The ant fauna of Central and Eastern European countries is relatively well studied. In Romania the first checklist was published in 1978 containing 76 species (Paraschivescu 1978). From the middle of the ‘90ies myrmecological investigations were renewed (eg MARKÓ 1999ac, CSŐSZ & al. 2001, MARKÓ & CSŐSZ 2002), and these resulted in an updated checklist of the Romanian myrmecofauna (MARKÓ & al. 2006). Upon this checklist and other recent publications (Markó 2008a, b) the Romanian fauna currently contains 105 ant species, which is, however, considerably less then the fauna of other neighbouring countries (see Markó & al. 2006 for an exhaustive comparison). Most of the Romanian myrmecological studies deal with the myrmecofauna of a wider region (eg Paraschivescu 1961, 1976, Cîrdei & Bulimar 1965, Markó 1997, 1999a), and only few studies focus on the myrmecofauna of restricted areas (eg Paraschivescu 1982, Csősz & al. 2001, Markó 2008a), or carry out structural analysis in order to reveal interspecific mechanisms standing at the base of ant community organization (Markó 1999b, Markó & al. 2004). As ants are widely used as indicator group (see Agosti & al. 2000 for a review) comprehensive checklists of small areas constitute good starting points for local nature protection activities. Ultimately the knowledge of qualitative-quantitative composition of the local fauna and the distribution of species among different habitat types can serve as basis for future complex studies treating the relationship between local and regional biodiversity patterns (Agosti & al. 2000).

The ant fauna of Sibiu County is one of the most well-known in Romania (Markó & Csősz 2002, Csősz & Markó 2005), nevertheless even in this case there is a need for complete faunistic datasets on specific areas as the currently available data are mostly scattered as origin. In the frame of this study we focus on specific areas in Sibiu County, in the vicinity of Sibiu city and compare the structure of ant communities in two different habitat types: grassland and forest.