Vegetation is ubiquitous in riverine and coastal environments, but the physics governing morphodynamic interactions modulated by vegetation are still poorly understood. Here we use a simple experiment to study the impact of a vegetated patch on the morphodynamics of a sand bed. We show that the vegetation patch reduces the sediment transport capacity of the flow, and that the topography responds to this by an increase of the bed slope to accommodate the upstream sediment supply. Final bed slope and adjustment time scale depend on the ratio between the grain-related shear stress and the total shear stress. This demonstrates the mechanisms underlying a direct morphodynamic response to the presence of a vegetation patch.