Impact of the invasive moss Campylopus introflexus on carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) in acidic coastal dunes at the southern Baltic Sea

Abstract

Campylopus introflexus is an invasive moss in Europe and North America that is adapted to acidic and nutrient-poor sandy soils with sparse vegetation. In habitats like acidic coastal dunes (grey dunes) it can reach high densities, build dense carpets and modify habitat conditions. While the impact of the moss invasion on the vegetation is well analyzed, there is a lack of knowledge regarding possible effects on arthropods. In the present study we analyzed the impact of Campylopus introflexus on the grounddwelling arthropods carabid beetles and spiders, as both taxa are known to be useful indicator taxa even on a small-scale level. In 2009 we compared species composition in a) invaded, moss-rich (C. introflexus) and b) native, lichen-rich (Cladonia spp.) acidic coastal dunes by using pitfall traps. A total of 1,846 carabid beetles (39 species) and 2,682 spiders (66 species) were caught. Species richness of both taxa and activity densities of spiders were lower in invaded sites. Species assemblages of carabids and spiders differed clearly between the two habitat types and single species were displaced by the moss encroachment. Phytophagous carabid beetles, web-building spiders and wolf spiders were more abundant in native, lichen-rich sites. Shifts in species composition can be explained by differences in the vegetation structure, microclimate conditions and most likely a reduced food supply in invaded sites. By forming dense carpets and covering large areas, the moss invasion strongly alters typical arthropod assemblages of endangered and protected (EU-directive) acidic coastal dunes.

Response of carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) to coastal heathland succession

“…In addition, adequate food supply is very important, as is water resource (Müller-Motzfeld 2004). Both taxa contain highly specialized species which even react on small scale-habitat conditions (Schirmel et al 2010a). Often these xerothermic, specialized species are rare and endangered mainly due to the loss of suitable habitats (Müller-Motzfeld 2004;Buchholz 2008Buchholz , 2010.…”

“…Carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) are useful indicator taxa to analyze shifts in terrestrial ecosystem conditions (Rainio and Niemela 2003;Lambeets et al 2008;Schirmel et al 2010a). Especially the use of carabid beetles in ecological heathland studies has a long tradition in Europe (Gardner 1991;Usher and Thompson 1993).…”

In stable, unmanaged grasslands local factors are more important than landscape-level factors in shaping spider assemblages

“…34 Spiders are one of the most abundant and species rich 35 generalist predators. They contribute to the biodiversity in natural 36 and agricultural ecosystems (Wise, 1993 prey availability (Heikkinen and MacMahon, 2004;Horváth et al, 40 2005; Batáry et al, 2008;Schirmel et al, 2011 (Clough et al, 2005;Horváth et al, 2013;Schmidt et al, 2008). 44 Moreover, the human disturbance…”

Conservation management of coastal dunes for Orthoptera has to consider oviposition and nymphal preferences

“…That mosses can have a comparable relevance for oviposition in D. verrucivorus has so far been unknown. The higher air humidity above mosses (shown for C. introflexus in Schirmel et al 2011) and their ability for water storage might even favour egg development of D. verrucivorus. Ensifera, even xerothermic species, need generally more water for egg development than Acrididae (Ingrisch and Köhler 1998) and the need of a sufficient water supply for development was demonstrated for D. verrucivorus (Moriaty 1970;Ingrisch 1988).…”

“…As studies by Cherrill and Brown (1992) for chalk grassland and by Schuhmacher and Fartmann (2003) for acidic grassland showed young nymphs of D. verrucivorus are also associated with patches of bare ground or short turf. Although C. introflexus carpets are important egg-laying substrates and nymphal habitats we have to mention that the moss is an invasive species in Europe and North America having negative impacts on plant diversity and vegetation Sykora 2004, 2008;Hasse 2005Hasse , 2007 and on ground-dwelling arthropods (Schirmel 2011;Schirmel et al 2011).…”