Climate, which is average weather conditions over a period of time, is the primary environmental influence on ecosystems.

Plants, animals, insects and microbes are adapted to small changes in climate. However, climatic conditions vary widely over the earth. Organisms adapted to Illinois would not do well in a desert or tropical climate. Even extremes in Illinois' climate can result in destruction of some members of the Illinois ecosystem.

The two most important climatic factors for ecosystems are sunlight and water.

Sunlight is necessary for plants to grow, and to provide energy to warm the earth's atmosphere. Light intensity controls plant growth. Light duration affects plant flowering and animal/insect habits.

All living organisms require some amount of water. Organisms in dry ecosystems are adapted to the conditions by storing water for use over long periods or becoming less active. At the other maximum, some plants and animals only survive by being submersed in water.

Objective of this Lesson

Students will become aware of climatic effects on ecosystems.

Materials Needed: Potting soil, three large styrofoam cups or small clay pots, three small tomato plants, florescent light or sunlight if available.

Instructions: Using the potting soil, plant the three tomato plants in containers. If using styrofoam cups, poke small holes in the bottom for water drainage.

Number each plant 1 through 3. Allow each plant to have the following amounts of light per day:

• Number 1- no light
• Number 2- 6 hours
• Number 3- continuous light

Record the growth of each plant for 10 days. Give each plant equal amounts of water regularly, keeping the soil moist but not saturated.

This activity should show differences in plant growth with differences in light.

Follow-up Questions

1. Which tomato plant grew the most? (The one receiving continuous light.)
2. Which plant grew the least? (The one receiving no light.)
3. How does sunlight affect plant growth?
4. Are there ways that a location on earth would receive less sunlight? (Volcanos could blow dust particles high into the atmosphere, decreasing sunlight reaching ground; a general increase in cloudiness would decrease sunlight as well.)
5. How would less sunlight affect an ecosystem? (Some plants may grow less if they need a lot of sunlight, some may grow more if they are shade tolerant; flowering patterns of plants may change; animal habits may change. Less sunlight may mean cooler air temperatures, bringing longer winters, and more or less precipitation.)

Materials Needed: Potting soil, two large styrofoam cups or clay pots, Kentucky Bluegrass seed.

Instructions: Place potting soil in the cups or pots. If using styrofoam cups, poke small holes in the bottom for drainage.

Plant the bluegrass seed, and allow it to grow until it is three inches tall. While it is growing to this height, keep the soil moist, but not saturated. After the grass is three inches, try this experiment with Sample 1, do not water it. With Sample 2, water it enough to keep the grass growing vigorously. Complete this routine until Sample 1 is almost completely brown. Begin watering Sample 1 at this point until it is growing vigorously again.

Follow-up Questions:

1. Can bluegrass survive without water? (Yes, for short periods of time. The bluegrass has the ability to go dormant during drought periods, and will begin growing when rainfall returns.)
2. Can all plants do this? (No, many plants will die.)
3. How do other plants adapt to short droughts? (Some will lose their leaves, some will quit growing, some will curl their leaves to prevent water from escaping).
4. How would more water affect an ecosystem that had adapted to periodic droughts? (Some plants could die, either because of too much water around their roots, or because flowering or growth may be hindered Other plants that like the extra water would thrive. More or larger animals may move into the ecosystem, since more water would be available. This could also change the existence of animals already in the ecosystem.)

Materials Needed: Encyclopedias or other books that describe desert climates, tropical rainforest climates, and mid-latitude temperate climates (climates similar to Illinois).

Instructions: Divide the class into three groups. Assign each group a climate, with each group developing a picture collage of plants, animals, and insects found in each climate. Once all groups are finished, have each describe what is found in those ecosystems. Have a class discussion on how each differs from the other, and if there are many similarities. Discuss what may happen if each ecosystem was changed by the following:

• Decreased sunlight
• Decreased water
• Increased water
• Increased sunlight