Elevated <scp> CO ₂ </scp> and enriched nitrogen proportionally decrease species richness most at small spatial scales in a grassland experiment

Abstract Global changes such as nitrogen (N) enrichment and elevated carbon dioxide (CO 2 ) are known to exacerbate biodiversity loss in grassland ecosystems. They do so by modifying processes whose strength may vary at different spatial scales. Yet, whether and how global changes impact plant diversity at different spatial scales remains elusive. We collected data on species presence and cover at a high resolution in the third decade of a long‐term temperate grassland biodiversity—global change experiment. Based on the data, we constructed species—area relationships across three spatial orders of magnitude (from 0.01 to 3.24 m 2 ) and compared them for the different global change treatments. We found that N enrichment, both und