MadSci Network: General Biology
Query:

Re: What causes the tree leaves to fall in the Autumn ?

Date: Mon Nov 26 16:33:29 2001
Posted By: Cynthia Galloway, Faculty Biology
Area of science: General Biology
ID: 1005744099.Gb
Message:

Susie,

You seem to be asking two different questions here.  The first question, 
Why do plants lose their leaves in the fall?, generally can be answered by 
saying that the leaves are shut off from the food supply.  An abscision 
zone forms between the petiole and the stem cutting off the leaf from the 
plant.  There are many things that can affect leaf drop in plants.  Light, 
temperature, day length, and hormone concentration are all factors 
affecting leaf drop.  A website you might want to check out is listed 
below:
 ht
tp://www.nytimes.com/learning/students/scienceqa/archive/971118.html

Your second question is a little vague.  Are the big tree and little tree 
the same species?  Do they both receive the same amount of light?  Do they 
both have access to the same nutrients?  Some trees lose their leaves very 
rapidly while others lose them more slowly.  You need to make sure that 
both trees are the same species and are subjected to the same environmental 
conditions before you can answer this question.  You can still do your 
experiment by asking the question, Will this  big tree lose its leaves 
before the little tree?, and make a hypothesis.  You could hypothesize:

1) The big tree will lose its leaves first
2) The little tree will lose its leaves first
3) The trees will lose their leaves at the same time

Then, watch the trees to see how fast they lose their leaves to determine 
which hypotheses you  have disproved.


Current Queue | Current Queue for General Biology | General Biology archives

Try the links in the MadSci Library for more information on General Biology.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-2001. All rights reserved.