Stand in the woods in the fall for any length of time and you are sure to see a leaf fall from a tree.  In fact, you will  see lots of leaves fall.  In many back yards, people rake the leaves into piles, put them into bags and throw them out with the trash.  But for all of you people who let them lie where they fell, what happens to them?  Well, as you probably know, they decay.  This, of course, means that they are eaten by insects, fungi, bacteria and a whole host of other organisms.  But do you know which types of leaves decay the fastest?  Or what conditions are best for leaf decay?  Here is an easy to do experiment that will furnish you with some of the answers.

Materials:

•a few boards – size is not important, but a 3/4 inch thick board about 12 inches long by 4 inches wide will do nicely

•a staple gun

•leaves from different trees.  If possible, find leaves that are still green and in good condition

Directions:

1.Collect a number of leaves from the different types of trees in your back yard.

2.Try to make sure the leaves are all about the same size and in the same condition.  This makes comparing them at the end of the experiment easier.

3.Divide the leaves up into sets – one of each type of leaf in a set.  For instance, in each set have one maple leaf, one oak leaf, one aspen leaf and so on.

4.Staple one set of leaves onto a board – side by side but not touching.  Do this for as many sets as you want to test.

5.In your Nature Journal, record which leaves you put on the board and the date you put them there.

6.Choose different habitats to place each set of leaves.  By placing them in different habitats you can see which conditions cause leaves to decay faster.  You might want to place one set in the deep forest where they are always in the shade.  Another might be placed under a pile of leaves where it is constantly moist.  A third set might be placed out in the open where it gets a lot of sun.  A fourth set might be placed submerged in a stream or pond.  Record the locations and conditions in your journal.

7.Check your leaf sets after a week.  Do the leaves look different than they did at the start of the experiment?  Have they been chewed on?  Do you notice any sign of decay?  Record your observations.

8. Replace the leaves in their original spots.  Then check them again in a week. Continue to check them every week until they have completely decayed.  And continue to record your observations

Did one type of leaf decay slower than the others throughout all of your habitats?  If so, why do you think this was?  Many trees have chemicals in their leaves that are distasteful to insects. Perhaps these chemicals also are distasteful to the organisms that are causing the leaf decay. Next summer, check the leaves of the trees from your experiment.  Does the insect damage you see on the trees correlate with the leaf decay rates you saw in your experiment?

What conditions did you find were most favorable to leaf decay?  Did they decay faster in a moist or dry environment?  Did the amount of sunlight they received make any difference?  What other factors may have influenced leaf decay?  Can you make an assumption why certain conditions caused the most rapid leaf decay?  Can you come up with an experiment to test your assumption?