Mowing in agri-environmental schemes (AES) and rare species of Vertigo snails: hope for grasslands but a threat to snails

Abstract

Four Vertigo species are covered by special forms of protection under Annex II of the Habitats Directive. The habitats of these snails are currently rare in Europe. Since typical conservation practices are ineffective for this ecosystem, support mechanisms for measures maintaining biodiversity have been incorporated into agriculture in the form of agri-environmental schemes (AES). However, an inappropriately designed AES may threaten the survival of populations of globally endangered species such as Vertigo moulinsiana (Dupuy) as mowing and swath removal dates coincide with the snails’ activity period in the upper parts of the mown plants, the majority of their population will be removed from the area along with the harvested swath. In addition, mowing instantaneously and radically alters the habitat’s microclimate. The policy of mowing the total area thus leads to unprecedented habitat homogenisation across the landscape, especially when machine mowers are used. In the case of V. moulinsiana, the best approach would be not to mow the whole area but to leave a part unmown where these snails could live unhindered. Instead of machines, traditional mowing could be implemented, which entails cutting at a greater height above the sedge clump level. This would not destroy the tussock structure and would allow the habitat to recreate itself. In combination with the designation of unmown refuges, the effects of this approach could be quite beneficial to the snails.