Restore or create species-rich, semi-natural grassland
Overall effectiveness category Awaiting assessment
Number of studies: 6
Background information and definitions
In marginal lands where agriculture ceases to be viable, traditionally managed pastures and hay meadows are frequently abandoned. This leads to an increase in scrub cover, changing the habitat from open grassland to early successional woodland. While this may encourage butterflies and moths which prefer more closed habitats (see “Abandon/fallow grassland to allow early succession”), it is detrimental to species which prefer open habitats. This intervention covers the restoration of species-rich, semi-natural grassland from abandoned pasture or hay meadows, by clearing scrub and/or reintroducing low intensity grazing or mowing management.
For studies on the restoration of grassland from former arable land, “Restore arable land to permanent grassland”. For studies on the restoration of species-rich grassland from intensively managed grassland, see “Reduce grazing intensity on grassland by reducing stocking density”, “Reduce grazing intensity on grassland by seasonal removal of livestock”, “Reduce cutting frequency on grassland” and “Reduce management intensity on permanent grasslands (several interventions at once)”. For studies on the maintenance of species-rich grassland, see “Maintain species-rich, semi-natural grassland”. For studies on grassland restoration outside of a farmland context, see “Habitat restoration and creation – Restore or create grassland/savannas”.
Supporting evidence from individual studies
A replicated, site comparison study in 1993–1994 in 16 alpine meadows in southern Switzerland (Schwarzwälder et al. 1997) found that restored meadows had a similar number of adult heath fritillary Mellicta athalia to old, abandoned meadows, and fewer adult males and caterpillars, but not females, than traditional hay meadows. The abundance of adult male heath fritillaries and caterpillars on restored meadows (males peak: 20–22 individuals/hour; caterpillars: 0–0.2 individuals/hour) was similar to old, abandoned meadows (males: 21 individuals/hour; no caterpillars), but less than traditionally managed hay meadows (males: 30 individuals/hour; caterpillars: 0.5–3.5 individuals/hour) and recently abandoned meadows (males: 40 individuals/hour; caterpillars: 4–8 individuals/hour). The number of females was not significantly different between meadows (restored: 7–14; old abandoned: 5; traditional: 5; recently abandoned: 14 individuals/hour). Marked butterflies were recorded moving between all habitat types. From 1992, two abandoned meadows were restored by annual mowing, and two were restored by mowing every 4–5 years. Five old, abandoned meadows had been unmanaged for >25 years, five traditional hay meadows were mown once/year in June or July, two recently abandoned meadows had been unmanaged for around six years. From June–July 1993–1994, adult butterflies were caught and marked for 45 minutes/meadow every other day. In 1994, each meadow was searched for three hours, spread over several days, to record solitary caterpillars.Study and other actions tested
A replicated, site comparison study in 1999–2000 in southwest Finland (Poyry et al. 2004, same experimental set-up as 3) found that species-rich grasslands restored with cattle grazing had a lower abundance and species richness of butterflies and day-flying moths than abandoned (unrestored) grassland. The abundance of butterflies and moths was lower in both restored (126 individuals) and continuously grazed pastures (126 individuals) than in abandoned, unrestored pastures (306 individuals). The number of species was also lower in restored pastures (22 species) than in abandoned pastures (33 species), but the number in continuously grazed pastures was intermediate (26 species). Butterflies and moths were monitored in 1999 or 2000 on 10 restored pastures where, after at least 10 years of abandonment, grazing had re-started 3–8 years before the study, 12 abandoned pastures which had not been grazed for at least 10 years, and 11 continuously grazed pastures. All restored and most continuously grazed pastures received support under the Finnish agri-environment scheme. All grazing was by cattle. Butterflies and day-flying moths were counted along transects four (1999) or seven (2000) times from May–August. Either searching time (1999) or transect length (2000) were standardized across sites.Study and other actions tested
