Abstract:The land mollusc faunas of three forest areas of Tuscany (central Italy) were sampled to test the effect of geographical and environmental factors on the structure of biodiversity. A total of 60 sites were surveyed in the years 2009-2011, recording species richness and abundance of snails in 400 m 2 plots randomly selected in beech and oak woods. Sampling strategy relied on a combination of visual search and litter analysis. Environmental variables (topsoil pH and altitude) and UTM coordinates were recorded to detect relationships with species richness and number of individuals per plot. Abundance data were analyzed using non-metric multidimensional scaling and canonical correspondence analysis; faunal similarity within and between areas was computed by the Bray Curtis index and snail assemblages of the two forest types were compared. A total of 55 species were recorded, with low values of local richness and abundance per site compared to other forest sites in central and northern Europe. Total richness was similar in the three areas, but composition and local richness varied significantly between them. Geographical factors explained the highest percentage of variance, while habitat type, altitude and pH only accounted for a minor part. Internal similarity was greater than between-area similarity in two out of three areas. Beech forests had richer and more heterogeneous faunas, but lower levels of abundance than oak woods. The results are discussed in terms of historical biogeography and local environmental conditions, and compared with those from similar surveys across Europe.
Nomenclature for snails: Manganelli et al. (1995).Abbreviations: AM -Monte Amiata; AP -Alpi Apuane-Garfagnana; CA -Casentino-Alta Valle del Tevere.
148Benocci et al.particularly sensitive to climate change effects, especially increased temperatures, modified rainfall patterns and soil properties (Resco de Dios et al. 2007), factors that can negatively affect the local survival of snails (Pearce and Paustian 2013); thus, describing their biocoenoses can provide valuable insights in monitoring and prevention programs, especially in protected areas. Ecological factors that shape terrestrial snail assemblages have been investigated in central and northern Europe for decades, focusing on single or combinations of environmental parameters (Valovirta 1968, Evans 1972, Martin and Sommer 2004, Horsák 2006, Kappes et al. 2006, Sulikowska-Drozd and Horsák 2007 but such studies are almost completely lacking for Italian land snails (Giusti et al. 2005), except for a paper on acid woodland in the southern Alps (Bishop 1980).Here we report a survey of snail assemblages in three forest areas of Tuscany (Figure 1b), carried out in two habitat types to test the effect of geographical and environmental factors on the structure of biodiversity: such questions have never been addressed before in Italy. Another innovative aspect of this research concerns the selection of plots: in previous studies focused on biodiversity patterns of European land snai...