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Habitat choice in the carpathian land snails macrogastra tumida (Rossmässler, 1836) and vestia turgida (Rossmässler, 1836) (Gastropoda: Clausiliidae)
Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha Str. 12/16, 90-237 Lodz, Poland
Correspondence: e-mail: sulik{at}biol.uni.lodz.pl
The aim of the study was to elucidate on the basis of physical, floristic and edaphic features of habitat, the distribution in natural montane forests of the two endemic Carpathian clausiliid species, Macrogastra tumida and Vestia turgida. Sites sampled were in the Bieszczady National Park, East Carpathians, Poland. Snails were sampled quantitatively at 11 sites located along an elevation gradient in various floristic communities. The estimated population densities varied from 0 to 49 /m2 of forest floor. In a multivariate analysis, the first four axes accounted for 82.7% of variation in recorded environmental variation. The first axis, representing habitat fertility, correlated most strongly with the density of M. tumida. Density of V. turgida showed a weaker correlation with this axis, as it was relatively less abundant in the wettest sites, which were also the most fertile. Multiple regression models were used to determine the effects of single variables: plant species number, herb cover, slope aspect and habitat humidity were the best predictors of the snails' abundance at the sites. The interactions and intercorrelations of these factors are discussed in relation to land snail abundance.
(Received 21 January 2004; accepted 14 July 2004)