Gardens reduce seasonal hunger gaps for farmland pollinators

Gardens can benefit pollinators living in surrounding farmland landscapes,
but the reason for their value is not clear. Gardens are no different from
many semi-natural farmland habitats in terms of the quantity of floral
resources (pollen and nectar) they produce, but the timing of their
resource supply is very different, which may explain their value. We show
that gardens provide 15% of overall annual nectar in farmland landscapes
in Southwest UK, but between 50% and 95% during early-spring and
late-summer when farmland supplies are low. Gardens can therefore reduce
seasonal nectar gaps experienced by farmland bumblebees. Consistent with
this pattern, bumblebee activity increased in gardens relative to farmland
during early spring and late summer. An agent-based model reinforces this
point, showing that timing, not quantity, of garden nectar supply enhances
bumblebee colony growth and survival in farmland. We show that over 90% of
farmland in Great Britain is within one kilometre of a garden and
therefore positive actions by gardeners could have widespread spillover
benefits for pollinators across the country. Given the widespread
distribution of gardens around the world, we highlight their important
interplay with surrounding landscapes for pollinator ecology and
conservation.