Conservation ecology of land snails: a synthesis for Estonia

ABSTRACT We provide a synthesis of how the regional fauna of land snails, a flagship group among invertebrates, is distributed across ecosystems and how that translates to conservation priorities in Estonia. The data were compiled from 24 assemblage studies (mostly sample quadrats or substrate volume sampling; totalling >80,000 individuals) and from species records of infrequent species in the country since the 1970s. These data were quantitatively analysed for snail diversity and species frequencies by ecosystem types, and for the conservation status and indicator value of species. The known Estonian extant fauna contains 80 native and 12 presumably non-native species, of which 11 native species were assessed as threatened (2 not found in the 21st century). Hydrologically functional fens, old eutrophic forests, wooded meadows and calcareous areas appeared hotspots for threatened species and for overall snail diversity and abundance. As conservation measures, strict protection of natural forests and fens is fundamental, whereas the consequences of ecological restoration of alvars and fens require further study. Invasion of non-native species has greatly accelerated in the last 15 years, but it still mostly affects human settlements and their surroundings. We conclude that the Estonian land snail fauna is in a vulnerable state that largely depends on the integrity of hotspot ecosystems. There is a critical lack of knowledge on the value of small habitat patches and ecological restoration, and ecological responses to the snail invasions.