  We present magnetohydrodynamic simulations aimed at studying the effect of
the magnetic suppression of turbulence (generated through various instabilities
during the formation of molecular clouds by converging) on the subsequent star
formation (SF) activity. We study four magnetically supercritical models with
magnetic field strengths $B= 0$, 1, 2, and 3 $\mu$G (corresponding to
mass--to--flux ratios of $\infty$, 4.76, 2.38, and 1.59 times the critical
value), with the magnetic field, initially being aligned with the flows. We
find that, for increasing magnetic field strength, the clouds formed tend to be
more massive, denser, less turbulent, and with higher SF activity. This causes
the onset of star formation activity in the non--magnetic or more weakly
magnetized cases to be delayed by a few Myr in comparison to the more strongly
magnetized cases. We attribute this behavior to the suppression of the
nonlinear thin shell instability (NTSI) by the magnetic field, previously found
by Heitsch and coworkers. This result is contrary to the standard notion that
the magnetic field provides support to the clouds, thus reducing their star
formation rate (SFR). However, our result is a completely nonlinear one, and
could not be foreseen from simple linear considerations.
