The conservation value of sandy highway verges for arthropods - implications for management

Sandy highway verges in the Veluwe region can be of importance to light demanding, pioneer grassland and heathland communities, characteristic of nutrient-poor sandy soils. The last decade however, the open character of these road verges is negatively influenced by encroaching trees and shrubs. The responsible authorities are now considering restoring the open and low vegetation. Although ample knowledge exists about the botanical aspects, information on the importance of these road verges for arthropod species and the management needed is insufficient. We surveyed reference sites in these verges, especially for ground beetles, ants and spiders, and found many specialized, rare, protected, and red list species. It is apparent that management changes are required, and the reference sites are to be taken as the target situation for the rest of the verges. We formulated a set of management recommendations focused on arthropods. We advise to restore open situations in highway verges by removing trees and shrubs. The nutrientpoor zone with mosaics of low vegetation types should be maximized. If applied along the overall length, verges can potentially become suitable habitat corridors connecting different nature reserves. When large scale removal of the top soil is performed, high quality vegetation refugia should be left intact as a source from which arthropods can spread again. Subsequent management should consist of fine scale and phased mowing and removal of encroachment; yearly a fraction of the verges should be managed so that in approximately ten years time all sites have been managed and the cycle can be repeated.