Step, kick, crrrrunch!

It's the SOUND of fall!

What to look for:

This is a
Sugar Maple Leaf.

Find a tree with leaves shaped like the one shown here.

Tell us when the ground under the tree is colored orange, red, or yellow, and the branches are bare.

There are five kinds of maple trees in Minnesota: sugar, red, silver, black, and mountain maple. All maples have palmately-veined leaves (shaped like your hand with your fingers and thumb spread out) and opposite branching. You can be sure the leaf from your tree is a Sugar Maple by checking its shape on this on-line tree key.

Watch in your neighborhood and around school. If you think you are the first person to see this event, ask your teacher to submit your name to the Wolf Ridge website (see table below.)

Where do Sugar Maples live?
Sugar maples grow in most of the Fall Happenings forested areas. They are common in the temperate deciduous forests, but occur only occasionally in the coniferous forests of the north near the Canadian border. Some of you might need to watch Red Maples instead - just let us know in the comments section when you report the event.
How do leaves get off the trees after being stuck on all summer?

They go down!

OK, there's more to it than that . . .

Deciduous trees (trees that lose their leaves each year) keep their leaves as long as it is warm, wet, and sunny enough to keep making food from water and carbon dioxide using the sun's energy. When temperatures get colder and the days get shorter in late summer and fall, leaves can't make as much food .

With out as much food, the tree slows down and prepares to loose its leaves for winter. Trees have a special way of letting leaves fall off at just the right time. Read on . . . .

Getting to the Ground . . . . the details

1. The days get shorter and nights get longer. This causes a chemical in the tree called phytochrome to tell the tree slow down.

2. The leaf makes less and less food and green chlorophyll each day.

3. Special cells between the branch and the leaf stem (the abscission layer) begin to break down, making a weak spot on the stem.

4. The leaf is now only held onto the branch by the thread-like veins.

5. Wind and gravity break the leaf off at this weak spot.

6. The leaf floats to the ground. The branch forms a hard covering called a "leaf scar" to heal the spot where the leaf fell off. Look for these leaf scars next time you find a small twig.
What happens to leaves after they land on the ground?

Maple trees are excellent soil builders! The leaves are quickly eaten by insects, worms, and other small animals' in the soil. The animals waste (scat) is broken down further until it is ready for another trip up through the roots of another plant. Maples are know as better than average soil builders because the fall leaves tend to be full of nutrients like calcium, phosphorus, and magnesium.
Cool Facts
Phytochrome seems to work by sending a signal to the tree that the nights are longer, not that the days are shorter.
Evergreens loose leaves each year too, but they always keep the newer needles, so we don't notice the change as much as on deciduous trees.
The earthworms that help turn the fallen leaves back to soil are aliens! They were brought by people to Minnesota, Wisconsin, and North Dakota. See how earthworms change the soil.

Think About It!
  1. Why might leaves make good garden compost?
Explore the Web
See Wolf Ridge naturalist Kevin Zak's picture-a-day of the same Sugar Maple as it changed in the fall of 2002.
General information about trees.
Activity from "Journey North"
Learn more about trees in these Wolf Ridge classes:
You can take the Trees and Keys class at Wolf Ridge. During Trees and Keys class, you will travel through the trees and keys course, visit trees and see how many you can correctly identify. At the end of class, you will receive a tropical forest tree seed to plant to remind you of the value of maintaining biodiversity.
Explore the world of plants! Learn about how plants live and grow, why they are so different, and how they are alike. How do plants and animals help each other? Depending on the season, you might also make foods, drinks, perfumes, or dyes from the plants you find. More about our Plant Study class.
Hike away from the main Wolf Ridge campus through the woods and across the boardwalks to our Forestry Building outpost. You'll pack a lunch and be gone for the day. During the Forest Ecology class, you'll hike through a variety of managed forests, getting a chance to do some forest management along the way, beginning with a try at an old-time cross cut saw, and ending by taking on the role of a forest, wildlife, recreation, or water management specialist.
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