Ecosystem

• All the organisms and abiotic factors in a community.

Ecosystem Studies

1. Energy Flow – the movement of energy through trophic levels.

2. Chemical Cycling – the movement of matter from one part of the ecosystem to another.

Trophic Levels

1. Primary Producers

2. Primary Consumers

3. Secondary Consumers

4. Detritivores

Primary Producers

• Usually plants, capture energy and store it in chemical bonds.

• Are the source of the energy available to an ecosystem.

Primary Consumers

• Organisms that feed on the producers.

• Ex: Herbivores

Secondary Consumers

• Organisms that feed on the Primary Consumers.

• Ex: Carnivores

Detritivores

• Get their energy from the organic waste produced by all levels.

• Ex: bacteria and fungi

Food Chain

• Linear pathway of who eats who in an ecosystem.

Food Webs

• Network showing all the feeding relationships in an ecosystem.

Energy Transfers

• Not 100% efficient.• Why?• Second law of

thermodynamics.• Waste.• Materials that can’t be

digested etc.

Energy Transfer

• Averages 10% with each Trophic Level change.

• Exam expectations – may give you data in energy units and ask you to calculate the %.

Question ?

• Why do most ecosystems have only 3 - 4 trophic levels?

• There isn’t enough energy passed up through the food web to support more levels.

Pyramids

• Graphical representation of relationships in ecosystems.

• Ex:1. Productivity

2. Biomass

3. Numbers

Chemical Cycling

• Matter is recycled through ecosystems.

• Ex: Biogeochemical Cycles

Representative Cycles

• Water

• Carbon

• Nitrogen

• Know one or more of these cycles for an essay question.

Energy vs Matter

• Energy - flows through ecosystems and is mostly lost as heat.

• Matter - cycles in ecosystems.

Question ?

• What is Man's influence on Ecosystems ?

• Humans have had many negative impacts.

Biological Magnification

• The concentration of toxins in successive levels of a food web.

• Ex: DDT Heavy metals

(Hg, Cd Pb)

Causes

• Not broken down by digestion/decomposition.

• Lipophilic.

• Concentrates and effects the upper levels of the food web.

Greenhouse Effects

• The trapping of heat by the Earth's atmosphere. (CO2, H2O).

Result

• Earth will heat up.

• Ice caps melt and sea levels will rise.

• Climate shifts.

• Increased Ps (?)

Habitat Destruction

• Worst problem threatening most species today.

Comment

• Man has a major impact on the Biosphere.

• Man needs to learn how to work with the Biosphere.

Summary

• Know the tropic levels of ecosystems.

• Know an example of a food chain and a food web.

• Know how energy moves through an ecosystem.

Summary

• Know how matter moves through an ecosystem.

• Know one or more examples of matter cycling.

• Be able to discuss in detail a human impact problem on ecosystems.

Thank You

• For all the work you’ve done this year (semester).

• For being attentive students that wanted to learn.

• For doing your best on the National AP Bio exam.