Individual study: Establishment of clover-rich field margins as a forage resource for bumblebees Bombus spp. on Romney Marsh, Kent, England
Gardiner T., Edwards M. & Hill J. (2008) Establishment of clover-rich field margins as a forage resource for bumblebees Bombus spp. on Romney Marsh, Kent, England. Conservation Evidence, 5, 51-57
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Sow uncropped arable field margins with an agricultural nectar and pollen mix
Arable margins sown with legume-grass seed mix had higher species richness of bumblebee forage plants (almost 100% cover of Alsike clover and red clover one year after establishment) over four years, compared to naturally regenerated margins on farmland at Romney Marsh, Kent, England (Gardiner et al. 2008). Bee visits were not reported in this study. Fixed-time transect walks in the clover margins are reported elsewhere (Edwards & Williams 2004) to have demonstrated a 300-fold increase in bumblebee forager numbers in the margins planted with clover, but unfortunately, no control count was carried out for comparison. However, the clover-sown plots were invaded by perennial grasses in the third and fourth years of this study, and flower numbers fell substantially.
Plant nectar flower mixture/wildflower strips
A replicated, controlled study from 2001 to 2004 in the UK (Gardiner et al. 2008) found arable margins sown with a legume-grass seed mix had more bumblebee Bombus spp. forage plant species (almost 100% cover of Alsike clover Trifolium hybridum and red clover T. pretense one year after establishment) over four years, compared to naturally regenerated margins. The cover of Alsike clover declined from a peak of approximately 33% in 2002 to 2.5% in 2004, whilst red clover cover peaked at around 85% in 2003 and declined to 20% in 2004. Clover-sown plots were invaded by perennial grasses including false oat grass Arrhenatherum elatius in the third and fourth years of the study, when clover cover decreased substantially. Bee visits were not reported in this study however the results of fixed-time transect walks in the clover margins are reported in (Edwards & Williams 2004) which found a 300-fold increase in bumblebee forager numbers in the margins planted with clover, however no control count was carried out for comparison. Two 6 m-wide margins were established on one farm, and subdivided into three plots. There were two margin types: naturally regenerated, or sown with a mixture of grasses and leguminous species including two species of clover. Three different management treatments were applied to the subplots in the first year (2001): cut three times with cuttings left, cut three times with cuttings removed, cut six times with cuttings left. From 2002 to 2004, all plots were cut in late summer and the cuttings removed. Forage plants were monitored in 0.25 m2 quadrats every 1 m along a 30 m transect in early August 2001, 2002, 2003 and 2004.
Edwards M. & Williams P. H. (2004) Where have all the bumblebees gone, and could they ever return? British Wildlife, 15, 305-312.