2011). Europe has a major share in only one of these hotspots, the Mediterranean Basin (cf. Hewitt 2011). This region is characterised by long-term isolation of the biota, which is often restricted to one of the various island

and peninsulas, AZD1080 mw which are separated by sea and/or hardly surmountable mountain barriers (e.g. the Alps, Pyrenees, Carpathians). Long-term isolation accompanied by relatively constant climatic conditions has led to the accumulation of species in southern Europe over the past millions of years, while temperate and northern Europe are characterised by 3-MA ic50 biodiversity impoverishment in consequence of the glaciation cycles with subsequent range retraction-expansion dynamics of species including extinction processes (Thompson 2005; Schmitt 2007; Habel et al. 2009). While being relatively species-poor AZD1152 in vivo at larger spatial scales, temperate Europe comprises certain habitats with extreme species richness at small scales, in particular the semi-natural grasslands. Recently, it has been shown that European semi-dry basiphilous grasslands exceed any other ecosystem

of the world including tropical rainforests with regard to vascular plant species richness for grain sizes <100 m² (Dengler et al. 2012; Wilson et al. 2012). Among Europe’s endemic vascular plants, 18.1 % are bound to grassland habitats, nearly twice as many as in forests, despite the latter

covering much more land area (Hobohm and Bruchmann 2009). Also, for many other taxa, the semi-natural grasslands host many more species than expected from their spatial extent, for example more than two-thirds of the butterflies (WallisDeVries and van Swaay 2009). While grasslands constitute the natural vegetation of the steppe biome in Eastern Europe (Bohn et al. 2004), they largely result from the activities of humans and their livestock (e.g. grazing, mowing, burning) in areas actually humid enough to allow tree growth (Ellenberg and Leuschner 2010; Vrahnakis et al. in press). Thus grasslands became widely distributed over Europe since the Anthropocene (Poschlod and WallisDeVries 2002; Poschlod et al. 2009; Hájková et al. 2011). During millennia of low-intensity land use, grasslands accumulated a Ixazomib order huge amount of biodiversity. Today, many of the European grassland ecosystems of high conservation value are threatened by a change of the very land use that formerly created and maintained them, i.e. intensification, abandonment, afforestation, or transformation of arable fields (WallisDeVries et al. 2002; Öckinger et al. 2006; Veen et al. 2009; Valkó et al. 2012). Further sources of threat include eutrophication through airborne nitrogen deposition, and in some cases biotic invasions. While these phenomena are well-known issues (e.g. Janišová et al.