Land snails as indicators of soil humidity in Danubian woodland [SW Slovakia]

Moisture along with available calcium content are the major environmental factors controlling species richness and composition of the terrestrial molluscan fauna. In the present study, we focused on snails in a floodplain forest and their response on humidity. We described the model of response and calculate the humidity optima of particular species if possible. Generalised linear model (GLM) combined with Poisson distribution was used to ch aracterise the change of species abundance along a humidity gradient. From 31 species tested, 21 have shown significant response to humidity. The majority of specie s tested had unimodal response, four species showed monotonic regression type. Based on their humidity optima, species distributed along a moisture gradient belonged to three main ecological groups: (i) mesohygrophilous woodland species living mostly in non-inundated areas with humidity optima below 4, (ii) hygrophilous, forest hygrophilous and euryhygric species with optima between 4 and 6 and (iii) strongly hygrophilous (polyhygrophilous) species with mois ture optima above 6. Estimated moisture preferences for Danubian floodplain woodland land snail fauna would be a useful tool in a longterm biological monitoring of changing moisture regime.