Wood in contact with slightly humid concrete can easily develop dry rot. (search keyword "rot" for the title "WHAT IS DRY ROT?") This often happens to studs laid on the basement floor or standing up against basement walls. A perfectly dry basement will present no problem -- but how many basements do you know that are always perfectly dry?
Dry rot in the studs can be prevented by:
-- Using green, pressure-treated lumber, especially for the 2 x 4 that sits on the basement floor. 
-- Isolating the wood from the concrete with a plastic sheet or  strip.  A plastic sheet used to moisture-proof walls will serve the  purpose.  (search keyword "damp proof" for the title "DO I NEED TO  MOISTURE PROOF THE BASEMENT WALL BEFORE INSULATING?")  Or, you can  staple plastic strips around the back side of all studs, preventing  moisture from moving directly from the concrete into the stud.  If your  stud wall does not touch the concrete wall you only have to worry about  the wood in contact with the floor.
