Action: Restore species-rich grassland vegetation
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One replicated controlled trial in Scotland showed that species-rich grassland managed under agri-environment schemes attracted more nest-searching queen bumblebees but fewer foraging queens in the spring than unmanaged grassland.
Three small trials, two in the UK and one in Germany, found that restored species-rich grasslands had similar flower-visiting insect communities (dominated by bees and/or flies) to paired ancient species-rich grasslands.
Supporting evidence from individual studies
A study in eastern England of the pollinator community on a species-rich grassland restoration experiment compared to native grassland of the same plant community found a greater diversity of pollinating insects on the restored hay meadow site than on the ancient meadow (Dicks 2002). Six common species of bumblebee were recorded at both sites, and the most abundant insect visitor was a bumblebee on both meadows: white-tailed bumblebees Bombus terrestris/ lucorum at the restored site, red-tailed bumblebees B. lapidarius at the ancient meadow site. Seven and five species of solitary bee were recorded at restored and ancient sites respectively.
A comparison of two restored hay meadows with two ancient hay meadows in the Bristol area, England (Forup & Memmott 2005) found no consistent differences in the abundance or diversity of pollinating insects (dominated by bees and flies) between ancient and restored sites, and considered the pollinator community to be effectively restored.
A replicated, controlled trial of the species-rich grassland management or restoration option under the Rural Stewardship agri-environment scheme in Scotland (Rural Stewardship Scheme, RSS) found that RSS species-rich grassland attracted more nest-searching queen bumblebees Bombus spp. but fewer foraging queens than areas of naturally regenerated, largely unmanaged grasslands (Lye et al. 2009). Five RSS farms were paired with five conventional farms. Across all farms, unmanaged grassland on conventional farms attracted the highest abundance of foraging queen bumblebees (over 4 queens/100 m transect, compared to less than 3 foraging queens/100 m transect on species-rich grassland), also in comparison with hedgerow and field margin transects. Unmanaged grassland transects had more nectar and pollen-providing flowers than species-rich grassland in April and May, when queen bumblebees are on the wing.
A comparison of two restored sandy grassland and riverine sand dune complexes with the target semi-natural grassland communities near the River Hase, Lower Saxony, Germany found no significant difference in the number of bee species between target and restored sites in any study year, two to five years after restoration (Exeler et al. 2009). Bees were more abundant at semi-natural sand dunes than at restored sand dune sites, but this was not true for the semi-natural sandy grassland sites, characterised by maiden pink Dianthus deltoides and thrift Armeria elongata.
- & (2002) The structure and functioning of flower-visiting insect communities on hay meadows. PhD thesis, University of Cambridge. The structure and functioning of flower-visiting insect communities on hay meadows
- Forup M.L. & Memmott J. (2005) The restoration of plant-pollinator interactions in hay meadows. Restoration Ecology, 13, 265-274
- Lye G., Park K., Osborne J., Holland J. & Goulson D. (2009) Assessing the value of Rural Stewardship schemes for providing forage resources and nesting habitat for bumblebee queens (Hymenoptera: Apidae). Biological Conservation, 142, 2023-2032
- Exeler N., Kratochwil A. & Hochkirch A. (2009) Restoration of riverine inland sand dune complexes: implications for the conservation of wild bees. Journal of Applied Ecology, 46, 1097-1105