Backyard Science—The Secrets of Winter Trees
Here in the Northern Hemisphere, deciduous trees stand quietly waiting to be dressed in spring clothes. The air is quiet. Perhaps there is snow. It is time to walk among the winter trees and see what secrets their leaves have been hiding all summer long.
Before You Go
Before you head outside, pick a good place for your walk. A local nature trail is nice. A stroll around the yard or neighborhood might work better for really little ones. Just make sure there are smaller trees or shrubs at or near the eye level of the younger members of your group, so they can enjoy too. Oh, and be sure to dress for the weather. Here in Western Washington, a winter walk usually calls for warm clothes and rain jackets. Maybe you’ll be lucky enough to need snow boots and gloves.
Discussion Questions Along the Way
As you walk, talk about the winter landscape. How is it different from summer? What is missing? What is the same? Ask kids why they think trees lose their leaves. They may have already learned the reasons in school—at any rate, it’s fun to hear their answers.
Why Do Trees Lose Their Leaves?
Trees lose their leaves to protect themselves from winter’s harsh, freezing conditions. Leaf tissue is vulnerable to freezing and drying out, so trees reabsorb essential nutrients from their leaves (this creates all the wonderful colors) and then form a layer of cells between the tree and the leaf. Once the connection between tree and leaf has been severed, the leaf dies and falls from the tree. If left in place, it will decompose and enrich the soil, further supporting the tree.
Winter Tree Secret #1
The first secret winter trees reveal is shape. Most of the year, leaves hide the basic shape—the skeleton, if you will—of the tree. In winter, these shapes are fully visible. Some trees can even be identified by their winter shapes. Seattle Tilth has a webpage devoted to beginning winter tree identification: http://seattletilth.org/learn/resources-1/almanac/december/wintertreeid
Winter Tree Secret #2
The second secret winter trees reveal are buds. Buds are next year’s leaves and flowers, tightly wrapped in tough packaging. Buds give a tree or shrub a head start in the growing season. As soon as day length and weather conditions are favorable, the bud lengthens and a leaf unfolds, already ready to begin its work as a photosynthesis powerhouse. If the tree had to wait until spring to start a leaf from the very beginning, it would take several weeks for it to begin making food.
As you make your way along your chosen path, check out the buds on different trees and shrubs. What is the same about the different buds? What is different?
Winter Tree Secret #3
The third secret winter trees reveal is the very best—nests! During the nesting season, nests are hidden by leaves. This is great protection for baby birds, but makes spotting them difficult at best. In the winter, nests become obvious aberrations in the shapes of winter branches. Look for large, messy leaf blobs, which are squirrel nests, and cup-shaped, mud-reinforced robin nests. Look for unusual manmade materials incorporated into nests.
If you are interested in trying to identify more of the nests you see, there are field guides for nests and eggs available to buy or to check out from your local library. The Peterson Field Guides series has a guide to both Eastern and Western birds’ nests.
You can also type in “bird nest identification” into a web search. This site specific to birds of the Eastern U.S. came up when I looked. It contains some good information: http://northernwoodlands.org/articles/article/which-bird-made-that-nest/
After You Get Back
Of course, hot chocolate should follow a nippy winter walk. As you sip your cocoa, enjoy these tree-themed books with the kids:
Winter Trees, by Carole Gerber
Sky Tree, by Thomas Locker
A Tree is Growing, by Arthur Dorros
Have You Seen Trees? By Joanne Oppenheim
Night Tree, by Eve Bunting
Where Would I Be in an Evergreen Tree? By Jennifer Blomgren