Ant (Hymenoptera: Formicidae) communities in reclaimed and unreclaimed brown coal mining spoil dumps in the Czech Republic

Ant communities were investigated in brown coal mining spoil dumps, and in the surrounding landscape by hand collecting in 100 m2 quadrats, during spring 2001. Two transects of pitfall traps were also set up, from the base to the peak of spoil mounds (one each in forest and open habitats), and were sampled from May 1998 to May 2001 in order to investigate the composition of resident (workers) and colonizing (virgin queen) ants in the community. The overall numbers of species recorded on the dumps and in the surrounding landscape were comparable, which may result from both the higher number of sites sampled, as well as the higher diversity of sites in dump habitats. The dumps were mostly colonized by species common to the surrounding semi-natural habitats. However, two mountain species, absent from the surrounding landscape, Formica lemani and Manica rubida, were recorded on the dumps. Ant communities in forest plantations on spoil dumps were dominated by Myrmica rubra and Myrmica ruginodis. Lasius niger was locally abundant in the forest plantation and was the most common species of the non-forest dump habitats. Lasius flavus, Myrmica rubra, M. ruginodis and M. scabrinodis were common species in surrounding meadows but rare on the spoil. We postulate that the absence of Lasius flavus on spoil results from its low migration and colonization abilities. In the case of Myrmica rubra, its absence from open dumps probably resulted from environmental constrains of the habitat. The redundancy analysis (RDA) indicated two groups of factors critical for ant community composition. The first group (plot age, depth of humus and fermentation layers, cover of bare soil and soil substrate) corresponded to the successional age of the plot and to the development of the soil. The second group of parameters (tree cover and presence of Salix caprea shrubs) characterized a gradient between forests and open habitats.