Species and community dynamics on siliceous summits of the Texel Group, South Tyrol

Climate change will fundamentally affect the vegetation in high elevations. Via long term monitoring programs, substantial information can be obtained about the ongoing dynamics. The aim of the present study was to analyze diversity changes at four summits of the GLORIA target region Texel Group (South Tyrol, Northern Italy) from 2003 to 2017. Knowing that new colonization mainly occurs on the eastern and southern aspects of the Alpine summits, we compared the summit vegetation to the plant communities along the southern slopes of each summit from the treeline upward. We expected to gain information on potential migrators approaching the summits. We asked if cryophilic species disappear at the summits and if thermophilic species approach the summit area. With exception of the highest summit, an increase in species numbers throughout the years occurred. The newcomers at the lower summits were predominantly thermophilic species. Here, invasions of thermophilic species might limit cryophilic species in the near future. This process will be amplified due to increasing abundances of dwarf shrubs and trees. At the higher summits, where cryophilic species are still dominant, we assume that this species group will prevail for a longer time.