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Sediment samples were collected during four years from two plots, one covered by natural vegetation and the other, a “replica” of the same plot, from which the vegetation was removed manually (disturbed plot), in order to evaluate the effects of vegetal cover on sediment particle size distribution. Particle-size was measured using a Coulter LS130 laser diffraction device. The effective size distribution of the sediment was compared with equivalent measurements of the same samples after chemical and mechanical dispersion (ultimate size distribution) to investigate the detachment and transport mechanisms involved in sediment mobilisation. The ratio between the ultimate particle size composition of the transported sediment and that of the parent soil provided a measure of the particle-size selectivity of the transported sediment. The median effective particle was coarser than the median ultimate particle for almost all …