A team of researchers from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), conducted a study to assess the sustainability of urban beekeeping in Switzerland, through the use of a computational model.
How did researchers assess the threat of beekeeping in Swiss cities?
Beekeeping is currently thriving in Swiss cities. However, the uncontrolled increase in bees and honeybees is creating an escalating pressure for wild pollinators, which is essentially threatening urban biodiversity. This therefore suggests that beekeeping in cities requires better regulation.
Scientists from WSL, Joan Casanelles Abella and Marco Moretti, developed and utilised a computational model that compared the existing amount of hives in fourteen Swiss cities with the available ‘flowering environment’ between the years 2012-2018.
They discovered that the amount of beekeeping sites nearly tripled in that time, from 3,139 to 9,370. The model weighs the honeybees’ demand for green space against their actual availability, and for the majority of the cities studied, the model indicated a negative balance, indicating that there is an inadequate supply of floral resources to satisfy the demands of the honeybees.
“The key message from our results is that urban green spaces can’t keep up with the existing density of hives,” commented Casanelles Abella. The researchers’ findings reinforce a similar trend observed in other European cities such as Paris, Berlin, and London.
In comparison to this, a scientific study from Great Britain revealed that 7.5 beehives per km2 of green space is a suitable limit for a sustainable beehive density. In Switzerland, however, only rural areas comply with this value, whereas in cities the hive distribution is much denser and frequently exceeds the limit. Even when the researchers replicated an expansion in urban green space with a model calculation, there was no considerable development.
“Increasing green spaces by 75% is very unrealistic anyway, but it shows that in truth there are simply not enough resources,” added Abella.
What competition are bees facing regarding pollination?
Bees and honeybees are not the only pollinating insects in cities. “When you overcharge a system beyond its carrying capacity, you automatically exhaust all its resources. In turn, this causes the other organisms that depend on the same resources to suffer,” explained Abella.
This means that the food shortage impacts all insects that feed on the same flowering plants that the honeybees do, including wild bees. Of the approximately 600 wild bee species in Switzerland, roughly 45% are considered endangered. Cities can harbour a surprisingly large diversity of wild bees’ species; a recent WSL study revealed that Zurich harbour approximately 164 different species of bees.
The exact extent of the negative impacts that beekeeping is having on biodiversity is difficult to determine. Urban beekeeping contributes to the already decreasing wild bee diversity, with bees suffering from the combined actions of all ongoing global stressors, including climate change, lack of flower resources, and pests.
“We are in a phase where biodiversity is steadily declining and nature is already facing major challenges,” noted researchers.
How can these negative impacts be managed?
Researchers stress that there is primarily a lack of information and control on the subject. “People often perceive honeybees as wild animals because they live and move freely. In reality, however, they are kept and bred just like other livestock. And as for these, humans must provide an adequate food supply for honeybees,” said Abella.
Traditionally, beekeeping is a form of agriculture, but in cities, the breeding of honeybees has progressively become a recreational activity. The vast majority of people who are keeping honeybees are individuals who want to contribute to a natural environment.
It is relatively easy to get started with recreational beekeeping; the only legal requirement is the registration of the new bee colony— training is merely a recommendation, and there are no regulations regarding where and how far apart the hives should be placed.
”We need to come up with a clever strategy to control the density of beehives, just like you do with other livestock, without negatively affecting people’s good will,” Abella concluded.
Researchers have suggested approaches that could help improve the current negative impacts of beekeeping, such as introducing legally required minimum distances between bee colonies, defining areas in the city of high value for wild bees, as well as better monitoring of the available floral resources. For example, this could be accomplished by using biodiversity maps.
Additionally, the public needs to be better educated about the adverse impacts of beekeeping, so that urban biodiversity is not thrown out of balance. Cities contain important habitats and, if managed sustainably, they could contribute significantly to biodiversity conservation.
