[Ecoed] food web diagrams

[Christopher Picone]

Howdy:

I think confusion arises when we do not clarify whether the food web diagram illustrates energy flow OR population regulation.  Identical diagrams are used for either lesson.  If the point is to demonstrate energy flow (as is emphasized in K-12), then the arrows should go from producer to consumer, prey to predator, etc.  But if the diagram is meant to illustrate population regulation, the arrows should go either direction, depending which forces are to be emphsized by the diagram.  If top-down, the arrows go from predator to prey; If bottom-up, the arrows go from prey to predator.

Cheers, 
Chris Picone


-----Original Message-----
From: ecoed-bounces at ecoed.net on behalf of Kristen Lennon
Sent: Thu 3/15/2007 8:14 AM
To: ecoed at ecoed.net
Subject: [Ecoed] food web diagrams
 
Hi,

I have a very simple question regarding the structure of "typical" food
web diagrams that I would like you to weigh in on so that I can have a
consensus. I'm working at the K-12 level, specifically at the middle
school level at the moment, to give you some idea as to from where I'm
coming. My understanding is that the arrows in food web diagrams always
go from producer to consumer and  prey to predator; showing the flow of
food from one organism to another. In my work, I have found that
students (and even some of my colleagues) tend to think that the arrows
should be reversed. Before I dismiss that as incorrect, I need some of
you to weigh in. 

I appreciate your input. Feel free to respond to the list server or to
me directly.

Many thanks,
Kristen 

Kristen A. Lennon, Ph.D.
Research Associate
Project 2061
American Association for the Advancement of Science
1200 New York Ave., NW
Washington, DC 20005 USA


Tel:202-326-7032
E-mail: klennon at aaas.org
http://project2061.aaas.org
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