Bees in the city
AFor most of the twentieth century, cities were regarded as hostile territory for pollinating insects. Concrete, traffic and pollution seemed to leave little room for the bees, butterflies and hoverflies on which a third of the world’s food crops depend. Recent surveys, however, have challenged that assumption. In several European cities, researchers have recorded more species of wild bee in parks, gardens and railway embankments than in the intensively farmed countryside that surrounds them.
BThe explanation lies partly in what modern agriculture has removed. Vast fields planted with a single crop provide a burst of flowers for a few weeks and then nothing at all, while hedgerows and wildflower meadows have been cleared to make room for machinery. Urban green spaces, by contrast, offer a patchwork of ornamental plants that flower at different times from early spring to late autumn. Pesticide use in private gardens is also generally lower than on commercial farms, although it is by no means absent.
CNot everyone is convinced that cities are a refuge. Some ecologists warn that the enthusiasm for rooftop beehives may be doing more harm than good. Honeybees kept by hobbyists are managed animals, and in high numbers they compete with wild species for the same limited supply of nectar and pollen. A study in one capital found that as the number of registered hives rose sharply over a decade, the availability of flowers per colony fell to a level the authors described as unsustainable.
DThe emerging consensus is that the quality of urban habitats matters more than the number of hives. Planting native flowering species, leaving areas of lawn uncut and providing bare soil for ground-nesting bees are all inexpensive measures. Several city councils have now replaced bedding plants on roundabouts with perennial wildflowers, a change that also reduces maintenance costs.