THE BIODIVERSITY POTENTIAL OF RIPARIAN FIELD MARGINS IN INTENSIVELY MANAGED GRASSLANDS, pp. 357-362
Authors: L. J. Cole, D. I. McCracken, D. Robertson and W. Harrison, SAC, Auchincruive, Ayr, UK)
Abstract: Riparian field margins (i.e. fenced areas adjacent to watercourses) are becoming more widespread in intensively managed grassland systems in the UK as a means of mitigating diffuse pollution associated with intensive livestock farming. Invertebrate assemblages were examined in a range of riparian margins to determine their potential to deliver additional biodiversity goals. It was found that ground beetle assemblages in wide (> 4 m) margins were more distinct from the adjacent field than those in narrow margins ( 2 m) or riparian zones open to grazing. Furthermore, both wide and narrow riparian margins were found to enhance the abundance of several groups of invertebrates that are important prey items of farmland birds (i.e. leatherjackets, sawfly larvae and harvestmen). While fenced margins had higher abundances of bird prey items, the denser vegetation typical of such ungrazed margins may result in the prey being less accessible to foraging birds. Consequently routine management of such margins may be required to open up the vegetation structure and thus optimize their potential benefit to wildlife. Appropriately managed riparian margins have therefore the potential to increase biodiversity at the field level, by increasing the abundance of key invertebrates, and also at the landscape level, by increasing habitat heterogeneity and thus supporting distinct assemblages of ground beetles.