New tools to boost butterfly habitat quality in existing grass buffer strips

Restrict certain pesticides or other agricultural chemicals

A replicated, randomized, controlled study in 2008–2009 on two arable farms in Berkshire, UK (Blake et al. 2011) found that grass buffer strips which were not sprayed with grass-specific herbicide had a similar abundance and species richness of butterflies to sprayed strips. On unsprayed grass buffer strips, the abundance (3.7 individuals/plot), species richness (3.7 species/plot) and diversity of butterflies was not significantly different to strips which had been sprayed with herbicide (abundance: 2.2 individuals/plot; richness: 2.5 species/plot; diversity presented as model results). Six-metre-wide grass buffer strips were created on two arable farms in 2004 and managed under an Entry Level Stewardship agreement from 2005. In April 2008, three pairs of 25 × 4 m plots were established at each farm. One random plot/pair was sprayed with a grass-specific herbicide (“fluazifop-P-butyl”), and the other was left unsprayed. All plots were cut to 15 cm in autumn, and cuttings left in place. From May–September 2008–2009, butterflies were surveyed twice on each of four days/year on a 25-m transect through the centre of each plot.

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

Plant grass buffer strips/margins around arable or pasture fields

A replicated, randomized, controlled study in 2008–2009 on two arable farms in Berkshire, UK (Blake et al. 2011) found that sowing wildflowers in grass buffer strips which have been scarified and treated with grass-specific herbicide increased the abundance, diversity and species richness of butterflies. Butterfly species richness was higher in plots that had been scarified, sown with wildflower seeds and treated with grass-specific herbicide (5.8 species/plot) compared with single treatment plots (scarification and seeding: 2.6; herbicide: 2.5 species/plot) and plots with no scarification, seeding or herbicide (3.7 species/plot). Butterfly abundance (6.8 individuals/plot) and diversity were higher in plots that were scarified, seeded and treated with herbicide than single treatment plots (scarification and seeding: 2.5, herbicide: 2.2 individuals/plot), but similar to plots with no scarification, seeding or herbicide (3.7 individuals/plot; diversity presented as model results). Six-metre-wide grass buffer strips were created on two arable farms in 2004 and managed under an Entry Level Stewardship agreement from 2005. In spring 2008, three blocks of four 25 × 4 m plots were established at each farm. One of four treatments was applied randomly to each plot: scarification in March 2008; application of grass-specific herbicide (“fluazifop-P-butyl”) in April 2008; scarification and herbicide application; and no scarification or herbicide. Scarification was always followed by sowing a seed mixture of nine wildflower species. All plots were cut to 15 cm in autumn, and cuttings left in place. From May–September 2008–2009, butterflies were surveyed twice on each of four days/year on a 25-m transect through the centre of each plot.

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

Plant grass buffer strips/margins around arable or pasture fields

A replicated, controlled study in the summers of 2008-2009 in Berkshire, UK (Blake et al. 2011) found that butterfly (Lepidoptera) abundance, species richness and diversity were positively associated with the number of sown wildflower species in existing grass buffer strips. Butterfly species richness was higher in plots that had received a combined treatment of scarification and grass-specific herbicide application compared with single treatment and control plots. Butterfly abundance and diversity were higher in plots that were both scarified and treated with grass-specific herbicide than single treatment, but not control plots. Sown wildflower cover and species richness was higher in the combined treatment plots in both years, and there was a significant increase in wildflower cover from 2008 to 2009. In both years, species richness of unsown wildflowers (annuals, perennials and in total) was higher in the combined scarification/grass-specific herbicide treatments. It was also higher in scarification-only than in grass-specific herbicide-only and control plots, but it decreased in scarified plots from 2008 to 2009. Six metre-wide grass buffer strips were created on two arable farms in 2004 and managed under an Entry Level Stewardship agreement from 2005. Four treatments were randomly established within each of three replicate blocks/site in early spring 2008: scarification, selective grass-specific herbicide application, scarification and selective grass-specific herbicide, control. Scarification was always followed by sowing a wildflower seed mixture. All plots were cut in autumn and cuttings left in place. In both years vegetation was assessed once in June, in ten randomly placed 0.25 m² quadrats within each treatment plot avoiding the edges. Percentage cover of all plant species was estimated on an eight point scale. Abundance, diversity and species richness of adult butterflies was recorded during standard transect walks along the centre of each treatment plot (25 x 4 m). Each plot was sampled eight times/year between May and September.