Enhancement of botanical diversity of permanent grassland and impact on hay production in Environmentally Sensitive Areas in the UK

Published source details Hopkins A., Pywell R.F., Peel S., Johnson R.H. & Bowling P.J. (1999) Enhancement of botanical diversity of permanent grassland and impact on hay production in Environmentally Sensitive Areas in the UK. Grass and Forage Science, 54, 163-173.
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This study is summarised as evidence for the following.

	Action	Category
	Remove topsoil or turf before seeding/planting Action Link
	Sow native grass and forbs Action Link
	Restore/create species-rich, semi-natural grassland Action Link

Remove topsoil or turf before seeding/planting

A replicated, randomized, paired, controlled study in 1994–1996 in six improved grassland sites in England and Wales, UK (Hopkins et al. 1999) found that removing turf before sowing seeds increased grass and forb species richness in most cases compared to disturbing soil before sowing. No statistical analyses were carried out in this study. In eight of 12 comparisons, there were more grass species in plots where turf was removed and seeds sown (10–15 species/plot) than in plots where soil was disturbed and seeds sown (4–13 species/plot). In the four other comparisons, the number of grass species was similar in plots that had turf removed or soil disturbed before sowing (both 7–12 species/plot). In 10 of 12 comparisons, there were more forb species in plots where turf had been removed and seeds sown (11–28 species/plot) than in plots where soil was disturbed and seeds sown (3–25 species/plot). In the two other comparisons, the number of forb species was similar in plots that had turf removed (10–12 species/plot) or soil disturbed (8–13 species/plot) before sowing. In 1994, at each site, twelve 6 x 4 m plots were mown. In four plots/site, turf was removed to a depth of 3 cm. In eight plots/site, soil was disturbed by harrowing (four plots) or rotovating (four plots). Seed mixes (five grass species and 18 forb species) were sown at a rate of 12–14 kg/ha in all plots in early August 1994. In May/June of 1995 and 1996, three 40 x 40 cm quadrats were placed in each plot and the frequency of each grass and forb species recorded.

(Summarised by: Philip Martin)
Sow native grass and forbs

A replicated, randomized, paired, controlled study in 1994–1996 at six improved grassland sites in the UK (Hopkins et al. 1999) found that sowing grass and forb seeds had mixed effects on grass and forb species richness. No statistical analyses were carried out in this study. In 13 of 24 comparisons, plots where seeds were sown had more grass species (5–12 species/plot) than plots where no seeds were sown (4–10 species/plot), while in 11 comparisons, grass species richness was lower or equal (seeded: 4–13 species/plot, unseeded: 5–13 species/plot). In 17 of 24 comparisons, forb species richness was higher in plots where seeds were sown (7–25 species/plot) than plots where no seeds were sown (5–15 species/plot) while it was lower or equal in seven of 24 comparisons (seeded: 3–8 species/plot; unseeded: 4–8 species/plot). In 1994, at each site, soil was disturbed and seeds sown in eight 6 x 4 m plots and four plots were left unseeded. Seed mixes contained seeds of five grass species and 18 forb species. In May/June of 1995 and 1996, three 40 x 40 cm quadrats were placed in each plot and the frequency of each species recorded.

(Summarised by: Philip Martin)
Restore/create species-rich, semi-natural grassland

A replicated, controlled trial on six Environmentally Sensitive Area sites in England and Wales, UK (Hopkins et al. 1999) found that sowing 35 to 40 plant species increased the number of broadleaved plant species on all sites relative to the control and the number of grass species increased on five of the six sites by the second year. The sowing treatments with the most soil disturbance; rotavating and de-turfing, established the most species. In year one, there was an average of seven broadleaved species and seven grass species on the control plots, compared to sixteen broadleaved species and ten grass species on the deturfed treatment, which had the strongest increase in species richness. The trial was carried out in 1994 on 6 x 4 m plots monitored for the following two years, with four replicates of each treatment on each farm. Seven species were successfully introduced by some or all treatments on all sites: yarrow Achillea millefolium, oxeye daisy Leucanthemum vulgare, self-heal Prunella vulgaris and ribwort plantain Plantago lanceolata, black knapweed Centaurea nigra, bird’s-foot trefoil Lotus corniculatus and cat’s ear Hypochoeris radicata. Other species, including yellow rattle Rhinanthus minor, failed to establish.