The abundance of arthropods along two field margins with different types of vegetation composition: an experimental study

Abstract

The effects of vegetation types and reclamation measures on the abundance of certain functional groups of above-ground and soil arthropods (i.e. herbivores, predators and parasitoids) were studied. The study sites were a field margin totally dominated by couch grass, Elytrigia repens (L.) Nevski, a serious weed, and a field margin with a naturally diverse flora. The couch-grass dominated margin was in part ploughed and sown with leguminous plants, or left as fallow for natural succession of vegetation. The field margin with a naturally diverse flora harboured the highest abundance and diversity of all studied arthropod groups. However, couch grass, especially the dense vegetation and deep sod layer, appeared to be an important refuge for many groups, particularly predatory insects. Both the created leguminous and the weed-dominated natural successions were frequently visited by pollen- and nectar-feeding insects, while arthropods hibernating in the soil in late autumn were scarce. Except for the occurrence of blossom beetles associated with rape plants, the studied field margins were not found to harbour high numbers of any particular pest insect. The importance of field margins for faunal diversity in the agricultural landscape, and the possibility of improving the conditions for beneficial (predatory/ pollinating) arthropods are discussed.