Floral richness and seasonality influences bee and non-bee flower interactions in urban community gardens

Urban Farm DB summary

A study in 30 urban community gardens in Berlin and Munich, Germany, observed 20 focal plant species and 13 common bee and non-bee flower visitor groups, examining how landscape urbanization and the availability of floral and nesting resources within gardens affected the complexity (nestedness, linkage density, connectance) of pollinator interaction networks. Dominant flower visitors changed over the growing season, with non-bee visitors such as ants and flies dominant early in the season and bees becoming important later. Nestedness of the flower visitor network increased with floral richness within gardens, while floral abundance, the impervious surface surrounding gardens, garden size, and nesting resource availability did not strongly influence the networks. The findings indicate that high floral richness in community gardens can ensure the complexity and stability of flower visitor networks, that non-bee visitors play an important role especially in the shoulder seasons, and that urban gardeners play a key role in mediating flower visitor interactions through their gardening practices.