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Journal of Applied Ecology<br>
Online Early<br>
doi:10.1111/j.1365-2664.2006.01249.x<br>
Volume 0 Issue 0<br>
<br>
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Comparing the efficacy of agri-environment schemes to enhance bumble bee
abundance and diversity on arable field margins<br>
C. CARVELL *, W. R. MEEK *, R. F. PYWELL *, D. GOULSON † and M.
NOWAKOWSKI ‡ <br>
<a name="h1"></a> Summary<br>
<b>1.</b> Declines in abundance and diversity of bumble bees
(<i>Bombus</i> spp.) in Europe have been linked to agricultural
intensification and the resulting loss of suitable foraging and nesting
habitats. Environmental Stewardship (ES) is a new scheme in England
offering the opportunity to restore habitats of value for these important
pollinators to agricultural land. Scientific evaluation of the options
prescribed within the scheme is essential to ensure that their objectives
are met and that the benefits can be realized by the full bumble bee
species assemblage.<br><br>
<b>2.</b> We compared the efficacy of different ES options for field
margins on arable land in enhancing the abundance and diversity of
flowering resources and foraging bumble bees. Our study was conducted
over 3 years using a multisite experiment.<br><br>
<b>3.</b> Overall, uncropped margins sown with mixtures containing nectar
and pollen-producing plants were more effective in providing bumble bee
forage than margins sown with a grass mix, allowed to regenerate
naturally or managed as conservation headlands.<br><br>
<b>4.</b> A mixture of agricultural legumes established quickly and
attracted on average the highest total abundance and diversity of bumble
bees, including the rare long-tongued species <i>Bombus ruderatus</i> and
<i>Bombus muscorum</i>. However, marked differences were observed between
species and sexes in their responses to field margin management over
time.<br><br>
<b>5.</b> A diverse mixture of native wildflowers attracted more of the
shorter-tongued <i>Bombus</i> spp. and provided greater continuity of
forage resources, especially early in the season. Allowing <i>Cirsium</i>
spp. to flower on such margins also increased their attractiveness to
male bumble bees.<br><br>
<b>6.</b> <i>Synthesis and applications</i>. Our results suggest that the
legume-based 'pollen and nectar flower mix', as prescribed under Entry
Level Stewardship in England, can quickly provide a highly attractive
forage resource for bumble bees, but that issues of seasonal flowering
phenology and longevity of the mixture need to be addressed.
Establishment of 'floristically enhanced margins' under Higher Level
Stewardship will be important to provide diverse perennial communities of
forage plants and to support a greater range of <i>Bombus</i> spp. and
other pollinators. The population-level responses of bumble bees to
introduced seed mixtures and other agri-environment options require
further study in order to maximize the benefits of such schemes in
intensively farmed landscapes.<br>
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