City gardens are becoming increasingly important habitats for bees and other insect pollinators, which face a range of threats in farmland.
Katherine Baldock at the University of Bristol, UK, and her colleagues recorded the number of species of flowering plant and pollinating insect at 360 sites across four British cities — Bristol, Reading, Leeds and Edinburgh. Residential gardens, particularly in wealthy neighbourhoods, had the greatest abundance of flowering plants and harboured up to 50 times more bees than artificial surfaces such as car parks.
Bees also thrive in allotments, but because these community gardens occupy less than 1% of urban space, their positive impact on city pollinators is limited, the team found. Enlarging community gardens and encouraging weeds such as common daisies (Bellis perennis) and dandelions (Taraxacum officinale) to grow in public parks — easily achieved by mowing less often — could make communities of city pollinators more resilient, the authors suggest.