Abstract ID: 3.12121 | Accepted as Talk | Talk/Oral | TBA | TBA

In the alpine life zone, climate change already led to shift in the floristic composition as well as local species-specific changes in abundance. Environmental changes affected species’ distribution mostly resulting in shifts towards more warm- and nutrient-demanding plant assemblages. The study aims to assess plant species richness variations over time, species-specific abundance changes, biodiversity losses, floristic homogenization, and changes in the ecology of plant assemblages across vegetation belts located at different elevations within the alpine life zone. The study area includes 23 summits distributed over six mountain regions in the Italian Alps and the Apennines as part of the Italian GLORIA network, mostly monitored since 2001-2003. Changes in Alpha- and Beta-diversity were investigated through distinct metrics. Species-specific net-increases and -decreases (identifying “winners” and “losers” on the species level) in abundance were assessed by the Cliff’s Delta index. Shifts in the ecology of vascular plant assemblages were modelled over species pool abundance estimations weighted on Pignatti’s ecological indicators for the Italian flora. Species richness increased across most summits, except for three summits of the Apennines, where net species loss was observed. Species enrichment was higher in the upper and less densely vegetated areas. Floristic homogenization occurred at both mountain range and summit levels. Species evenness decreased at all vegetation belts, while increment in dominant species was more emphasized in the lower belts. Several gaining and losing species-specific trends were found in all regions, which overall led to significant shifts in the ecologic indicators. The study yielded a complex picture of the ongoing dynamics in the vascular plant assemblages monitored in the Italian GLORIA network. Species evaluated in the Alps’ sites proved to be generally more resistant showing less abundance reduction. The widespread homogenization observed suggests higher success for larger-range species, while overall diversity loss warns of increased threat to locally rarest species, which usually determine the alpine high floristic diversity. Moreover, the more frequent species-specific shifts of temperature, nutrient and humidity indicators observed in Northern and Central Apennines, compared to the Alps, suggests that plant species of mountain regions influenced by Mediterranean climate, respond more sensitively to climate change.