The importance of coastal sand dunes for terrestrial invertebrates in Wales and the UK,with particular reference to aculeate Hymenoptera (bees,wasps &; ants)

Although most UK sand dune systems are now fossilized, with little mobility and reducing amounts of bare sand, they support important populations and assemblages of terrestrial invertebrates. Offering open conditions, warm substrates and a range of habitats and habitat structures, they have become increasingly significant as other coastal habitats have been lost. In Wales, 680 Red Data Book and Nationally Scarce species have been recorded from dunes. 109 species in the UK are restricted to dunes, and in Wales there are an additional 145 species confined to dunes and 208 species strongly associated with dunes. Of these, 172 species are dependent upon bare and sparsely-vegetated sand, in grey dunes and early-successional dune grassland, at some stage of their life cycle, rising to 292 species if those associated with the strandline, foredunes, yellow dunes and pioneer dune slacks are included, equating to 63% of the 462 dune species. Bees and wasps are particularly well represented, with 278 species (68% of the Welsh fauna) recorded on Welsh dunes, including 17 obligates and 44 species with a strong dependence, 52 of which are associated with bare and sparsely-vegetated sand. Key to maintaining invertebrate populations on UK dunes is the provision of bare sand but in Wales, bare sand accounts for only 1.7% of the total sand dune resource. As a more appropriate bare sand threshold is likely to range between 10 and 30%, radical action is required to re-mobilize at least the key sand dune systems.