ProducersProducers Any organism that is Any organism that is

able to produce its able to produce its own food is called a own food is called a producerproducer

Producers are able to Producers are able to capture energy from capture energy from the sun through the sun through photosynthesisphotosynthesis

This energy will be This energy will be stored in chemical stored in chemical compounds within the compounds within the plantplant

Primary ConsumersPrimary Consumers

Primary Consumers Primary Consumers are organisms that are organisms that get the majority of get the majority of their energy from their energy from producersproducers

They are called They are called herbivoresherbivores

Examples would be Examples would be deer, rabbits and deer, rabbits and cowscows

Secondary ConsumersSecondary Consumers

Secondary Secondary Consumers are Consumers are organisms that organisms that feed primarily on feed primarily on primary consumersprimary consumers

They are called They are called carnivorescarnivores

Examples would be Examples would be coyotes, bobcats coyotes, bobcats and spidersand spiders

Tertiary ConsumersTertiary Consumers

Tertiary Consumers Tertiary Consumers are those who are those who would feed would feed primarily on primarily on secondary secondary consumersconsumers

They are called top They are called top carnivorescarnivores

Examples would be Examples would be polar bears and polar bears and eagleseagles

Trophic LevelsTrophic Levels

When we consider an ecosystem, it is When we consider an ecosystem, it is often useful to consider the trophic often useful to consider the trophic (or feeding) levels within the (or feeding) levels within the ecosystemecosystem

Most ecosystems would have four Most ecosystems would have four trophic levels although more are trophic levels although more are possiblepossible

Trophic LevelsTrophic Levels

First Trophic Level First Trophic Level – Producers– Producers

Second Trophic Second Trophic Level – Primary Level – Primary ConsumersConsumers

Third Trophic Level Third Trophic Level – Secondary – Secondary ConsumersConsumers

Fourth Trophic Fourth Trophic Level – Tertiary Level – Tertiary ConsumersConsumers

Energy LossEnergy Loss

10% Rule10% Rule• This rule states that for each trophic This rule states that for each trophic

level, there will be approximately 10% level, there will be approximately 10% of the energy available to the next of the energy available to the next trophic leveltrophic level

For exampleFor example• Sun’s Energy – 100JSun’s Energy – 100J• Grass – 10JGrass – 10J• Deer – 1JDeer – 1J• Lion – .1JLion – .1J

Pyramid of NumbersPyramid of Numbers

Since each trophic level has less Since each trophic level has less energy available than the previous energy available than the previous level, the population normally level, the population normally decreases as the trophic level decreases as the trophic level increasesincreases

So for an ecosystem with 100 000 So for an ecosystem with 100 000 plants, there may only be 2 tertiary plants, there may only be 2 tertiary consumersconsumers

Pyramid of BiomassPyramid of Biomass

In some cases the pyramid of In some cases the pyramid of numbers won’t work; for instance if numbers won’t work; for instance if you have a very large producer you have a very large producer compared to the size of primary compared to the size of primary consumersconsumers

This is most evident in the life that This is most evident in the life that can be supported by a tree; one tree can be supported by a tree; one tree may support millions of insectsmay support millions of insects

In this case, a pyramid of biomass is In this case, a pyramid of biomass is more useful to considermore useful to consider

Food WebFood Web

We can use a web to indicate all of We can use a web to indicate all of the organisms within an ecosystem the organisms within an ecosystem as opposed to using a pyramid or as opposed to using a pyramid or food chainfood chain

How Big is 7 000 000 000?How Big is 7 000 000 000? As the human population on Earth As the human population on Earth

has exceeded seven billion, it is has exceeded seven billion, it is interesting to consider this numberinteresting to consider this number• At 1 number per second, how many At 1 number per second, how many

years would it take to count to 7 billion?years would it take to count to 7 billion?• If you made $7 billion in your career (40 If you made $7 billion in your career (40

years), what would your hourly wage be years), what would your hourly wage be (assume 52 weeks/year, 40 (assume 52 weeks/year, 40 hours/week)?hours/week)?

• If you had 7 billion pennies, with a If you had 7 billion pennies, with a thickness of 1.6mm, how many km’s thickness of 1.6mm, how many km’s tall would the stack of pennies be?tall would the stack of pennies be?