Grasslands with calcareous gyttja soil in the Olsztyn Lake District as specific habitats for ground beetles (Coleoptera: Carabidae)

The aim of the present paper was to determine the species composition and structure of carabid beetle assemblages found in carbonate-rich soils. The sites chosen for analyses lie on the bottom of a former ribbon lake that used to connect two lakes. The study was carried out in Northeastern Poland near Olsztyn in 2013. Two areas (with two sites distinguished in mentioned areas) were selected for the observations: an extensively used meadow and the agricultural wetland being transformed to bog. A total of 1573 individuals, representing 39 species, were captured in pitfall traps. The results reveal that grasslands located on carbonate soils, especially those excluded from agricultural use, are a source of valuable and rare species of Carabidae and such kind of sites should be subject to special monitoring. Furthermore it was found that factors which most probably differentiated the species composition of carabid beetles on calcareous grasslands were: different land use, changeable moisture conditions and the presence of forests in the surrounding of the habitats.