Agriculture Ecosystems 4% Enwonment Agriculture,Ecosystems and Environment 53 ( 1995) 123-135 Foraging activity of bumblebees zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML (Bombus) in relation to flower resources on arable land W. Dramstad”,“, G. Fryb ‘Department of Biology and Nature Conservation, PO Box 5014, Agricultural University of Norway, N-1432 AAS, Norway bNorwegian Institutefor Nature Research, PO Box 5064, Agricultural University of Norway, N-1432 AAS, Norway Accepted3 1 August 1994 Abstract Increasing interest in combining agricultural and nature conservation goals has focused on the potential beneficial role of remnant biotopes on farmland. This study examines the role of field boundaries and a small habitat island within cereal fields in providing a source of forage for bumblebees (Bombus Latr.), throughout one season. Transect techniques were used to assess bumblebee use of common types of boundary vegetation between crops and semi-natural habitats, and along a footpath within a small woodlot, in southeastern Norway. There were seven species of bumblebee in these habitats, which used only a small fraction of the total number of flowering plant species available to any extent; only nine out of a total of 78 flowering plant species received more than five visits. All bumblebee species had a preference for perennial herbs as forage resources. The quantity of floral resources, their spatial pattern and temporal constancy varied among sites with the least disturbed and open habitats being of greatest value to bumblebees. Length of field boundary and single date surveys are poor indices of the value of field boundaries to bumblebees. Keywords: Bumblebees;Farmland; Foraging; Field margins; Floral resources 1. Introduction During the period from 1960 to 1990, loss of remnant biotopes as a result of agricultural intensification were a major concern for conservation organizations throughout Europe (Green, 1986). During the 1990s there has been a greater emphasis on combining the goals of conservation and agriculture (Firbank et al., 1991; Dennis and Fry, 1992; Saunders et al., 1992). In lowland Norway, a matrix of non-crop habitats exists between crop fields and forests. These areas are char- acterized by a cover of semi-natural vegetation har- bouring a high diversity of plants and animals (Fry, *Corresponding author. 1991). In intensive cereal growing areas more than 90% of flowering plant species are confined to these remnant biotopes. There is a substantial literature on the value of bum- blebees as pollinators of crops, e.g. red clover (Trifol- iumprutense zyxwvutsrqponmlkjihgfedcbaZYXWVUT L.) , field bean ( Viciufaba L.) and alfalfa (M edicago sutim L.) (Free, 1970). Less information is available on their importance as pollinators of wild flowers, although some recent studies have focused on the role of bumblebees in maintaining populations of rare plants in small, fragmented populations (Kwak et al., 1991; Petanidou et al., 1991). Nevertheless, it is well established that they possess morphological and ecological features which allow them to fill pollination niches which cannot efficiently be replaced by honey- 0167~8809/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDlO167-8809(94)00561-3