Arthropod abundance and diversity in differently vegetated margins of arable fields

Field margin strips, sown with either the main field crop, rye grass ( Lolium perenne), a grass and wild flower mixture, or left to natural regeneration, were established in replicated plots along three hedgerows and field edges. Pitfall traps were used to assess the carabid beetle fauna in mid-summer between 1993 and 1996. Suction sampling was used to assess a wider range of arthropod taxa in June 1994. Pitfall data showed no significant overall effects from plot-type although significant differences in carabid activity-density were found between fields and years. In contrast, suction sampling showed marked differences between the crop, the hedge and the plots with different vegetation structures. There was a significant positive correlation between faunal and floral diversity, with arthropod diversity lowest in the crop, low in the crop edge, higher in the more diverse sown plots and highest in the hedge. Studies of over-wintering arthropods from soil samples revealed similar trends, confirming that arthropods colonised sown margin strips within 11–15 months of establishment. The results indicate that the appropriate scale for using pitfall traps is at the field rather than the plot scale. The introduction of botanically diverse field margin strips is shown to be an important method of increasing the arthropod diversity of semi-natural habitat in farmland.