Relationships between terrestrial gastropod distribution and soil properties in Galicia (NW Spain)

Abstract

This study investigated the influence of edaphic factors on the distribution of 17 terrestrial gastropod species over a large area of the northwest Iberian Peninsula. A total of 498 gastropod/soil samples were obtained, and a total of 19 edaphic variables determined. The resulting data matrix was analysed by detrended canonical correspondence analysis (DCCA). Our results indicate that the gastropods of the study area can be grouped on two types of criteria: first, chemical criteria (notably pH, cation exchange capacity, and Al content), and secondly physical criteria (notably texture and moisture content). In view of distribution with respect to these factors, two well-defined groups can be identified: one comprising Acanthinula aculeata, Euconulus fulvus, Punctum pygmaeum, Columella aspera and Oxychilus alliarius preferring coarse-textured acid soils, the other comprising Cochlicopa lubrica, Vertigo pygmaea, Zonitoides excavatus, Carychium tridentatum, Deroceras reticulatum and Deroceras lombricoides preferring wetter, finer-textured, less acid soils. Arion intermedius and Ponentina subvirescens were in general indifferent to the edaphic factors considered.