Rapid Change and Thermophilization of Summit Plant Communities in the Central Eastern Alps (Italy)

Aim Alpine vegetation is highly sensitive to global warming, as these ecosystems are shaped by cold temperatures. Upward migration of thermophilic species increases species richness at high elevations but may threaten cryophilic specialists. We assessed temporal changes in species richness, species turnover, and key drivers of vegetation change across summits, with a focus on potential tipping points in the nival belt. Location Four siliceous summits ranging from 2180 to 3287 m a.s.l. in the Texel Group (South Tyrol, Italy). Methods Vegetation and soil temperature data from 21 years (2003–2024) were analyzed using generalized linear mixed‐effects models (GLMMs) to assess shifts in species composition, ecological indicator values, and elevational distribution patterns. Results An ongoing increase in species richness (overall +13%) and thermophilization was observed on all summits except the subnival one, with a significant decline only in the southern slope of the lowest summit. A rapid increase in richness on the highest summit over the past 7 years (+75%) coincided with a longer growing season and higher mean soil temperatures. Colonization happened mostly in the eastern aspect, where soil temperature was highest. Main Conclusions New findings reveal that the nival belt, previously stable in species numbers, is now undergoing rapid vegetation change and provides the first evidence of thermophilization in the nival belt of the Central Alps. This might respond to the overcoming of a mean soil temperature of 4.9°C during the growing season, an ecological threshold associated with closed grasslands. In parallel to upward shifts of some species, cryophilic specialists face increasing habitat loss and fragmentation. Cooler northern aspects may act as short‐term microrefugia, but long‐term persistence will depend on the interplay between colonization, facilitation, extinction, and the availability of refuges in a rapidly changing alpine environment.