The response of bumblebees to successional change in newly created arable field margins

Published source details Carvell C., Meek W.R., Pywell R.F. & Nowakowski M. (2004) The response of bumblebees to successional change in newly created arable field margins. Biological Conservation, 118, 327-339.
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This study is summarised as evidence for the following.

	Action	Category
	Sow uncropped arable field margins with a native wild flower seed mix Action Link
	Leave arable field margins uncropped with natural regeneration Action Link
	Plant grass buffer strips/margins around arable or pasture fields Action Link
	Create uncultivated margins around intensive arable or pasture fields Action Link
	Plant nectar flower mixture/wildflower strips Action Link

Sow uncropped arable field margins with a native wild flower seed mix

In a replicated controlled three-year trial on three arable field margins at a farm in North Yorkshire, Carvell et al. (2004) found 6 m wide field margin plots sown, or half-sown with a native 'grass and wildflower' seed mix supported significantly more bumblebees than margins sown with tussocky grass, or control cropped field margins. The wildflower-sown margins supported significantly more bumblebees than naturally regenerated margins in the same experiment, in the first year of the study only, and this difference was not significant when data were averaged across all three years. However, the margins sown with wildflower seed mix supported consistently high numbers of bumblebees, whereas the naturally regenerated margins had one bumper year for bumblebees and were poor in the other two years.
Leave arable field margins uncropped with natural regeneration

In a replicated controlled trial on three arable field margins at one farm in North Yorkshire, Carvell et al. (2004) found 6 m wide naturally regenerated, uncultivated field margin plots supported significantly more foraging bumblebees than margins sown with tussocky grass, or control cropped field margins, but only in one year (2001) of this three year study. In the other two years (2000 and 2002), the naturally regenerated field margins did not support significantly more bumblebees than the control or grass-sown sites. In 2001, the bumblebees were mostly foraging on spear thistle Cirsium vulgare, a pernicious agricultural weed that had to be controlled by cutting at the end of that summer. Naturally regenerated margins were the only treatment that did not support consistent numbers of bumblebees in all three years.
Plant grass buffer strips/margins around arable or pasture fields

A replicated controlled trial in 2000-2002 in North Yorkshire, UK (Carvell et al. 2004) found 6 m-wide field margin plots sown with a ‘tussocky grass’ seed mix supported no more bumblebees Bombus spp. than conventionally cropped field margins. The study was carried out on three arable field margins of one farm. Each margin was split into five 72 m x 6 m plots and each plot subjected to one of five treatments: naturally regenerated, sown tussocky grass mix, sown grass and wildflower mix, split treatment of 3 m tussocky grass and 3 m grass and wildflower mix, or cropped to the edge. Bumblebee activity was surveyed using a standard ‘bee walk’ methodology. This study was carried out at the same experimental site as Telfer et al. 2000, Shore et al. 2005.
Create uncultivated margins around intensive arable or pasture fields

A replicated controlled trial from 1999 to 2002 on arable field margins in North Yorkshire, UK (Carvell et al. 2004) found 6 m-wide naturally regenerated, uncultivated field margin plots supported significantly more foraging bumblebees Bombus spp. than margins sown with tussocky grass, or control cropped field margins, but only in one year (2001) of this three year study. In 2001, the bumblebees were mostly foraging on spear thistle Cirsium vulgare, a pernicious agricultural weed that had to be controlled by cutting at the end of that summer. In the other two years (2000 and 2002), the naturally regenerated field margins did not support significantly more bumblebees than the control or grass-sown sites. Naturally regenerated margins were the only treatment that did not support consistent numbers of bumblebees in all three years. The naturally regenerated field margins supported fewer bumblebees (18 individuals and 2.7 species/100 m on average) than margins sown with a wild flower seed mixture (29 individuals, 3.0 species/100 m), but the two treatments were not directly compared in the analysis. Three cereal field margins on one farm were divided into five 72 m x 6 m long plots and subjected to five different treatments: natural regeneration (6 m wide), sown ‘tussocky’ grass mixture (6 m wide), sown ‘grass and wildflower’ mixture (6 m wide), split treatment of 3 m wide ‘tussocky’ grass mixture adjacent to hedge and 3 m wide sown ‘grass and wildflower’ mixture adjacent to crop, and margin cropped to the edge. Plots were cut and herbage removed following establishment of the seed mixtures. Wildflower plots were cut in August 2001 and 2002 and the herbage removed. Transects were walked along the central line of each plot recording bumblebee activity and identifying foraging bumblebees to species level.
Plant nectar flower mixture/wildflower strips

A replicated controlled trial in 2000-2002 in North Yorkshire, UK (Carvell et al. 2004) found that 6 m-wide field margin plots sown, or half-sown with a native ‘grass and wildflower’ seed mix supported significantly more bumblebees Bombus spp. than margins sown with a ‘tussocky grass’ mix, or control cropped field margins. Wildflower-sown margins supported significantly more bumblebees than naturally regenerated margins, but only in the first year of the three-year study, and this difference was not significant when data were averaged across all three years. Wildflower sown margins supported consistently high numbers of bumblebees, whereas naturally regenerated margins had one bumper year for bumblebees and were poor in the other two years. The three most popular forage plant species were cornflower Centaurea cyanus, bird’s-foot trefoil Lotus corniculatus and spear thistle Cirsium vulgare. The study was carried out on three arable field margins of one farm. Each margin was split into five 72 x 6 m plots and each plot subjected to one of five treatments: naturally regenerated, sown tussocky grass mix, sown grass and wildflower mix, split treatment of 3 m tussocky grass and 3 m grass and wildflower mix, or cropped to the edge. Bumblebee activity was surveyed using a standard ‘bee walk’ methodology.