The GLOBENET project in Sofia was expanded from studies on carabid beetles to assess how diff erent soil invertebrates refl ect urbanisation. Carabid beetles, terrestrial gastropods and ants were chosen for being well-studied, widely distributed and functionally important groups in ecosystems. At the same time, they are characterised by diff erent life strategies, habitat requirements and trophic relationships.
The urban faunas of all three groups were formed by (1) filtering out several native species from the regional species pools of Sofi a Kettle, (2) gaining new autochtonous species, and (3) gaining new allochtonous species. The latter is exhibited mainly by gastropods and less by ants (invasive ant species are found only in houses or greeneries). There were also no clearly invasive carabid beetle species. A trend of colonisation by invasive gastropods species from Sofi a invading the surroundings was observed.
In all three groups, there were clearly distinguishable “urban” assemblages that differed from those of the rural and suburban zones. Specific suburban assemblages were formed by ants, but not by gastropods or carabid beetles. The main factors aff ecting spatial variation of ground-beetle, ant and terrestrial gastropod assemblages respectively were: distance from the city center; perimeter/area ratio of the fragment, area of the homogenous habitat, distance to the nearest fragment; and altitude, area and level of urbanisation of the sampling sites.
The patterns of urbanisation had much in common amongst the three groups studied, but at the same time they displayed group-specifi c peculiarities. Hence, bioindication and monitoring activities should be carefully planned to include various taxonomic groups with diff erent life-strategies.
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