A century of change: Many losers vs. few winners among Swiss grassland plants

Grasslands in Europe are important habitats for a significant portion of the continent's biodiversity yet have undergone substantial transformations due to land use and climate changes during the 20th century. As plant species have been differentially impacted by these alterations, conservation efforts must not only consider overall species diversity but also assess changes at the individual species level. We resurveyed vegetation plots recorded in Switzerland between 1884 and 1931, covering a wide range of grassland types and elevations (300–2500 m a.s.l.), to identify plant species that have either increased or decreased in frequency and those that have experienced elevational shifts. Our findings reveal a predominance of decreasing species (losers) compared to increasing species (winners), with this pattern weakening at higher elevations. Notably, declines affected both rare and common species, the latter often being overlooked in conservation strategies. Decreases were most frequently associated with geophytes and species adapted to low nutrient conditions and cooler temperatures. While the proportion of neophytes increased at the expense of indigenous species and archaeophytes, it remained low overall. The upward shifts in mean elevation of many species appeared to be primarily driven by intensified land use at lower elevations, whereas climate change was likely a more significant factor at higher elevations, where human influence is less intense. The results underscore the need for enhanced conservation measures to preserve and restore grassland habitats, limit eutrophication (especially at lower elevations), and take action against climate change to allow mountain regions to function as refugia for some species. • Since 1900, many more grassland species have decreased than increased in frequency. • The strongest decreases occurred for moderately frequent to frequent species. • “Losers” were adapted to lower nutrient status and temperatures than “winners”. • The proportion of neophytes increased but remained low overall. • The upward shift of many species was more driven by land use than by temperature.