Land snail diversity can reflect degrees of anthropogenic disturbance

Abstract

Abstract. Faunal indicators of old-growth forests in heavily-disturbed regions are virtually non-existent.However, land snails, in particular micro-snails, could reflect the impact of land-use on ecosystem integrity. Because of their size, limited mobility, and propensity to spend their entire lives at one locality due to lack of migratory behavior, micro-snails are susceptible to changes in land-use within forested ecosystems. Therefore, we proposed the hypothesis that micro-snails would reflect land-use in forested ecosystems. We sampled snail communities in paired old-growth and second-growth forests in three distinct ecoregions. Species diversity, richness, and abundance were greater in two of the three old-growth sites compared to paired second-growth sites. Across all of the ecoregions, 21 out of 70 species had an affinity for old-growth. Eighteen of which were statistically significant. These results suggest that anthropogenic disturbance plays a key role in shaping species diversity and community structure of land snail fauna. However, site specific factors also appear to be important moderators of the response, and the mechanisms of the process remain to be studied. Snails appear to be a promising group of organisms to use as indicators of historic forest disturbance. In order to maintain ecological integrity, forest managers should consider management strategies that are low impact and protect existing patches of old-growth forests.

Land‐use in Europe affects land snail assemblages directly and indirectly by modulating abiotic and biotic drivers

“…Land snails are usually characterized by a low mobility and a non‐migratory behavior which make them vulnerable to changing environmental conditions (Baur and Baur , Douglas et al. ). Factors influencing snail abundances, snail diversity, and community composition in different habitats of different regions comprise abiotic parameters, differences in land‐use management, and biotic substrates.…”

“…, Horsák , Douglas et al. ), variation in land‐use intensity of different management types has been rarely studied. Results of our study indicate that direct effects (e.g., those that destroy shells by trampling or wood harvesting, those that destroy biotopes) of land‐use factors on snail densities, diversity, and community structure in forests and grasslands exist, but that they are of minor importance as compared to abiotic and biotic parameters.…”

“…Furthermore, anthropogenic land‐use in grasslands often changes open landscapes to fragmented habitats with a drier microclimate (Douglas et al. ). Moisture conditions may also be responsible for differences in community compositions among regions in our study since we found a high amount of freshwater species on several grassland plots in the Schorfheide.…”

“…Factors influencing snail abundances, snail diversity, and community composition in different habitats of different regions comprise abiotic parameters, differences in land-use management, and biotic substrates. While abiotic and biotic factors have been frequently linked to snail assemblages (Caldwell 1993, Martin and Sommer 2004a, b, Hylander et al 2005, Hors ak 2006, Douglas et al 2013, variation in land-use intensity of different management types has been rarely studied. Results of our study indicate that direct effects (e.g., those that destroy shells by trampling or wood harvesting, those that destroy biotopes) of land-use factors on snail densities, Notes: We included the abiotic factors soil moisture, soil pH, and precipitation; the land-use management factors mowing, grazing, and fertilization; and the biotic substrates number of grasses, herbs, and legumes.…”

“…Moisture conditions may also be responsible for differences in community compositions among regions in our study since we found a high amount of freshwater species on several grassland plots in the Schorfheide. Snail assemblages suffer from habitat fragmentation and desiccation since they depend on humidity and soil moisture which determine their time of feeding and breeding (Boycott 1934, Martin and Sommer 2004a, b, Hylander et al 2005, Douglas et al 2013, Hettenbergerov a et al 2013). Many snail species show a large moisture range, and land snail composition tightly responds to soil moisture (Martin and Sommer 2004b, Cejka and Hamerlik 2009, Hettenbergerov a et al 2013.…”