Diversity and Biotic Homogenization of Urban Land-Snail Faunas in Relation to Habitat Types and Macroclimate in 32 Central European Cities

Abstract

The effects of non-native species invasions on community diversity and biotic homogenization have been described for various taxa in urban environments, but not for land snails. Here we relate the diversity of native and non-native land-snail urban faunas to urban habitat types and macroclimate, and analyse homogenization effects of non-native species across cities and within the main urban habitat types. Land-snail species were recorded in seven 1-ha plots in 32 cities of ten countries of Central Europe and Benelux (224 plots in total). Each plot represented one urban habitat type characterized by different management and a specific disturbance regime. For each plot, we obtained January, July and mean annual temperature and annual precipitation. Snail species were classified into either native or non-native. The effects of habitat type and macroclimate on the number of native and non-native species were analysed using generalized estimating equations; the homogenization effect of non-native species based on the Jaccard similarity index and homogenization index. We recorded 67 native and 20 non-native species. Besides being more numerous, native species also had much higher beta diversity than non-natives. There were significant differences between the studied habitat types in the numbers of native and non-native species, both of which decreased from less to heavily urbanized habitats. Macroclimate was more important for the number of non-native than native species; however in both cases the effect of climate on diversity was overridden by the effect of urban habitat type. This is the first study on urban land snails documenting that non-native land-snail species significantly contribute to homogenization among whole cities, but both the homogenization and diversification effects occur when individual habitat types are compared among cities. This indicates that the spread of non-native snail species may cause biotic homogenization, but it depends on scale and habitat type.

Ecological lands for conservation of vascular plant diversity in the urban environment

“…This process results in losses of species diversity at regional and continental scales (Olden et al 2004;McKinney 2006). This process was noted not only in floras, but also in faunas of urban areas (Horsák et al 2013;Aronson et al 2014). In cities, biotic homogenization goes faster than in other ecosystems, thus urban biotas are the most threatened by losses of distinguishing elements, i.e.…”

An invasion from Germany: Deroceras invadens (Pulmonata: Agriolimacidae) and other synanthropic slugs in the southwest corner of Poland

“…One possible anomaly was that D. reticulatum seemed often not as common in our ten towns as it is reported to be elsewhere (e.g., klAusnitzeR & hübneR 1989, Meng & bössneCk 1998, hoRsák et al 2013b. A speculative explanation is that the high population density of the large slug A. lusitanicus might have had an effect on D. reticulatum, since most published studies predate the arrival of this pest.…”

“…The puzzling exception is the abundance of A. fus cus in Stara Kamienica, whereas it was never found elsewhere. Matzke 1973, Meng & bössneCk 1998, hoRsák et al 2013b. Woodland is considered the normal habitat for A. fuscus, but this does not at all describe where we found it in Stara Kamienica.…”

Comparison of plant and snail diversity patterns in the White Carpathian Mts (Czech Republic) across forest and grassland habitats

“…In contrast, a negative response of the total snail species richness (composed predominantly of forest species) to the proportion of human-made habitats was connected with landscape opening and reduction of forests as suggested by a significant and negative correlation between proportion of forests and human-made habitats (r S = -0.79, Table 1). Furthermore, the pool of grassland snail species is generally small and only a limited number of snail species can tolerate unnatural and unstable conditions of highly anthropogenic habitats (Horsák et al 2013b).…”