A dataset of the observations of cover of plant species over a temperate grassland in Inner Mongolia (2015–2020)

Field plots were established in July 2014 following a randomized block design. There were four treatments: control (ambient N condition), and NH4+–N/NO3––N at 5:1 (mixtures of NH4Cl and NH4NO3), 1:1 (NH4NO3) and 1:5 (mixtures of NH4NO3 and Ca(NO3)2∙4H2O) at 10 g N m–2 year–1. Each treatment had eight replicates, and each experimental plot was 4 m × 4 m. In 2015, each 4 m × 4 m plot was divided into 16 1 m × 1 m quadrats, and the four central 1 m × 1 m quadrats were assigned to permanent quadrats. The dataset consist of the coverages of each plant species and the plant community in each 1 m2 quadrate.