The two are just barely linked. Now.. to be completely accurate, there is a change in stall speed with CG change, but it's so small that I doubt you could detect it outside of a wind tunnel. What happens is.. As the CG changes forward the pitching moment of the wing increases, and more downforce is required to hold a given angle of attack. That change in downforce from the tail requires the wing to counteract the reduction in lift from the tail for level flight(yes, the tail does provide some lift), so yes, an increase in angle of attack is required. BUT, we're talking miniscule amounts here. For reference, a Cessna 172, at the most forward CG at 2400 pounds, compared to the most rearward CG allowed, changes the stall speed by 1 knot. One.