Coniferous Forest Plant Adaptations

Problem:

Are coniferous or deciduous trees better at withstanding snow?

Materials

• 2 foot-long dowels
• Natural clay
• Two ½ foot squares of cardboard
• Flour sifter
• Flour
• 10 pieces of white paper
• Masking tape
• Newspaper
• Scissors
• 1 cup measuring cup

Procedure

1. To build your trees, cut out the squares of cardboard and put a chunk of clay on each one. Press one dowel into each piece of clay.
2. Spread newspaper on the floor, and put your trees onto the newspaper.  This experiment can get messy, so make sure that your trees are in the middle of the paper.
3. Cut your white paper in half, and fold the pieces until you have a long and narrow strip about half an inch wide. These will model your tree branches.
4. To attach the branches to the dowel, cut a hole in the middle of each folded strip with scissors.
5. Put the paper branches on the first tree. Start in the middle and angle the pieces of paper upward. Arrange the branches by alternating the orientation of the strip so that two form an “x” shape when viewed from above.  This is your deciduous tree.
6. Put the paper branches on the second dowel, which will model a coniferous tree. Start near the bottom and bend the branches slightly downward. Alternate the orientation of the pieces of folded paper as you did with the deciduous tree. If you want, you can make the branches gradually shorter as you near the top of the coniferous to make a more accurate model.
7. Create your snow by placing the flour in the sifter. Put 1 cup of flour into the sifter, and sift above the deciduous tree. Do the same above the coniferous tree. Does one tree hold snow? Does one tree shed more snow? What happens to the branches in the snow?

Results

The coniferous tree sheds snow more easily than the deciduous tree.

Why?

The branches of a tree are a place where birds can make a nest, and they’re lovely to sit under on a summer’s day. They also hold a tree’s leaves, allowing the tree to make food and grow.

Coniferous and deciduous trees are different in a number of ways. A coniferous tree makes cones, and these cones hold the tree’s seeds. Most coniferous trees are also evergreen. Evergreen trees slowly lose their leaves over the course of a year and all new leaves in the spring. In areas that are dark and cold, this allows evergreen trees to continue to make food throughout the fall and into the early spring, when there is a lot of water but not as much sunshine.

Deciduous trees have a different approach. A deciduous tree loses its leaves in the fall and grows new leaves in the spring. Usually these leaves are much broader than the little needle-like leaves of coniferous trees. The broad leaves of deciduous trees are great at collecting large quantities of light for photosynthesis.  They are also thin and disposable, and in the fall when light levels get lower, the trees let them fall to the ground.

When snow hits a deciduous tree, it usually piles up continuously on the tree branches. The round shape the branches form, as well as the branches that angle steeply upward, catch and hold a lot of snow. Over time, the weight can get too heavy and the branches can crack.

Coniferous tree branches may also, in some cases, crack in the snow, but a few coniferous characteristics make them more suited to handle snow than deciduous trees. Even though conifers still have “leaves” in the winter (we think of them as pine needles), they are small and narrow, causing snow to fall off of them more easily. When snow does settle on a coniferous tree’s branches, the shape of the branches and thickness of the needles allow the tree to withstand more weight because the branches have more surface area to support the weight. While some coniferous trees do have branches that slant slightly upward, they generally tend towards a horizontal position compared to deciduous branches.

The overall conical shape (pointy at the top and a steep downward slope) of coniferous trees also helps gravity slide the snow off onto the ground, just like might rock would tumble down a mountain. This is one reason that coniferous trees often form tree wells: the trunk is sheltered from the snow so effectively that there is a deep hole underneath the branches (that is generally hidden) in relation to the high snow level surrounding tree.

Digging Deeper

How do you think that each tree would hold up to rain? To wind? Can you think of an experiment to test these other elements? How might these effects be different in the winter and in the spring, when the deciduous tree has leaves?