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The relative impacts of nutrient availability, disturbance intensity, and interspecific competition on species distribution and growth were studied by applying five levels of nutrients and five intensities of clipping to simple artificial communities (of Dactylis glomerata, Holcus lanatus, Lolium perenne, and Trifolium repens) in a factorial design for 16 mo. This was done to test the hypothesis that the effects of interspecific competition would decline along gradients as the amount of nutrients decreased and the degree of disturbance increased. Nutrients and disturbance, alone and in interaction, produced significant effects on percent cover of all species, and all species achieved maximum percent cover in the undisturbed regime. The experimental design permitted us to distinguish between percent cover reductions caused directly by nutrients and disturbance from those caused by interspecific competition. When grown in …