In this paper we
investigate the relationship between the Hardy space Hq(R) of harmonic
functions on a hyperbolic Riemann surface R, and the Hardy space Pq(R) of
solutions of the equation Δu = Pu, where P ≧ 0, P≢0 is a C1-density on R.
Under certain conditions these spaces are shown to be canonically isomorphic,
although in general this is not the case. However, specific subspaces are found
which are isomorphic and their relationship with other function spaces is
discussed.