Tree Leaf Science Activities

Did you do the tree leaf age experiment last spring to see how long tree leaves stay on the tree? Now would be a good time to check your trees. Let us know what you found out so far. Some of the leaves we marked on our orange tree last spring are still on the tree.

If you live where trees are deciduous, you might want to study the next step:  what happens to leaves when they fall off the tree?

First, think about and make a list of what you think might happen. Do you think some might be eaten, or that they will all blow away?

Scientists study the decomposition, or breakdown of leaves, by putting leaves in nylon mesh bags and letting them sit on the ground for long periods of time. The researchers come back every few weeks and pick up a few bags to take back to the laboratory. They open the leaf bags up and see what is happening. They look at things like how much weight the leaves lost, what kinds of critters have been eating the leaves, and how the leaves have lost chemicals (nutrients) over time.

You can make your own leaf bags (also called litter bags).

Gather:

  • Heavy duty screen door nylon mesh (1 x 2 mm mesh size is best) or the nylon mesh bags that fruits or onions come in from the grocery store.
  • Equipment, such as scissors, for cutting screen mesh
  • Equipment for closing the screen bag: glue gun or sewing needle and thread (soldiering irons can be used by adults).
  • Place you can safely leave leaf bags under trees and be able to retrieve them over time

If you are using the pre-made nylon bags from the grocery store, you can skip this step. If you are using screen door mesh, cut out strips 10 inches (25 cm) wide and cut into 8 inches (20 cm) sections and fold in half. Use the glue gun, needle and thread or soldiering iron to seal two sides. Leave one end open so you can put the leaves in.

Once you have the leaf bags made, go outside and fill them with leaves. Try to use freshly fallen leaves and collect only the leaves from under the trees where you will be leaving your bags. If the leaves are too dry, you can wet them with a bit of water to get them into the bags without crumbling. The grocery store bags will have larger openings, so you might want to use bigger leaves.

Close the bags with hot melt glue, or by sewing or tying them shut. Place the leaf bags outside in a place where you can safely retrieve them. You might consider marking the bags with sticks in the ground or tying the bags to brightly colored tent pegs shoved into the ground.

Now you have to be patient. Check the bags roughly every month and see how they are faring. Leave them under the trees until next year and then be sure to collect them. Open the bags into a tray or pan and sort through the contents. What do you think you might find?

For a scientific discussion of the procedures for studying leaf decomposition, check this Sewanee Leaf Litter Decomposition Manual.

Other fun activities for fall leaf drop season are to put the leaves back on the tree and exploring fall color.

Do you know what kind of tree this is?

We’d love to hear what you find in your leaf bags.

Edit: I just found three awesome ideas for using fall leaves at 5 Orange Potatoes. The first is laminating leaves to make leaf rubbing plates. The second is a game called odd leaf out. The third is making polka dot leaves.

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