The Formation of Springtail Assemblages (Hexapoda, Collembola) along the Retreating Tsey Glacier, North Ossetia–Alania

Successional changes in springtail communities from ten sites of different ages ranging from one to 170 years were studied along the retreating Tsey Glacier at 2336 to 2071 m a.s.l. The sites covered the main stages of surface overgrowth, from bare ground through a grassy–shrub stage to mixed and then mature pine forests. It was shown that the springtails of the genus Desoria, a unique inhabitant of bare rocky–sandy soils, appeared already during the first year after the retreat of the glacier. During the first 7–14 years of succession, rapid changes in population and species composition repeatedly occurred. Both abundance and species diversity of springtails sharply increased at the grassy–shrub stage (14 years) and reached their maximum at the latest stages. Beginning from this point, springtail assemblages were primarily composed of widespread generalists belonging to euedaphic and hemiedaphic life forms and the succession gradually slowed down. After approximately 100 years, springtail communities reached a level of diversity similar to that found in mature mountain forest communities in the region, although their species composition and structure remained quite distinctive. A comparison with similar foreign studies showed that the composition of proglacial springtail communities exhibits high-level regional specificity.