Every Tree for Itself
Duration: 30 – 40 minutes
Vocabulary: adaptations, competition, habitat, nutrients, taproot, photosynthesis
Summary: Students will act as trees and try to pick up popsicle sticks representing water, sunlight, and nutrients in order to learn how trees grow.
Objectives: Students will gain a deeper understanding of the conditions that trees need in order to live, and of the adaptations trees have developed in order to meet these needs.
Materials: popsicle sticks of three or four different colors (blue, yellow, and green are best), paper plates
Animals, including humans, all have adapted to be able to move around, whether it is by walking, flying, crawling, or sliding. This allows them to search for food, water, and shelter, and change the place they live to some extent if one place is not giving them what they need. Trees and other plants, however, cannot usually move! The place where the seed falls is where they have to stay. If there is not enough water, sunlight, or nutrients, the seed will not be able to grow at all.
Trees (and most other plants) are special because, unlike animals, they make their own food. They make food from sunlight using a process called “photosynthesis.” In this process they change sunlight into energy.
As mentioned above, all trees need water, nutrients, and sunlight, but different kinds of trees need different amounts of each. For example, a tree growing in a desert-like environment needs less water than a tree in the rainforest. A tree growing on the floor of the rainforest needs less sunlight than a tree growing in an open field. This is because different kinds of trees have adapted to living in different environments. For example, white pine trees (evergreens) have needles, which are very very small point leaves. This type of leaf collects less sunlight. Therefore, a pine tree can grow in a shady area. An oak tree, on the other hand, has broad leaves, and can collect more sunlight, and so it is adapted to live in more open environments.
Trees have also adapted different root systems in order to get water and other nutrients from the soil. Trees in wet environments usually have roots that are very shallow and branch out to the sides, while trees in dry environments have “tap roots”—a very long root that reaches deep into the soil in search of water. Some trees even have both!
Even though they can’t move, trees also have to compete with each other for water, nutrients, and sunlight.
Ask students to brainstorm some ways they could get the sunlight, water, and nutrients they need if they couldn’t move.
Have students “plant” themselves about three feet apart from each other while standing on a paper plate. The paper plate marks the spot where they have to stand, and at least one foot needs to be on the paper plate at all times and they are not allowed to move it.
Distribute the colored popsicle sticks on the floor evenly around the students. Yellow popsicles represent sunlight, blue represent water, and green represent nutrients like nitrogen, oxygen, and carbon dioxide. Give a signal to start the first round. Have students reach with their roots and branches (arms and legs) to gather their requirements. They need to try to get some of each in order to survive. Allow students to gather the popsicle sticks for one 30 second round. Have students count each color requirement they gathered. Ask them how many they got, and if they are missing any particular requirement. What might happen to a tree if it was missing a requirement in real life? Is there such a thing as too much water, sunlight, or nutrients? Yes!
Have students stand on their paper plates again but this time in groups of three or five. Play again for another 30-second period. Compare the results of this round to the first. In most cases, students will notice that each tree gathered fewer requirements in the second round. Ask if any trees “died” because they couldn’t get a particular requirement. Ask students to fall down or look droopy if they couldn’t get them.
Try other rounds with different scenarios, like having students close together but only allowing half of the class to gather nutrients, using fewer blue popsicles to represent drought, or fewer yellow ones to represent lack of sunlight, etc.
Ask students to explain what requirements trees have for survival, and how they might vary with trees in different places. Ask if they can reach any conclusions about trees growing close together based on the one scenario. Ask students how foresters might use their knowledge of competition and tree adaptations to plant and care for a stand of trees.
Have students research different types of trees, their adaptations, and requirements.
Have students write to or visit a local tree nursery to learn how the trees are cared for.