1. THE ECOSYSTEM

2. Introduction
Ecology is the study of the relationship between living organisms and their environment.
Environment is an organism’s immediate surroundings.
An ecosystem is made up of levels containing groups of organisms.

3. Ecological levels are as follows.
Individuals  Populations  Communities  Ecosystems  Biomes  Biosphere

4. Individual organisms of a single species make up a population.
Populations of more than one species makes up a community.
Communities make up an ecosystem.
Ecosystems make up a biome and biomes make up the biosphere.

6. Earth is made up of living organisms and inert substances.
It is the result of millions of years of evolution or change that is continuous.

7. The earth is a series of different ecosystems.
Each ecosystem has its own parameters for life.
These parameters include temperature, pH, and rainfall.

8. All species of plants and animals fit into ecosystems to which they have adapted.
Sometimes those parameters change.
When that happens, plants must adapt or die; animals must adapt, move, or die.

9. Early in the development of Earth, all water was fresh, including the oceans.
Over millions of years, water moved mineral salts through soil, down streams and rivers, and eventually to the oceans’ waters.

10. As the water evaporated back into the hydrological cycle, the oceans’ freshwater became brackish water and then eventually saltwater.
Photo by M. Jasek

11. People are part of the ecosystem.
People are the only species that can upset the balance in an ecosystem.
What appears to be a stable ecosystem, in fact, can be easily upset by over-exploitation of resources.

12. There is a misconception that humans will one day destroy the earth.
In reality, people may destroy the parameters needed for survival.
If the human population became extinct, the earth would heal itself and life without the human element would continue.

13. Ecosystem
A biotic community is a group of plants and animals that share the same area and environment.
In this community, plants and animals are interdependent.
Here biotic and abiotic components are constantly interacting.

14. Biotic components are all living organisms, from the smallest microbe to the largest animal.
Photo by E. B. Forsythe courtesy of U. S. Fish and Wildlife Service.

15. Abiotic components are non-living elements that include soil nutrients, water, air, and temperature.
Photo by Lynn Betts courtesy of USDA Natural Resources Conservation Service.

16. An ecosystem can be as large as a forest or ocean or as small as a river bank or tree cavity.
Each component in an ecosystem relies on others within the system for sustaining life.

17. A simple example of interdependency is as follows:
Herbivores eat plants.
Carnivores eat herbivores.
Both generate waste products that feed microbes, bacteria, and insects.
This helps feed the plants that herbivores eat.

18. Biomes
Biomes are large areas with a distinct combination of plants and animals.
These areas are influenced largely by latitude, soil, temperature, and rainfall.
The number of biomes may vary depending on how they are divided.

19. Biomes can be present on land or in water.
Aquatic biomes have their own set of characteristics.
On land, there are six major biomes in the United States.

20. Terrestrial Biomes
The six major biomes in the United States are classified as tropical, temperate forests, grasslands and savannas, tundra, taiga, and desert.

22. Aquatic Biomes
Water freshness is a measure of the amount of salt in the water.
The four levels of freshness are: fresh, brackish, salt, and brine.

23. ALL RIGHTS RESERVED
Reproduction or redistribution of all, or part, of this presentation without written permission is prohibited.
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Texas A&M University
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 2006