THE FORMATION OF SPRINGTAIL ASSEMBLAGES (HEXAPODA, COLLEMBOLA) ALONG A RETREATING TSEY GLACIER, NORTH OSSETIA – ALANIA

Abstract

Successional changes in springtail communities were studied along a retreating Tsey Glacier at 2336 to 2071 m a.s.l. Springtails were collected from 10 sites of different ages ranging from 1 to 170 years. The sites covered the main stages of surface overgrowth, from a bare ground through a grassy-shrub stage to mixed and then mature pine forests. Springtails appeared already during the first year after the glacier’s retreat and were represented by a species of the genus Desoria, a peculiar inhabitant of bare rocky-sandy soils. 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 later ones. Starting with this intermediate stage, springtail assemblages were primarily composed of widespread generalists belonging to euedaphic and hemiedaphic life forms. Beginning from this point, the pace of succession gradually slowed down. Approximately 100 years since, springtail communities reached a level of diversity similar to that found in mature mountain forest communities in the region. However, their species composition and structure remained quite distinctive. A comparison with similar foreign studies showed the composition of periglacial springtail communities to exhibit high-level regional specificity.