Holographic gratings are recorded in LiNbO3: Fe using frequency-doubled pulses of aQ-switched Nd : YAG laser (light wavelengthλ = 532 nm, pulse durationtp = 20ns). We monitor diffraction efficiencies of the holograms during and several milliseconds after exposure. Variations of Fe2+ concentration, light intensity, and fringe spacing show that different types of gratings are involved: photochromic, thermooptic, pyroelectric, and space-charge gratings. The influence of the internal pyroelectric field on the light-induced charge transport is discussed in terms of a two-center model. Pyroelectric and bulk photovoltaic effect are shown to partially compensate each other. In LiNbO3: Fe, the photovoltaic effect is the dominant charge-driving force for our recording conditions.