Lesson 1
The Web of Life
Talk About Trees
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Focus:
1. Establish the concept of "community" by having students think of various types of human communities, for example:
  • our planet
  • our state
  • our neighborhood
  • our classroom
  • our country
  • our city
  • our school
  • our families
2. Establish the concept of "ecological communities" by identifying the Greek words "oikos" (house) and "logos" (the study of) as the basis of our word "ecology". Ask the class to guess what the "house" is in an ecological community (the environment). Ask the class to think of some ecological communities. Write them on the board.
Below are some suggestions:
  • the forest
  • an open field
  • a stream
  • someone's yard
  • a fallen log
  • the ocean
  • a lake
  • a park
  • a fish tank in someone's house
  • our bodies
Ask the student to guess some of the members within the ecological communities that they have identified.
Following are some suggestions:
the forest: trees, shrubs, wildlife, insects, fish, people, fungi (such as mushrooms), bacteria
the ocean: fish, mammals (such as whales), crustaceans (such as shrimp), mollusks (such as clams), seaweed, algae, bacteria
an open field: mice, birds, insects, worms, fungi, bacteria, plants
a lake: plants, fish, insects, birds, people
a stream: fish, insects, plants, wildlife, birds
a park: trees, flowers, birds, animals, insects, people
someone's yard: trees, plants, birds, animals, insects, people
a fish tank in someone's house: fish, plants, algae, insects, bacteria
a fallen log: fungi, moss, insects, animals, bacteria
our bodies: cells, bacteria, viruses

3. Establish the concepts on interdependence, feedback mechanisms, and natural balance by asking the students to guess what patterns all ecological communities share in common. Examples are given below:
They all need energy (food) to survive.

The success of the community depends on the success of the individuals. This is an example of interdependence.

The success of the individuals depends on the success of the community. This is also an example of interdependance.

The indidviduals within a community respond to changes in their environment by adapting. This is an example of feedback.

The community is altered in response to changes by individuals within that community. This is an example of how ecological systems move toward natural balance.


Objectives:
1. To understand the concept of ecosystems

2. To understand the interdependence of all members of a community


Skills:
1. Association
2. Math
3. Ecology
4. History
5. Logic
6. Art
7. Language


Vocabulary:

Web of Life - The network of relationships that interconnect all species of an ecological community

Ecology - The study of how plants and animals interact with their environment

Environment - The conditions or elements that surround an ecological community or its members

Feedback - The return of information about the result of a process or activity. It often results in change by the receiver of the feedback information.

Balance - A state of equilibrium or stability

Energy - A source of usable power, such as sunlight or food

To get a printable student vocabulary handout click below
4. Establish background for a writing activity on the Web of Life by asking if any of the students have ever played billiards or marbles. Ask them to point out what happends when one ball or marble hits another.
It affects the rest of the balls or the marbles.
Ask the students if they have ever driven bumper cars at an amusement park. Have them relate what hapens when one car bumps another.
Other cars get rearranged.
They often hit adjacent cars, in turn.
Indicate to the students that this same dynamic process is what occurs in all ecological communities.
When something happens to one portion of an ecological community, everything else connected to it is affected too.
5. Share with the students the following example of a forest ecosystem in light of the Web of Life, where change in one aspect of the ecological community elicits a change in another.
In a part of the forest, juicy seedlings have successfully competed with bitter plants for sun, water, and nutrients. Now there are plenty of juicy seedlings and fewer bitter plants. Deer love juicy seedlings. They don't like to eat bitter plants. The deer discover this good feeding area and begin to browse freely. Over time, the deer population flourishs with the abundant food. The number of juicy seedling goes down as they are eaten by larger numbers of deer. Since the bitter plants are not eaten by deer, and there are no longer as many juicy seedlings to compete with, bitter plants now flourish. With an increasing number of bitter plants and fewer tasty seedling to feed on, the larger population of deer does not have enough to eat. Deer leave the area. As fewer deer remain to eat the juicy seedlings, these seedlings flourish once again, successfully competing with other plants in the area. Increasing numbers of juicy seedlings draw deer back into the area.
To help the students vsualize the process, draw a double flow chart, as indicated on the sheet provided. This will illustrate feedback changes and prepare the class for the following activity.

6. Student writing activity:

Preface the activity by explaining that John Muir, California naturalist, once said:

"When we try to pick out anything by itself, we find it hitched to everything else in the universe."
Ask the class to interpret what Muir was saying.
All members of an ecological community are connected by the Web of Life.
What happens in one part of it affects all the other parts.
Reinforce the concept of interdependence by reminding the class that nature has many ways to maintain/restore balance in an ecological community.

Read the following two stories aloud. Ask the students to think about the scenes. Have them discuss then describe what is happening in these ecological communities by writing a paragraph or completing a flow chart, such as follows this lesson.

Community One

On a hillside in the forest, there is enough water to grow 100 healthy trees. Over many years, as the result of no fires, no insects, no diseases, and no harvesting of trees the area has become overgrown. Now, there are 1000 trees competing for sunlight, nutrients (food), and water.

In what kind of health are many of those 1000 trees?
They are severely stressedand me prone to fire, disease, and insects.

What eventually happens to most of the stressed trees?
They die.

What happens to the animals and insects that make use of all those trees?
Insects in the area will flourish as they invade the stressed trees. They will grow to epidemic levels because they can easily spread among the overcrowded trees.

Animals often lose their homes and sometimes lose their lives in wildfires that become out-of-control in areas where there are lots of dead and dying trees.

What happens if some of thse trees are thinned?
The remaining trees will be healthier.

Community Two

An area of the forest has lots of small shrubs and seedlings. It has very few large trees. It is a perfect home for mice. Since owls love mice, this is also a good hunting ground for owls. Over time, though, the seedlings and saplings in this area grow into older, taller trees which crowd together. The bushes, shrubs, and seedlings cannot get enough sun, water, and nutrients to grow in this area.

What happens to the mice as shrubs, bushes, and seedlings disappear?
They find new homes in other areas that provide more food and safety

What happens to the owls?
They will have to hunt in other areas where they will be able to find mice.

What happens to the crowded trees?
They become stressed and are more likely to die of disease, insects, and fire.

What happens if the trees are thinned?
The trees that remain will be healthier.
Thinning will allow more sun, water, and nutrients to reach smaller plants.
The smaller shrubs and plants will bring back the mice.
The return of the mice will bring their predators back into the area.

Enrichment Activity:
Have the students work the WHEEL OF FORTUNE and MEMORY MAGIC puzzles. Memory magic will be more challenging for the younger students.

Other Materials Needed:
Forest Flowchart Memory Magic Crossword Wheel of Fortune
Forest Flowchart Answer Key Memory Magic Answer Key Wheel of Fortune Answer Key