1. Lesson Overview
3.1 What Is Ecology?

2. Studying Our Living Planet
What is ecology?
Ecology is the scientific study of interactions among organisms and
between organisms and their physical environment.

3. Studying Our Living Planet
The biosphere consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere.
The biosphere extends from about 8 km above Earth’s surface to as far as 11 km below the surface of the ocean.

4. The Science of Ecology
Ecology is the scientific study of interactions among and between organisms and their physical environment.
Interactions within the biosphere produce a web of interdependence between organisms and the environments in which they live.

5. The Science of Ecology
Organisms respond to their environments and can change their environments, producing an ever-changing biosphere.

6. Ecology and Economics
Economics is concerned with interactions based on money.
Economics and ecology share the same word root. Indeed, human economics and ecology are linked. Humans live within the biosphere and depend on ecological processes to provide such essentials as food and drinkable water that can be bought and sold for money.

7. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Individual organism
On bison represents
an individual organism

8. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Population—a group of individuals that belong to the same species and live in the same area
A herd of bison (called a gang scientifically) represents a population of bison in an area.

9. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Community—an assemblage of different populations that live together in a defined area
The bison and elk (along with many other animals that live in Yellowstone Park) make up the community of organisms.

10. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Ecosystem—all the organisms that live in a place, together with their physical environment
The animals, plants, soil, air and water in Yellowstone Park are all part of the Yellowstone ecosystem.

11. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Biome—a group of ecosystems that share similar climates and typical organisms
Where we live in Wallace is part of the coniferous forest biome that stretches around the globe (see the light pink areas on the diagram at right).

12. Levels of Organization
Ecological studies may focus on levels of organization that include the following:
Biosphere—our entire planet, with all its organisms and physical environments
YOU ARE HERE!

13. Biotic and Abiotic Factors
What are biotic and abiotic factors?

14. Biotic and Abiotic Factors
What are biotic and abiotic factors?
The biological influences (living things) on organisms are called biotic factors. Physical components of an ecosystem (non living things) are called abiotic factors.

15. Biotic Factors
A biotic factor is any living part of the environment with which an organism might interact, including animals, plants, mushrooms and bacteria.
Biotic factors relating to a bullfrog might include algae it eats as a tadpole, the herons that eat bullfrogs, and other species competing for food or space.

16. Abiotic Factors
An abiotic factor is any nonliving part of the environment, such as sunlight, heat, precipitation, humidity, wind or water currents, soil type, etc.
For example, a bullfrog could be affected by abiotic factors such as water availability, temperature, and humidity.

17. Biotic and Abiotic Factors Together
The difference between abiotic and biotic factors is not always clear. Abiotic factors can be influenced by the activities of organisms and vice versa.
For example, pond muck contains nonliving particles, and also contains mold and decomposing plant material that serve as food for bacteria and fungi.

18. Biotic and Abiotic Factors Together
In addition, trees and shrubs affect the amount of sunlight the shoreline receives, the range of temperatures it experiences, the humidity of the air, and even the chemical conditions of the soil.
A dynamic mix of biotic and abiotic factors shapes every environment.

19. Ecological Methods
What methods are used in ecological studies?

20. Ecological Methods What methods are used in ecological studies?
Regardless of their tools, modern ecologists use three methods in their work: observation, experimentation, and modeling. Each of these approaches relies on scientific methodology to guide inquiry.

21. Observation
Observation is often the first step in asking ecological questions.
Questions may form the first step in designing experiments and models.
What kind of questions might be asked if you came upon this scene while studying a river?

22. Experimentation
Experiments can be used to test hypotheses.
An ecologist may set up an artificial environment in a laboratory or greenhouse, or carefully alter conditions in selected parts of natural ecosystems.
After finding the dead fish in the river, you might take samples of the water and test them for chemicals.

23. Modeling
Many ecological events occur over such long periods of time or over such large distances that they are difficult to study directly.
Ecologists make models to help them understand these phenomena.
You might set up an aquarium that simulated the conditions in the river and change things to see how it affects the fish.