  We examine the combined effects of winds and photoionizing radiation from
O--type stars on embedded stellar clusters formed in model turbulent molecular
clouds covering a range of masses and radii. We find that feedback is able to
increase the quantities of dense gas present, but decreases the rate and
efficiency of the conversion of gas to stars relative to control simulations in
which feedback is absent. Star formation in these calculations often proceeds
at a rate substantially slower than the freefall rate in the dense gas. This
decoupling is due to the weakening of, and expulsion of gas from, the deepest
parts of the clouds' potential wells where most of the star formation occurs in
the control simulations. This results in large fractions of the stellar
populations in the feedback simulation becoming dissociated from dense gas.
However, where star formation \emph{does} occur in both control and feedback
simulations, it does so in dense gas, so the correlation between star formation
activity and dense gas is preserved. The overall dynamical effects of feedback
on the \emph{clusters} are minimal, with only small fraction of stars becoming
unbound, despite large quantities of gas being expelled from some clouds. This
owes to the settling of the stars into virialised and stellar--dominated
configurations before the onset of feedback. By contrast, the effects of
feedback on the observable properties of the clusters -- their U--, B-- and
V--band magnitudes -- are strong and sudden. The timescales on which the
clusters become visible and unobscured are short compared with the timescales
which the clouds are actually destroyed.
