11 research outputs found
Carabid beetle and spider assemblages along a forested urbanârural gradient in southern Finland
To investigate the effects of urbanization on carabid beetles (Carabidae) and ground dwelling spiders (Araneae)
a study was completed along a 20 kmurbanârural forest gradient in the HelsinkiâEspoo area of southern Finland. To
study changes in assemblage structure, abundance and species richness, these taxa were collected in the year 2000
using pitfall traps, which had been placed in four forest sites within each of the urban, suburban and rural zones.We
expected to find changes in the abundances and species richnesses in the two taxa across the urbanârural gradient,
but did not find any. Our second and third hypotheses, stating that generalist species and small-bodied species should
gain dominance along the gradient from rural to urban sites, were partly supported as carabid specialists were more
characteristic of suburban and rural environments whereas generalists were more likely to be collected from rural
areas compared to suburban or urban sites. Furthermore, medium to large-sized carabid individuals were more likely
to be collected in the rural sites compared to urban forests. We found no evidence for significant changes in spider
abundance or species richness across the urbanârural gradient in relation to body size or habitat specialization. We
suggest that urbanization does not have significant effects on the total abundances and species richnesses in these
two taxa. However, individual species responded differently to urbanization, and there were significant differences
in the specialization and body sizes of carabids across the gradient