1. Ecosystems: What Are They and How Do They Work?
Chapter 3

2. 3-1 What Is Ecology?
Concept 3-1 Ecology is the study of how organisms interact with one another and with their physical environment of matter and energy.

3. 3-1 What Is Ecology? Ecology is a study of connections in nature.
How organisms interact with one another and with their nonliving environment.

4. Species Make Up the Encyclopedia of Life
Organisms – individual forms of life
Classified into species based on certain characteristics
Species – a set of individuals that can mate and produce viable, fertile offspring
1.75 Million species identified
Up to 10–14 million species not yet identified??
Insects make up most of the known species

5. Science Focus: Have You Thanked the Insects Today?
Many times we classify insects as pests:
Compete with us for food
Spread human diseases
Bite or sting us
Can be a nuisance
However, they are VERY beneficial:
Pollinators
Eat other insects
Loosen and renew soil
Estimated $57 billion/yr in ecological services

6. Species Make Up the Encyclopedia of Life
A population is a group of interacting individuals of the same species occupying a specific area.
The space an individual or population normally occupies is its habitat.

7. Species Make Up the Encyclopedia of Life
Genetic diversity
In most natural populations individuals vary slightly in their genetic makeup.
These genetic diversity is crucial to the survival of the population.

8. Levels of Organization of Matter in Nature
Populations of different species living and interacting in an area form a community.
A community interacting with its physical environment of matter and energy is an ecosystem.
The biosphere is where all of the Earth’s life is found
A “global ecosystem”

9. 3-2 What Keeps Us and Other Organisms Alive?
Concept 3-2 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

10. Natural Capital: General Structure of the Earth
The biosphere consists of several physical layers that contain:
Air
Water
Soil
Minerals
Life

11. The Earth’s Life-Support System Has Four Major Components
Biosphere – All of the life on the planet
Atmosphere – Membrane of air around the planet.
Troposphere – lowest layer - most gas of any layer
where weather occurs
Stratosphere – contains ozone to filter out most of the sun’s harmful UV radiation.
Hydrosphere – All the earth’s water: liquid, ice, water vapor
Geosphere – The earth’s crust and upper mantle
Lithosphere – hard outer crust
Asthenosphere – molten interior

12. Three Factors Sustain Life on Earth
One-way flow of energy beginning with the sun
Follows the laws of thermodynamics
Most is lost as heat
Cycling of matter or nutrients
Nutrients exist in a fixed amount
Follows the law of conservation of matter
Gravity

13. Flow of Energy to and from the Earth
Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth.
Natural greenhouse effect – natural process that keeps the Earth warmer than it would otherwise be

14. Life Exists on Land and in Water
Life exists on land systems called biomes and in freshwater and ocean aquatic life zones.