Adaptations by Coniferous Plants

Though most of the trees in coniferous forests are evergreens, there are also some deciduous trees, such as aspen and birch. Unlike the tropical forest, where there is a mixture of many different kinds of trees, coniferous forests have many trees but of only a few kinds. Underneath the trees is a spotty layer of shrubs. Mosses and lichens grow on the forest floor as well as on the tree trunks and branches.

Since most water in coniferous forests is frozen during the winter, it is not available for plant roots to absorb it. Many evergreen trees, much like desert plants, are adapted to the scarce water supply because they have small leaves with a limited surface area and a waxy coating, which helps hold water in. Falling snow can collect on the limbs of trees with round or square crowns, causing the limbs to break. But the triangular shape of the crown of these trees and the needle-like shape of their leaves lets conifers more easily shed heavy snow buildups.

Adaptation is a structure or behavior that helps an organism survive in its environment (all the living and nonliving surroundings of an organism). One adaptation by coniferous plants to a short growing season in coniferous forests is their retention of leaves, which allows them to start photosynthesis as soon as temperatures permit in the spring, instead of having to spend time growing leaves. Another adaptation is the dark color of their leaves, which helps to absorb heat from sunlight.

Purpose

To demonstrate how the shape of a tree affects its ability to collect snow.

Materials

• newspaper
• two 6-by-10-inch (15-by-25-cm) pieces of poster board
• transparent tape
• spoon
• flour

Procedure

1. Unfold the newspaper and lay it on a table.
2. Fold one of the poster board pieces in half by placing the short sides together.
3. Partially unfold the folded poster board, creating a tent shape.
4. Stand the tent-shaped poster board on the newspaper and secure it to the newspaper with tape.
5. Tape one of the short ends of the other piece of poster board to the newspaper.
6. Bend this poster board to form a dome shape, then tape the other short end of this poster board to the newspaper.
7. Using the spoon, sprinkle 4 or more spoons of flour over the top of the tent-shaped structure. Observe how the flour builds up on the structure.
8. Repeat procedure 7, but use the dome-shaped structure.

Results

The tent-shaped structure held little to no flour, while most or all of the flour built up on the dome-shaped structure.

Why?

The tent shape, like the triangular shape of some conifers, doesn't provide a large surface area. Thus like the flour in this experiment, snow tends to slide off the leaves and branches. Though little flour built up on the tent-shaped poster board in the experiment, real triangular-shaped conifer trees have more surface area, so some buildup of snow does occur and some trees do collect more snow than others. At times the weight of the snow will cause tree limbs to break. This opens areas so that sunlight can reach the forest floor and more plants can grow there.

More Fun With Trees!

Pine trees have long thin needles that are grouped in clusters. Each cluster contains a specific number of needles, depending on the type of tree. Pines are divided into two groups, based on the hardness of their wood. The soft pines have needles in bundles of five. White pine is a well-known soft pine. The hard pines, such as red pine and pitch pine, have needles in bundles of two or three. Both soft and hard pine wood is used for lumber. Look at the needles from a pine tree. Count the needles in one cluster. Use the diagram to determine if the wood of the pine tree that the needles came from is soft or hard.

Book List

• NatureScope: Trees Are Terrific! Washington, D.C.: National Wildlife Federation, 1992. Information as well as indoor and outdoor activities about trees, including those in coniferous forests.
• VanCleave, Janice. Ecology for Every Kid. New York: Wiley, 1996. Fun, simple ecology experiments, including information about coniferous forests.

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Janice VanCleave's Science Around the World: Activities on Biomes from Pole to Pole
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