  In this paper we show how the covariant gauge invariant equations for the
evolution of scalar, vector and tensor perturbations for a generic
$f(R)$-gravity theory can be recast in order to exploit the power of dynamical
system methodology. In this way, recent results describing the dynamics of the
background FRW model can be easily combined with these equations to reveal
important details pertaining to the evolution of cosmological models in fourth
order gravity.
