On 5 Mar 1997, Anne Heise wrote:
> I think I heard (maybe on this listserv?) that WD Hamilton hypothesizes
> that oaks keep their leaves as some sort of signal to aphids -- saying
> don't settle here. Does this ring a bell w/ anyone?
>> Anne Heise
> Washtenaw Community College
> Ann Arbor MI
Anne,
That message was in the "why do leaves turn color in the fall" thread.
Hamilton and a student hypothesized that trees that are able to turn red
will do so more intensely after a season in which they have stored lots of
energy and could mount a more vigorous defense in the spring... I don't
have access to the reference but one could search the archives using
"Hamilton aphids" and pull up the message...
While I'm here, I recall a hypothesis I heard long ago regarding the leaf
retention question. As I learned it, oaks retain leaves near the trunk
of the tree over the winter to shade the trunk thus reducing the repeated
thawing/freezing that could cause damage. I looked in my books today and
found nothing on this topic. Has anyone seen any studies on this?
Jon
