The decays of intensity and anisotropy of UV-excited photoluminescence (PL) in hydrogenated amorphous carbon have been investigated in the ps-ns time range. For emission energies E-em between 1.8 and 3.5 eV, anisotropy decreases within 100 ps and reaches a plateau within 1 ns. The emission anisotropy plateau value increases (from 0.02 to 0.12) and the decay time of PL intensity decreases (from 1 ns to 40 ps) as E-em increases. The exponential increase of time-averaged anisotropy as E-em increases is explained by a competition between exciton decay and randomization of polarization due to electronic excitation energy transfer (Forster mechanism) between chromophores.