Energy in an Ecosystem

Get out your HW and grab your ecosystems…

Quiz: Get out a pencil and answer the question. Make sure to put your name/date on the paper

given to you.

If you start with 1000kg of biomass of primary producers, how much biomass would you have of…

1. Primary Consumers?

2. Secondary Consumers?

3. Tertiary Consumers

4. Why does a biomass diagram form a pyramid?

5. What is biomass?

Where does the Energy come from?

All the energy in an ecosystem comes from the sun.

1 - 2 % of the sun’s energy that strikes the earth is absorbed by plants

The rest is absorbed by abiotic objects or deflected to space

Plants use that energy through photosynthesis to produce sugar (glucose) which can then be converted to the biomass of the plant.

Biomass

Biomass – This is the mass of all matter at any level in a food chain

The amount of biomass in a food chain creates a pyramid (diagram).

Pyramid of Biomass

Approximately 10% of biomass at one level becomes biomass at the next level.

The other 90% is uneaten, undigested (this energy is available to decomposers) or given off as heat from the activities of the organism.

Decrease in Biomass

Biomass decreases with each additional step upward in a food chain.

Energy is lost as heat (and cannot be reused) in each step of the food chain (diagram on next slide)

Pyramid of Numbers This is a pyramid

showing that a large number of organisms (see primary productivity) is required at the base of the food chain (there are exceptions) to support a small number of organisms at the top.

Biomass Pyramid Video

http://www.youtube.com/watch?v=NJplkrliUEg

Answer these questions…

The number of organisms at the highest level in a food chain is directly related to the number of levels in the chain. How can more organisms be supported in an ecosystem?

What is the difference between a pyramid of biomass and a pyramid of numbers?