A replicated, site comparison study in 1999–2000 in southwest Finland (Poyry et al. 2005, same experimental set-up as 2) found that 13 of 32 butterfly and day-flying moth species were less abundant in restored semi-natural grassland than in abandoned (unrestored) grassland. Thirteen out of 32 species of butterfly and day-flying moth were less abundant in restored grassland than in abandoned, unrestored grassland, and a further three species were less abundant in restored grassland than in continuously grazed grassland. Three species were more abundant in restored or abandoned grassland than in continuously grazed grassland. The remaining 13 species had similar abundance in all three grassland types (see paper for data on individual species). Butterflies and day-flying moths were monitored in 1999 or 2000 on 10 restored pastures where, after at least 10 years of abandonment, grazing had re-started 3–8 years before the study, 12 abandoned pastures which had not been grazed for at least 10 years and 11 continuously grazed pastures. All restored and most continuously grazed pastures received support under the Finnish agri-environment scheme. All grazing was by cattle. Butterflies and day-flying moths were counted along transects four (1999) or seven (2000) times from May–August. Either searching time (1999) or transect length (2000) were standardized across sites.Study and other actions tested
A replicated, paired, site comparison study in 2003–2004 in 36 semi-natural grasslands near Lund, Sweden (Öckinger et al. 2006) found that the species richness and abundance of butterflies and burnet moths was similar in recently restored, abandoned and continuously grazed semi-natural grasslands. On restored grassland, the species richness (9 species) and abundance (101 individuals) of butterflies and burnet moths was similar to that on both abandoned (richness: 11 species; abundance: 216 individuals) and continuously grazed grassland (richness: 13 species; abundance: 225 individuals). However, sites currently grazed by sheep (7 species) had a lower species richness of butterflies than sites grazed by horses (13 species) or cattle (12 species), or with no grazing (12 species). From 1999–2003, twelve abandoned, semi-natural grasslands were restored by clearing trees and shrubs, erecting fences, and re-introducing grazing animals. Butterflies and burnet moths were surveyed using transects (150 m/ha) six or seven times in May–August 2003 or June–August 2004 on 12 restored grasslands, 12 abandoned grasslands which had not been managed for 5–15 years, and 12 continuously grazed semi-natural grasslands. Under current management, 12 sites were cattle grazed, six were horse grazed, eight were sheep grazed and 10 had no grazing.Study and other actions tested
A replicated, site comparison study (years not given) in 10 grasslands in England, UK (Woodcock et al. 2012) found that grasslands restored by clearing scrub and restarting management did not develop butterfly communities more similar to existing high-quality grasslands, or increase the number of species present, over time since restoration. The similarity between the butterfly communities on restored and target grasslands did not increase with time since restoration, but was very variable between years (0–73% similarity). The number of butterfly species recorded each year on restored grasslands (~13–14 species/year) remained similar over time. Four species-poor grasslands dominated by competitive plants and scrub were restored by scrub removal. Two of the sites were then managed by low intensity sheep grazing to produce calcareous grassland, while the other two were cut annually with aftermath cattle or sheep grazing to produce lowland hay meadows. Six high-quality grasslands (three calcareous grasslands and three hay meadows) were used for comparison. From April–September each year, butterflies were surveyed weekly on a ~2 km transect at each site for 12–21 years after restoration.Study and other actions tested
A replicated, site comparison study in 2013 on 17 calcareous grasslands in the Diemel Valley, Germany (Helbing et al. 2015) found that grasslands restored by shrub cutting had a higher occupancy and density of blue-spot hairstreak Satyrium spini eggs than unrestored grassland. In restored grasslands, more small buckthorn Rhamnus cathartica bushes had blue-spot hairstreak eggs (20%) than in unrestored (9%) or continuously managed (3%) grasslands. The density and size of egg batches on small bushes were higher in restored grasslands (density: 1.8 batches/plant; size: 2.6 eggs/batch) than in unrestored grasslands (density: 1.0 batches/plant; size: 1.4 eggs/batch). Continuously managed grasslands were intermediate (density: 1.4 batches/plant; size: 2.2 eggs/batch). There were no differences in occupancy, density or size of batches on large buckthorn bushes (see paper for details). Five restored grasslands had been abandoned for >15 years before shrubs were cut back four years before monitoring, and had a high density of small buckthorn (height <130 cm). Five unrestored grasslands had been abandoned for >20 years, and had a dense shrub layer. Seven continuously managed grasslands had been grazed, with irregular mulching, for >20 years, and contained both large (height >130 cm) and small buckthorn. Grasslands were similar in size (ca. 0.9 ha) and separated by >50 m of unsuitable habitat. In March 2013, every buckthorn in each grassland was searched for >10mins to record hairstreak eggs. The number of egg batches/plant, and the number of eggs/batch, were recorded.Study and other actions tested