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Providing evidence to improve practice

Action: Introduce agri-environment schemes to benefit wild bees Bee Conservation

Key messages

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Four replicated trials in Europe have shown enhanced diversity and/or abundance of foraging wild bees on land managed under various European agri-environment schemes, relative to conventionally-managed fields or field margins. These schemes were the Swiss Ecological Compensation Areas (one replicated trial), the German organic arable farming option (one replicated trial), the Dutch botanical and meadow bird agreements (one replicated trial, very low numbers of bee species) and the Scottish Rural Stewardship Scheme (one replicated trial, also included nest-searching queen bumblebees).

Four replicated trials in Europe found that the number of bees and/or bee species is not enhanced on land managed under agri-environment schemes, including meadow bird agreements in wet grassland in the Netherlands, measures to protect steppe-living birds and compensation measures around a National Park in Spain, and 6 m wide grass field margin strips in England (one replicated trial for each).

On a wider landscape scale, two replicated trials in the UK have found bumblebee populations were not enhanced on farmland managed under agri-environment schemes. One trial compared the reproductive success of colonies of the buff-tailed bumblebee Bombus terrestris, the other compared queen bumblebee numbers in spring in conventionally managed field margins, on farms with and without agri-environment schemes.

 

Supporting evidence from individual studies

1 

In a replicated trial with 39 pairs of fields, Kleijn et al. (2001) found meadow bird agreements and/or botanical agreements, aimed at conserving wading birds and species-rich vegetation, respectively, in the Netherlands, enhanced the number of bee species relative to conventionally managed control fields. Bee diversity was very low in this study, sampled using 15-minute transect walks (not sweep nets). Three species, honey bee Apis mellifera, common carder bee Bombus pascuorum and buff-tailed bumblebee B. terrestris, accounted for 85% of bees recorded.

2 

Goulson et al. (2002) compared the growth of experimental B. terrestris colonies placed on 10 farms with substantial conservation measures with those placed on 10 conventional arable farms. Conservation measures included conservation headlands, set-aside and minimal use of pesticides. This study found no measurable difference between colonies on the different types of farm. The authors suggest this is because B. terrestris has a foraging range that extends beyond individual farms, which may not be true for other bumblebee species.

3 

Kleijn & Sutherland (2003) reviewed studies of the effectiveness of European agri-environment schemes in published and unpublished literature. Three out of the 62 studies included bees. Two studies (Kleijn et al. 2001, reported above, and Allen et al. 2001) found more bees (more species of bee in the case of Kleijn et al. 2001) on agri-environment fields compared to control fields under certain schemes. The third study (Kleijn et al. 1999) is not reported to have found a difference in bee abundance or species richness between seven agri-environment fields and seven control fields.

4 

A replicated controlled trial of agri-environment schemes on 21 pairs of fields in each of five European countries carried out in 2003 found significantly greater abundance and diversity of wild bees on fields managed under agri-environment schemes than on control fields in Germany and Switzerland, but no significant difference in the Netherlands, England or Spain (Kleijn et al. 2006). The agri-environment management options that benefited bees in this study were organic arable farming in Germany and Ecological Compensation Areas in Switzerland. Those that did not were meadow bird agreements in wet grassland in the Netherlands (bees sampled with sweep nets and transect walks), measures to protect steppe-living birds and compensation measures around Caballeros National Park in Spain, and 6 m wide grass field margin strips in England.

5 

In a replicated controlled trial involving 10 farms in east and central Scotland, Lye et al. (2009) compared numbers of nest-searching and foraging queen bumblebees Bombus spp. on land that had been managed under three different options of the Rural Stewardship Scheme (unsprayed grassy field margins, species-rich grassland and hedgerows) for three years with conventionally managed land of the same type. On farms with the agri-environment scheme, transects under the scheme attracted significantly more nest-searching and foraging queen bumblebees than conventionally managed transects. However, on conventionally managed transects, there was no significant difference between farms with and without agri-environment schemes in numbers of nest-searching queens, and conventionally managed farms had more foraging queens.

This section covers studies or reviews that examine the impacts of a range of agri-environment schemes, with reduced agrochemical use in common. For evidence relating to specific agri-environment prescriptions, see also the following sections from the chapter on Land Use Change Due to Agriculture: Restore species-rich grassland, Increase areas of rough grassland for bumblebee nesting, Provide grass strips at field margins, Manage hedges to benefit bees, Sow uncropped arable field margins with an agricultural nectar and pollen mix, Sow uncropped arable field margins with a native wild flower seed mix, Leave arable field margins uncropped with natural regeneration, Reduce the intensity of farmland meadow management, Reduce grazing intensity on pastures and Leave field margins unsprayed within the crop (conservation headlands). Some of the studies included here are also included under the relevant specific sections.

Additional references

Allen D.S., Gundrey A.L. & Gardner S.M. (2001) Bumblebees. Technical appendix to ecological evaluation of arable stewardship pilot scheme 1998-2000. ADAS, Wolverhampton, UK.

Kleijn D., Boekhoff M., Ottburg F., Gleichman M. & Berendse F. (1999) De effectiviteit van agrarisch natuurbeheer. Landschap, 16, 227-235.

Referenced papers

Please cite as:

Dicks, L.V., Showler, D.A. & Sutherland, W.J. (2010) Bee conservation: evidence for the effects of interventions. Pelagic Publishing, Exeter, UK