Primary immigration and succession of soil organisms on reclaimed opencast coal mining areas in eastern Germany

Immigration to and colonisation of recultivated opencast coal mining areas by soil organisms were investigated in eastern Germany during the period 1996–1998 in freshly exposed substrates (immigration test) and two up to 46-year-old afforested mine soils (stage-dependent succession). The results indicate that immigration by air is characteristic for protists, soil microarthropods and spiders, while active locomotion is more important for the soil macrofauna. Testate amoebae assemblages showed no evident differences between 30–37-year-old Tertiary afforestations (ash-ameliorated, pyrite-rich, low soil pH) and 46-year-old Pleistocene sites (liming, low pyrite content, moderate soil pH), while comparisons in soil animals revealed pronounced differences in abundance, biomass and species composition. Earthworms, for example, reached a mean biomass up to 108 g m–2 in the Pleistocene deciduous afforestation. The Tertiary site had only 7–12 g m–2. Generally, all investigated soil animal groups indicated taxon-specific immigration and colonisation strategies with pronounced site preferences, dependent on substrate quality, age and afforestation. Within 40 years, a consistent trend is visible from an open pioneer to a woodland community. Furthermore, it was demonstrated that long-term investigations as well as numerous taxa of different trophic levels are essential for a comprehensive evaluation of recultivated mine dumps.