The data set comprises vegetation species and abundance information, surveyed using a 50 x 50 cm point quadrat, from a selection of the plots within an experimental site at Sourhope, Scotland. The surveys were carried out in the summers of 1998, 1999, 2000, 2001 and 2002. The data were collected as part of the NERC Soil Biodiversity Thematic Programme, established in 1999 and centred upon the intensive study of a large field experiment located at the Macaulay Land Use Research Institute (now the James Hutton Institute) farm at Sourhope in the Scottish Borders (Grid reference: NT8545019630). During the experiment, the site was monitored to assess changes in above-ground biomass production (productivity), species composition and relative abundance (diversity). Full details about this dataset can be found at https://doi.org/10.5285/c730867f-ffd7-4d2d-9dd0-e2f30a7dbbf6