Bees’ livelihood depends completely on flowers. The pollen flowers produce is bees’ main and only food source. In turn, bees’ presence is crucial to plants’ reproduction. Without pollinators, most plants would go extinct. That’s why it is in our best interest to keep them both in good health.
We are accustomed to the idea of bees living in movable hives to the sides of cultivated crops. There is indeed a growing interest towards the quality of such crops so to provide good quality pollen for bees. A much less explored environment for this kind of activity is the city. Many urban areas are now starting to accommodate a variety of pollinators. As crops get more and more homogeneous, with one or two plant species dominating miles and miles of land, urban areas present a level of heterogeneity that is ideal for many different kinds of pollinators. So it is worth exploring possibilities and enhancing these features with better urban green space planning.
‘Features of urban green space favourable for large and diverse bee populations’ is a study published in 2016 on journal Urban Forestry & Urban Greening that examined a number of green areas in the city of Poznan, Poland. Specifically, it sampled eight green spaces located from 250 to 4,900 metres from the city centre. Some of them were located in areas where buildings were really close to each other, others in areas where buildings were more distanced.
Researchers analysed the variety of bee species and plants found in these sites. They registered about 100 species of pollinators. Bee density in the areas analysed ranged from 247 to 614 bees per hectare. Researchers also drew some evidence-based conclusions on best practices regarding urban green space planning.
For bees it is easier to get around the city when they can find larger green spaces in the vicinity of suburban areas. If parks and gardens are too far away from each other, bees will avoid moving between areas. Some species of bees do not fly long distances in the first place. The reason for this is linked to body size. The smaller the bee, the shorter the trips she will take in order to find food. Urban areas not featuring enough green spaces lose on the possibility to increase their biodiversity.
Let’s now talk about plants. Host plant cover is key for fostering high bee density in urban areas, as it provides a stable food source for bees. Host plants aside, bees are not choosy with the plants they get pollen from to the point they will not eat anymore without it. Some plants just cannot be a food source for bees, but aside from that, most bee species observed in the study do not require a specific plant for their survival as they can get their pollen just as well from a wide range of different plants.
Another thing bees need is space for their nest. Shrubs and undergrowth make it difficult for ground-nesting species – which constituted 60% of the species in the city recorded by researchers – to find space for their nests.
In the end, making space for more parks and gardens, giving a good coverage of host plants and providing nesting locations suited for the species in the area is what will help bees thrive in the city.