Chapter 3Ecosystems: How They Work

Copyright © 2008 Pearson Prentice Hall, Inc.

EnvironmentalScienceTenth Edition

Richard T. Wright

Ecosystems: How They Work

• Matter, energy, and life• Energy flow in ecosystems• The cycling of matter in ecosystems• Implications for human societies

Matter, Energy, and Life

• Matter in living and nonliving systems

• Energy basics

• Energy changes in organisms

The Four Spheres of Earth’s Environment

Elements of Life: A Summary

• Of the 94 naturally occurring elements in the universe, only 24 are utilized by living organisms.

• What elements would be considered harmful to living organisms?

Match the Elements (Left) with Molecules (Right)

• Nitrogen

• Carbon

• Hydrogen

• Oxygen

• Phosphorus

• Sulfur

• Glucose

• Proteins

• Starch

• Fats

• Nucleic acids

• All of the above

Atmospheric Gases

Water and Its Three States

Minerals: Dense clusters of atoms of two or more elements held together by the attraction of positive and

negative charges.

Na+ and Cl-

Interrelationships amongAir, Water, and Minerals

Organic Molecules

Levels of Organization in Living Things

Matter and Energy

• Matter: anything that occupies space and has mass.– Cannot be created or destroyed.– Can be changed from one form into another.– Can be recycled.– Can be measured where gravity is present.

Matter and Energy

• Energy: anything that has the ability to move matter, has no mass and does not occupy space.– Cannot be created or destroyed.– Can be changed from one form to another.– Cannot be recycled.– Can be measured.

Energy Conversions

Laws of Thermodynamics

First Law: (CHANGE) Energy is neither created nor destroyed but may be converted from one form to another. NO FREE LUNCHES!

Second Law: (LOSS) In any energy conversion, you will end up with less usable energy thanyou started with. YOU CAN’T BREAK EVEN!

Example of the Laws of Conservation of Matter and Thermodynamics

Example of the Laws of Conservation of Matter and Thermodynamics

Global WarmingGlobal Warming

Acid RainAcid Rain SmogSmog

Burning Coal = CO2 + SO + H2O + Ash +(CxHxSxOx) Light + Noise + Heat

Entropy: Energy Changes in Organisms

• Systems will go spontaneously in one direction only which is toward increasing entropy.

Entropy

First Principle of Ecosystem Sustainability

• Ecosystems use sunlight as their source of energy.

How Ecosystems Use Sunlight As Their Source of Energy

How Ecosystems Use Sunlight As Their Source of Energy

Photosynthesis

Overview of Photosynthesis and Respiration

Explain how it is possibleto grow a plant in a sealed jar.

Photosynthesis

6 CO2 + 6 H2O C6H12O6 + 6 O2

Respiration

C6H12O6 + 6 O26 CO2 + 6 H2O

Match Outcomes (Left) with Process (Right)

• Releases O2

• Stores energy• Releases CO2

• Uses CO2

• Releases energy• Produces sugar• Uses sugar• Uses O2

• Photosynthesis• Cell respiration• Both• Neither

Match Outcomes (Left) With Organisms (Right)Match Outcomes (Left) With Organisms (Right)

• Releases O2

• Stores energy• Releases CO2

• Uses CO2

• Releases energy• Produces sugar• Uses sugar• Uses O2

• Plants

• Animals

• Both

• Neither

Food Assimilation in Consumers

Violations of the First Principle of Ecosystem Sustainability

• Excessive use of fossil fuels.

• Feeding largely on the third trophic level.

• Use of coal or nuclear power.

• Use of agricultural land to produce meats.

Energy Flow in Ecosystems

• Primary production

• Energy flow and efficiency

• Running on solar energy– Freely available– Nonpolluting– Everlasting

Productivity of Different Ecosystems

Energy Flow Through Trophic LevelsEnergy Flow Through Trophic Levels

Producer 10,000 Kcal

Third-order Consumer

Secondary Consumer

Primary Consumer- 100x

- 10x

- 10x

100 Kcal

10 Kcal

1 Kcal

Energy Flow Through Trophic Levels

The Second Principle of Ecosystem Sustainability

• Ecosystems dispose of wastes and replenish nutrients by recycling all elements.

The Cycling of Matter in Ecosystems

• The carbon cycle

• The phosphorus cycle

• The nitrogen cycle

The Carbon Cycle

• How and in what form does carbon enter and leave the cycle?

• How is the role of autotrophs and heterotrophs different and the same?

• What are the human impacts on the cycle?

Global Carbon Cycle

Natural Production

Global Carbon Cycle

Human Activities

The Phosphorus Cycle

• How and in what form(s) does phosphorus enter and leave the cycle?

• How is the role of autotrophs and heterotrophs different and the same?

• What are the human impacts on the cycle?

The Nitrogen Cycle

• How and in what form(s) does nitrogen enter and leave the cycle?

• How is the role of autotrophs and heterotrophs different and the same?

• What are the human impacts on the cycle?

Nitrogen Cycle

Fundamental Aspects

Nitrogen Cycle

Interactive Exercise

Implications for Human Societies

• Ecosystem sustainability

• Value of ecosystem capital

• The future

Ecosystem Sustainability

• Ecosystems use sunlight as their source of energy

• Ecosystems dispose of wastes and replenish nutrients by recycling

Nutrient Recycling and Energy Flow Through an Ecosystem

Implications for Human Societies

• Ecosystem sustainability• Value of ecosystem capital• The future

The Human SystemThe Human System

The Human System

End of Chapter 3

PPT by Clark E. Adams