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Rain Forest Plants

 

Overview

From the oxygen we breathe to the food we eat, we owe our lives to plants. Plant variety is essential to life, and rain forests shelter more than half of all plant and animal species on earth. Rain forests straddle the equator in a belt called the tropics. The tropics receive more direct sun than the rest of the earth. That means more solar energy for photosynthesis - the process plants use to make food. This supports more plants, which in turn support more animals in the food chain. Rain forest plants compete with one another for scarce nutrients and for light and space to grow. Trees reach heights of 76 meters (250 feet). Many develop buttresses - roots that grow above ground from the trunk to create a wide, stable base for the tree. These are necessary due to the shallow depth of the roots. Shallow roots are present because there is fierce competition for nutrients among species at the surface of the soil. Leaves the size of dinner plates and high-climbing vines help some plants compete for light. No species can exist without the help of others. Orchids and bromeliads can grow as epiphytes - plants that grow with their roots anchored to surfaces of other plants. Bromeliads use other plants for support while they collect rain and water run-off from the foliage above. The pool in a bromeliad's center can hold a host of life, from insect larvae to tadpoles, lizards, and more. Indigenous people have always found many uses for the chemical substances that rain forest plants make to repel predators and diseases or to attract animals for pollination and seed dispersal. Chemists use these compounds as the basis of insect repellents, insecticides, flavorings, dyes, other industrial raw materials, and medicines. (The use of plants to help people is called ethno-botany .) Although some compounds are now reproduced synthetically, many others can be obtained only from the plants themselves. At least one-fourth of all prescription drugs have their origin in the rain forest. No one knows how many plants with powerful uses are still hidden away among vast numbers of unknown species. The most valuable thing about rain forests may not be what we know about them, but what we don't yet know.

Activity

Imagine life as an emergent rain forest tree. These trees grow very tall and often have many species living on them and in them. They need to stand up against high winds and soaking rains, yet they are anchored in a foundation of soil that's shallow and thin. How do they do it? Many grow buttressed roots. Buttresses come in different shapes, sizes, and thickness. Some are thin and flat. Others are twisted and branching. One scientist described a tree with such enormous buttresses and surface roots that it took a full five minutes to walk around it. Work in small groups to investigate how buttresses work. Materials (per group)
  • several sections, 15 to 30 cm (6"to 12") long, cut from ends of tree branches
  • shallow container such as a pie tin or deep paper plate, filled with 2.5 cm (1") of sand
  • cardboard, clay, small sticks, and other items to make buttresses
  • tape
  • fan or hair dryer to simulate wind
  • water can to deliver rain
1. Place the branches upright in the sand to represent an emergent rain forest tree. What happens when your "tree" is subjected to winds and rains? Make predictions and put them to a test. 2. What adaptations can you create with available materials to help your tree withstand wind and rain in the shallow soil? Test out your designs. 3. Which adaptations were most successful? Why? Questions
  1. How have buttresses in nature been "adopted" in human-made structures you have seen?
  2. How do climate and physical environments in different parts of the country affect the structure of plants?

Resources

    Amazon Center for Environmental Education and Research Foundation
    Ten Environs Park
    Helena, AL 35080
    (800) 255-8206
    (Bilingual teacher materials and "Adopt a School"
    information)
    Amazon adventure: Seventh-graders in the Amazon. (1993, Jan 15)
    Scholastic Scope, pp. 12 - 16.
    Lofty lessons of the rain forest: A treetop classroom in the Amazon.
    (1993, Mar 23) USA Today,p.1.
    A.C.E.E.R.: Amazon Rain forest Flora and Fauna. Slide set.
    (800) 255-8206.
    A Walk in the Rainforest with Dr. Jim Duke. Videotape (1994)
    traditional uses of medicinal plants. (800) 255-8206.
    National Gardening Association
    180 Flynn Ave
    Burlington, VT 05401
    (800) 538-7476
    [email protected]
    (Resource books for creating mini-ecosystems)
    Our featured contributor is International Expeditions, Inc.,
    sponsor of Rainforest Workshops for Educators and Students.
    For more information call (800) 633-4734 or e-mail
    [email protected]