Vegetation relevés were carried out at five of the Terrestrial Environmental Observatories (TERENO) project (www.tereno.net) sites were mown or grazed grasslands were available. The initial study design was for investigating the impact of land management (mown meadows versus grazed pastures) on plant diversity and spatial scale heterogeneity. The selected grasslands were managed as either meadows or pastures for at least the last ten years. The initial study design was a balanced, nested design with three grasslands per land management type and study site. Vegetation relevés of 10 m x 10 m were established within identified grasslands from which 10 subplots, of 1 m^2, were randomly selected to be surveyed. Within each subplot all vascular plant species were determined and their cover was visually estimated to the nearest percentage as a proxy for abundance. Data is provided as percentage cover per subplot. Plant species names were updated according to The Plant List. Due to in-field limitations and more detailed records from farmers, the final data set consists of 270 subplot records, of which 120 are within meadows and 150 within pastures. The sampling inbalance should be accounted for (see associated publication for further details, and the supplementary plot combination file). Two complementary data sets were also collected at the same plots (with the same spatial resolution) for soil microbial diversity of fungi and bacteria. These data sets have been deposited in the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) under the accession PRJNA563995.