This dataset uses data from the NutNet dataset to examine the factors controlling how initially dominant species decay in dominance through time. We use data from all sites that had NPK and/or fencing treatments and pre-treatment when data was downloaded in 2021; 90 sites in all were used. Perturbations were NPK treatments (nitrogen, phosphorus, potassium and micronutrients) and fencing (vertebrate herbivore exclusion). Dominance was quantified as the rank percentile of a species in each year. Rank percentiles range from 1 (most abundant) to 0 (absent), with decimal values indicating relative rank - e.g. a species with rank 0.6 is more abundant than 60% of co-occurring species. Thus, only species with a rank of 1 in year o (pre-treatment) are included in this dataset. Covariates for examining rates of dominance decay include plot level initial and yearly cover values, both absolute and relativized; species provenance, lifespan, and functional group; site level climate variables and site richness.