The effects on butterfly abundance of the management of uncropped edges of arable fields

Restrict certain pesticides or other agricultural chemicals

A replicated, randomized, site comparison study in 1989–1991 in Oxfordshire, UK (Feber et al. 1996, same experimental set-up as Feber et al. 1994) found that butterfly abundance and species richness were higher on naturally regenerated field margins that were not sprayed with herbicide than on margins which were sprayed once a year. After one year of herbicide application, both the abundance (39 individuals/50 m) and species richness (8 species/50 m) of butterflies were higher on uncut margins which were not sprayed than on uncut sprayed margins (abundance: 18 individuals/50 m; richness: 6 species/50 m). After two years of herbicide application, there were more butterflies on both cut and uncut margins which were not sprayed (abundance: 17–37 individuals/50 m; richness: 8–9 individuals/50 m) than on uncut sprayed margins (abundance: 12 individuals/50 m; richness: 7 species/50 m). In the first year of herbicide application, there was no difference between unsprayed (abundance: 15–44 individuals/50 m; richness: 6–9 species/50 m) and sprayed margins (abundance: 42 individuals/50 m; richness: 6 species/50 m). Two-metre-wide field margins around arable fields were rotovated in October 1987 and left to naturally regenerate. Fifty-metre-long plots were either uncut and unsprayed, subject to one of four different cutting regimes but unsprayed, or uncut but sprayed once a year with herbicide (glyphosate, 3 l/ha Roundup^TM in 175 l water) in late June or early July 1989–1991. There were eight replicates of each treatment. Butterflies were monitored weekly from June–September 1989 and from April–September 1990 and 1991.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Plant nectar flower mixture/wildflower strips

A replicated, randomized, site comparison study in 1987–1991 in Oxfordshire, UK (Feber et al. 1996, same experimental set-up as Feber et al. 1994, Feber & Smith 1995) found that butterfly abundance and species richness were higher in sown wildflower margins than in unsown, naturally generated margins. From two years after establishment, both individual abundance (21–91 individuals/50 m) and species richness (7–10 species/50 m) of butterflies were higher in sown wildflower margins than in unsown margins (abundance: 14–39 individuals/50 m; richness: 6–9 species/50 m). Additionally, in all three years, sown margins had more butterflies if they were left uncut (abundance: 49–91 individuals/50 m; richness: 9–10 species/50 m), or were cut in spring and autumn (abundance: 27–88 individuals/50 m; richness: 7–9 species/50 m), than if they were cut in summer (abundance: 21–46 individuals/50 m; richness: 7–10 species/50 m). In autumn 1987, two-metre-wide field margins around arable fields were rotovated. In April 1988, half were sown with a seed mixture (3 kg/ha) containing six grasses and 17 non-woody broadleaved plants (forbs). The rest were left to regenerate naturally. Within each sown and unsown margin, 50-m-long plots were managed in one of four ways, with eight replicates of each treatment: uncut; cut once in June; cut April and June; cut in April and September. Hay was collected after cutting. Butterflies were monitored weekly from June–September 1989 and from April–September 1990 and 1991.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Create uncultivated margins around intensive arable or pasture fields

A replicated, randomized, site comparison study in 1987–1991 in Oxfordshire, UK (Feber et al. 1996, same experimental set-up as Feber et al. 1994, Feber & Smith 1995) found that butterfly abundance and species richness were lower in unsown field margins than in margins sown with wild grasses and non-woody broadleaved plants (forbs), and that margin management affected butterfly numbers. From two years after establishment, both individual abundance (14–39 individuals/50 m) and species richness (6–9 species/50 m) of butterflies were lower in unsown, naturally regenerating margins than in sown margins (abundance: 21–91 individuals/50 m; richness: 7–10 species/50 m). However, in all three years, unsown margins had more butterflies if they were left uncut (abundance: 28–40 individuals/50 m; richness: 8–9 species/50 m), or were cut in spring and autumn (abundance: 29–44 individuals/50 m; richness: 8–9 species/50 m), than if they were cut in summer (abundance: 14–27 individuals/50 m; richness: 6–8 species/50 m). In autumn 1987, two-metre-wide field margins around arable fields were rotovated. In April 1988, they were either left to naturally regenerate or sown with a wildflower seed mix. Within each unsown and sown margin, 50-m-long plots were managed in one of four ways, with eight replicates of each treatment: uncut; cut once in June; cut April and June; cut in April and September. Hay was collected after cutting. Butterflies were monitored weekly from June–September 1989 and from April–September 1990 and 1991.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Create uncultivated margins around intensive arable or pasture fields

A randomized, replicated study from 1989 to 1991 in Oxfordshire, UK (Feber et al. 1996) (same study as Feber et al. 1994) found that butterfly (Lepidoptera) abundance and species richness was lower in unsown, naturally generated margins (14-39 individuals, 6-9 species) than in sown wildflower margins (21-91 individuals, 7-10 species) from the second year after establishment. Spraying with herbicides (Roundup^TM) and cutting during summer reduced butterfly diversity and density in the margins, but there were no such effects of cutting in spring and autumn. Both cutting in summer and spraying led to an immediate decline in the number of flowering plants directly after the treatment. In the cut margins, however, the number of flowers had increased by September when it was higher than in uncut margins. Butterflies were monitored weekly along transects from June to September 1989 and from April to September 1990 and 1991. Transects were divided into 50 m sections corresponding to the experimental plots. Monitoring was done according to standard methods and only under suitable conditions. This study was part of the same experimental set-up as Feber et al.1994, Baines et al. 1998, Bell et al. 1999, Haughton et al. 1999, Smith et al. 2010).

Plant nectar flower mixture/wildflower strips

A randomized, replicated study from 1989 to 1991 on the Oxford University Farm, Oxfordshire, UK (Feber et al. 1996) found that butterfly (Lepidoptera) abundance and species richness were higher in sown wildflower margins (21-91 individuals, 7-10 species) than in unsown, naturally generated margins (14-39 ind., 6-9 spp.) from the second year after establishment. Cutting during summer reduced butterfly diversity and density in the margins, but there were no such effects of cutting in spring and autumn. Cutting in summer also led to an immediate decline in the number of flowering plants directly after the treatment. However, the number of flowers in cut margins had increased by September when it was higher than in uncut margins. Existing field margins (0.5 m-wide) were extended by 1.5 m in October 1987. The extended margins were rotavated and either left to naturally regenerate or sown with a wildflower seed mix in March 1988. Fifty-metre-long plots were managed in one of the following ways: uncut, cut once in summer hay collected, cut spring and summer hay collected, cut spring and autumn hay collected, cut spring and summer hay left lying (unsown margins only), sprayed once a year in summer (unsown margins only). There were eight replicates of each treatment. Butterflies were monitored weekly along transects from June to September 1989 and from April to September 1990 and 1991. Transects were divided into 50 m sections corresponding to the experimental plots. This study was part of the same experimental set-up as Feber et al. 1994, Baines et al. 1998, Bell et al. 1999, Haughton et al. 1999, Smith et al. 1999, Bell et al. 2002, Smith et al. 2010.