Enhancing floral resources for pollinators in productive agricultural grasslands

Published source details Woodcock B.A., Savage J., Bullock J.M., Nowakowski M., Orr R., Tallowin J.R.B. & Pywell R.F. (2014) Enhancing floral resources for pollinators in productive agricultural grasslands. Biological Conservation, 171, 44-51.
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This study is summarised as evidence for the following.

	Action	Category
	Reduce cutting frequency on grassland Action Link
	Restore arable land to permanent grassland Action Link
	Reduce grazing intensity on grassland by seasonal removal of livestock Action Link

Reduce cutting frequency on grassland

A replicated, randomized, paired, controlled study in 2008–2012 on a farm in Berkshire, UK (Woodcock et al. 2014) found that grasslands established with flowering plants which were cut once/year had a greater abundance and species richness of pollinators (including butterflies) than grasslands cut twice/year. When sown with a seed mix including legumes or legumes and other non-woody, broadleaved plants (forbs), plots cut once/year had a higher abundance (8–91 individuals/plot) and species richness (3–8 species/plot) of pollinators than plots cut twice/year (abundance: 6–52 individuals/plot; richness: 3–6 species/plot). In plots sown with grasses alone, pollinator abundance (0–3 individuals/plot) and species richness (0–2 species/plot) were lower regardless of cutting frequency. In spring 2008, forty-eight 875-m² plots were sown with one of three seed mixes: a “grass only” mix of five species (30 kg/ha, cost: €83/ha); a “grass and legume” mix of five grasses and seven agricultural legumes (34 kg/ha, €120/ha); or a “grass, legume and forb” mix of five grasses, seven legumes and six non-legume forbs (33.5 kg/ha, €190/ha). Half of the plots were cut to 10 cm once/year in May, and half were cut to 10 cm twice/year in May and August. In May, July and August 2009–2012, butterflies, bees (Apidae) and hoverflies (Syrphidae) were surveyed three times/year on two parallel 20 × 2 m transects/plot.

(Summarised by: Andrew Bladon)
Restore arable land to permanent grassland

A replicated, randomized, paired, controlled study in 2008–2012 on a farm in Berkshire, UK (Woodcock et al. 2014) found that grasslands established with seed mixes containing legumes and other non-woody, broadleaved plants (forbs) had a higher abundance and species richness of pollinators (including butterflies) than grasslands sown only with grasses. Plots sown with a mix of grasses, legumes and forbs had a higher abundance (9–70 individuals/plot) and species richness (3–7 species/plot) of pollinators over four years than plots sown with grasses only (abundance: 0–3 individuals/plot; richness: 0–2 species/plot). In the first year after establishment, plots sown with grasses and legumes but no forbs had the highest abundance (15–91 individuals/plot) and species richness (5–8 species/plot) of pollinators, but this decreased over time (fourth-year abundance: 3–8 individuals/plot; richness: 2–3 species/plot). Grass and legume plots managed by cutting had a higher abundance (6–91 individuals/plot) and species richness (3–8 species/plot) of pollinators than plots managed by grazing (abundance: 3–33 individuals/plot; richness: 2–5 species/plot). Management had less effect on other seed mixes. In spring 2008, ninety-six 875-m² plots were sown with one of three seed mixes: a “grass only” mix of five species (30 kg/ha, cost: €83/ha); a “grass and legume” mix of five grasses and seven agricultural legumes (34 kg/ha, €120/ha); or a “grass, legume and forb” mix of five grasses, seven legumes and six non-legume forbs (33.5 kg/ha, €190/ha). Half of the plots were grazed with cattle (3 animals/ha) and half were cut to 10 cm once or twice/year. In May, July and August 2009–2012, butterflies, bees (Apidae) and hoverflies (Syrphidae) were surveyed three times/year on two parallel 20 × 2 m transects/plot.

(Summarised by: Andrew Bladon)
Reduce grazing intensity on grassland by seasonal removal of livestock

A replicated, randomized, paired, controlled study in 2008–2012 on a farm in Berkshire, UK (Woodcock et al. 2014) found that grasslands established with flowering plants where cattle were removed for part of the summer had a greater abundance and species richness of pollinators (including butterflies) than grasslands grazed throughout summer. When sown with a seed mix including legumes or legumes and other non-woody, broadleaved plants (forbs), plots where cows were removed in the summer had a higher abundance (8–56 individuals/plot) and species richness (3–6 species/plot) than plots where cattle grazed throughout the summer (abundance: 3–49 individuals/plot; richness: 2–7 species/plot). In plots sown with grasses alone, pollinator abundance (0–3 individuals/plot) and species richness (0–2 species/plot) were lower regardless of grazing intensity. In spring 2008, forty-eight 875-m² plots were sown with one of three seed mixes: a “grass only” mix of five species (30 kg/ha, cost: €83/ha); a “grass and legume” mix of five grasses and seven agricultural legumes (34 kg/ha, €120/ha); or a “grass, legume and forb” mix of five grasses, seven legumes and six non-legume forbs (33.5 kg/ha, €190/ha). Half of the plots were lightly grazed (3 cows/ha, May and September–October) and half were more heavily grazed (3 cows/ha, May–October). In May, July and August 2009–2012, butterflies, bees (Apidae) and hoverflies (Syrphidae) were surveyed three times/year on two parallel 20 × 2 m transects/plot.

(Summarised by: Andrew Bladon)