Question
Several years ago I had a landscaper dump large amounts of 10-12 inch limestone rocks around my trees.  They are beginning to lose their "nuts" and leaves and it is only June.  Is this a result of the limestone?  Should I remove the limeston?

Answer
Limestone is actually a good thing in regard to pH balance & acid rain issues.  It also helps with heavy clay soils, but only if it is in powder form...

http://www.elmhurst.edu/~chm/vchembook/196soil.html

I don't know what kind of tree you have, and don't really know specifics as to individual species that may be effected by limestone.

I would suggest you consult a local arborist, and I look specifically for an ISA certified person, as opposed to your run-of-the-mill tree trimmer.  They have heightened knowledge of your specific tree or the soils in your area.

Finding an ISA Arborist:
http://www.isa-arbor.com/findArborist/findarborist.aspx

Good luck!  ~Marc