1. World Geography 3202
Unit 3
Ecosystems

2. Introduction
Unit 3 focuses on the interrelationships between landforms and water forms on the one hand and climate on the other, and how these interrelationships make up the earth’s ecosystems.
Soils, which result from a complex interaction among climate, land, flora and fauna, form a vital resource that humans use to satisfy needs and wants.
Humans must exercise wise stewardship in order to conserve resources

3. An ecosystem consists of a complex network of organisms
Ecosystem: The network of relationships among plants, animals and the non-living constituents in the environment.
It is composed of:
Producers: Organisms capable of making their own food supply from solar energy, thus making them necessary for supplying the energy for all of life.
Consumers: Animals that must eat producers and other consumers in order to survive
1 Define the term ecosystem

4. An ecosystem consists of a complex network of organisms
Decomposers: Live in soil or water and include bacteria, fungi, and mold.
They break down wastes of other consumers and the decaying tissue of dead organisms into basic chemical compounds and nutrients.
These decomposed substances are returned to the environment to be reused by plants for growth and food production.
Primary Consumers: Herbivores, those animals whose only source of energy is green plants.
Secondary Consumers: Those organisms who survive on the energy of producers and primary and secondary consumers

5. Ecosystem

6. An ecosystem consists of a complex network of organisms
Starting with the sun, sending it’s energy to plant producers, and continuing on through every instance of one organism consuming another, energy is constantly begin transferred, or passed on, through life forms.
This transference is called a Food Chain
Differentiate the terms food chain and food web

7. An ecosystem consists of a complex network of organisms
A food chain is relatively simplistic, often with five links or less:
Producer --- Primary Consumer --- Secondary Consumer --- Tertiary Consumer
In most ecosystems, there are many overlapping food chains, because most organisms obtain energy from different sources.
Consequently, the relationship of organisms in competition for various energy sources in a given ecosystem is better described as a Food Web
Differentiate the terms food chain and food web

8. Food Web
Differentiate the terms food chain and food web

9. Energy flow through an ecosystem
Solar Energy is delivered to plants
Plants deliver oxygen to atmosphere, take in Carbon Dioxide, and serve as food for Primary Consumers
Primary Consumers are consumed by Secondary Consumers
Secondary by tertiary, and so on…
At each level of transference, energy is lost: only 10 to 15 percent of the energy used by the food source is consumed by the next level… Therefore secondary and tertiary consumers are terrible energy wasters
Outline the energy flow through an ecosystem

10. Energy flow through an ecosystem
Outline the energy flow through an ecosystem

11. Food Pyramids
The food pyramid diagram can be used to illustrate energy flow in food chains and food webs.
The pyramid shape of the diagram derives from the fact that a steadily decreasing amount of energy is available at each new level in the food chain.
As a result of competition, the number of organisms that can be supported at each new level decreases.
Explain why there are fewer organisms at each trophic level

12. Food Pyramids
Explain why there are fewer organisms at each trophic level

13. Food Pyramids
The base of the pyramids represents the amount of energy supplied by all the plants or producers in an ecosystem.
The layer above the base represents the number of primary consumers that can be supported by the producers
The layering continues until, in theory, only one carnivore can be supported at the top.
Each of these layers is known as a Trophic Level.
Explain why there are fewer organisms at each trophic level

14. Biological Amplification :
The relationships among the living and non-living elements of an ecosystem are delicately balanced
Biological Amplification :
When consumers at higher levels in a food chain eat organisms that have toxic chemicals in their tissues, they receive a higher concentration of the toxins than did the lower level organisms.
Two factors are involved in this magnification.
First: Toxic chemicals are fat soluble. This means they collect in fatty tissues and do not get flushed with waste.
Second: The higher up the food chain an organism is, the more of organisms it has to consume to keep energy levels up, as it only receives approximately 10 percent of that organism’s energy in transference.
Define the term biological amplification
With reference to a food pyramid, explain how pesticides can reach toxic levels for organisms at
a higher trophic level