Land-snail diversity in a square kilometre of Cretan maquis: Modest species richness, high density and local homogeneity

The land mollusc fauna of 1 km2 of Cretan maquis was surveyed by sampling fourteen 400-m2 plots in May 2001, and by resampling six of these in February 2002. Sampling methods were designed to resemble those used in similar surveys of 1-km2 sites in tropical rainforests in Cameroon and Sabah. A total of 27 species were recorded for the site. Slugs and a semi-slug were found only in the 2002 survey. Individual plots were very similar in species richness and composition; the richest plot contained about 85% of the fauna recorded for the whole site. Overall densities were very high. This local homogeneity contrasts with marked heterogeneity over Crete as a whole. These results are contrasted with those from tropical forests, where individual plots vary considerably in richness and composition, where densities are lower and where the total site faunas are larger. Although there are problems associated with differing amounts of sampling error between studies, this contrast is striking and some possible causes are discussed. Further work in tropical forest on limestone may elucidate this.