Exploring land snails’ response to habitat characteristics and their potential as bioindicators of riparian forest quality

Riparian ecosystems are crucial for landscape-level biodiversity, especially in highly anthropic and agricultural areas. Although the low mobility of snails reduces their dispersal capacity and makes them vulnerable to habitat degradation, they are less commonly used as indicators. We evaluated the potential of land snails as bioindicators of riparian forest quality in central European riparian forests by surveying snail communities in relation to habitat characteristics that characterize its quality. Habitat characteristics were found to affect both snail abundance and species richness. The abundance of snail species increased with the forest continuity, forest width and abundance of leaf litter and decreased with the cover of ruderal plant species and presence of household waste deposits. Snail diversity was positively influenced by habitat continuity, forest width, and abundance of dead wood. The community composition was also sensitive to habitat characteristics, most species having their optimum in habitats with high amounts of decaying dead wood and litter. Many species responded positively to habitat continuity, demonstrating that fragmentation is the main factor affecting abundance of land snail communities. Both total abundance of land snail communities and species richness were good predictors of habitat quality, snail abundance being more powerful than diversity. Aegopinella epipedostoma, Perforatella bidentata, and Helix pomatia were best at discriminating among high and poor quality forest habitats among individual species. Our study showed that among the parameters describing habitat quality, spatial and temporal continuity of riparian forest are the main factors affecting snail communities. Habitat fragmentation and the absence of suitable microhabitats for snail species preferring decaying wood lead to lower abundance and diversity of land snail communities confirming the potential of land snails as bioindicators of riparian forest quality