Land Molluscs and Their Environments in an Oligotrophic Area in Southern Sweden

Environmental factors influencing the occurrence of land molluscs (calcium, pH, moisture, vegetation) were studied in five types of woodland habitat, chosen in a CaCO3-free area. The necessary supply of Ca occurs in organic material, mainly in litter and foerna. Correlations between the Ca content in the foerna and abundance of snails were found and also between Ca and number of mollusc species. Different Ca salts dominate in the leaves of different tree species. The relatively high content of Ca oxalate at most oak wood localities has no direct pH increasing effect, while there is a pH increase in the soil surface at localities with ash, lime, maple and elm, probably depending upon the fact that in litter from these trees more soluble and therefore more alkaline Ca salts, e. g. Ca citrate, dominate. Forests containing the latter tree species often have rich mollusc faunas. Correlations between soil moisture and abundance of snails were also found. Pe3IoMe