3 years back, I harvested a good amount of mature American chestnut seeds
from trees that had formed from an interesting circumstance.  In the
understory of a forest, little dormant chestnut saplings still exist.
 After a clearcutting timber harvest, these little saplings will suddenly
thrive with the full sunlight and no competition.  I found one of these
with a full seed mast.

I successfully germinated the chestnut seeds.  After growing them inside, I
transplanted the saplings throughout my yard.  Most of them have survived;
and have proven to be remarkably durable; 80% of them are still alive, and
doing their thing.

To find a mature 6-12+ inch tree in the forest is exceptionally rare.
Nonetheless, they do exist.      Could this be enough for the species to
survive without human intervention?  I don't think so...  The big
unaffected trees would have to be close enough to one another to get cross
pollinated by insects to get enough genetic diversity.  Then, the nuts
would have to avoid being eaten by the innumerable mammals, AND also
germinate; and also somehow outcompete the overstory.

Not to say it's impossible, but their chances are dramatically improved if
humans help.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html