European Mountain Plant Losses Rise Amid Species Gains

A study in Science finds that Europe’s mountain summits are gaining plant species overall as warming allows lower-elevation plants to move upslope, but this apparent biodiversity increase masks accelerating local extinctions. Researchers analyzed 896 permanent vegetation plots on 62 summits across 16 mountain regions, surveyed four times from 2001 to 2022 through the GLORIA monitoring network. Species adapted to cold, high-elevation environments disappeared more often, with losses greatest on summits that experienced the strongest warming. Researchers say rising temperatures may contribute directly through reduced water availability and shorter snow cover, while newly arrived plants may also outcompete established alpine specialists. Because many alpine plants decline for years before disappearing, the study suggests current losses may reflect an accumulated “extinction debt” and warns that higher species counts do not necessarily indicate healthier mountain ecosystems.