Andy,
To tell the truth no one knows about decline of land snails in the eastern
US.  Habitat destruction runs rampant as we all know, but land snails can
hold on to a tenuous existence in small parcels of even non-pristine
conditions.  Obviously, some are more sensitive than others, but they seem
to be holding their own.  There are so few land snail nuts and so much
territory to cover, we simply don't have enough data to make any
predictions, dire or otherwise.

Kurt