Chapter 3 Ecosystems: How They Work Copyright © 2008 Pearson Prentice Hall, Inc. Environmental Science Tenth 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 among Air, 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 than you started with. YOU CAN’T BREAK EVEN!

Example of the Laws of Conservation of Matter and Thermodynamics Global Warming Acid Rain Smog Burning Coal = CO 2 + SO + H 2 O + Ash + (C x H x S x O x ) 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

Photosynthesis Overview of Photosynthesis and Respiration

Explain how it is possible to grow a plant in a sealed jar. Photosynthesis 6 CO H 2 O C 6 H 12 O O 2 Respiration C 6 H 12 O O 2 6 CO H 2 O

Match Outcomes (Left) with Process (Right) Releases O 2 Stores energy Releases CO 2 Uses CO 2 Releases energy Produces sugar Uses sugar Uses O 2 Photosynthesis Cell respiration Both Neither

Match Outcomes (Left) With Organisms (Right) Releases O 2 Stores energy Releases CO 2 Uses CO 2 Releases energy Produces sugar Uses sugar Uses O 2 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 Levels Producer 10,000 Kcal Third-order Consumer Secondary Consumer Primary Consumer - 100x - 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 System

End of Chapter 3 PPT by Clark E. Adams