HMC Bee Lab: Creating Rooftop Space for City-Dwelling Bees

[1] A picture of a bee on a green roof at Ohio State University.

When you think of an urban area, what do you picture? Does your mind tend to visualize a cityscape: grids of concrete pavement, towering buildings of steel and glass, crowds of people? With this in mind, maybe you’ll be surprised to learn that bees often thrive in urban areas - in fact, even more so than in agricultural regions. This came as a pleasant surprise to me when I first learned of it. I am very interested in landscape architecture, or the design and considerations that go into the landscaping of places such as college campuses or wildlife reserves, and I have been wanting to marry that with my work with bees in the HMC Bee Lab. The best way I can do that is to understand how the field of landscape architecture can be a tool to help bees, which is what makes the urban versus agricultural backdrop so compelling to me.

One study found evidence supporting the claim that agriculture is not able to sustain bees’ foraging needs. This can often be due to the practice of monoculture (planting only one type of crop in a specific field), leading to a lack of variety of food resources, or different types of flowers that bloom in different parts of the year. This is where urban areas offer an advantage for bees, having diverse landscapes in the form of parks, gardens, and so on.

[2] Landscaped gardens at the Schindler House (left) and one of Neutra’s houses (right) in California.

Bee conservation should be a top priority of ours because they provide pollination services to our crops and without them, we would have a much more limited variety of food. There are more types of bees than you might guess, with almost 20,000 different species known. However, as the world becomes increasingly more urbanized, more of their natural habitat is destroyed. While urban areas can provide a diversity of resources to sustain bees with, more can be done to help mitigate the loss of their populations. An ideal future would ensure the ability of both humans and bees to flourish in the same place. We can accomplish this in part by incorporating more greenery in cityscapes, especially in unconventional areas outside of designated greenspaces. One example is through the creation of green roofs.

Bees and Green Roofs

Green roofs are defined as “‘contained’ green space on top of a human-made structure”. In addition to providing benefits such as stormwater management and ventilation, they can function as more green space to support bees with through being extra food sources and nesting sites for different kinds of bees. The more connected such “habitat patches” are, the easier it is for bees to navigate and thrive in an urban area. Unlike public parks and gardens, green roofs help to create this system without fully designating the land space for that purpose, allowing urbanization and bee populations to coexist.

You may be wondering: how can green roofs actually help bees? The tops of buildings are high off the ground, and roofs can be brutal spaces for plants. A study performed by the University of Wädenswil found that there was almost no difference in potential as a resource for bees between a greenspace on a roof and one on the ground. In fact, there are benefits to the elevated green space in having less competition, as well as providing a space that is relatively more natural and less often disturbed than the grounded counterparts. Parks and other public spaces are very frequently maintained (through mowing lawn and cleaning up leaf debris), which can hinder natural growth and plant matter build up that tend to be beneficial for the bees. The study also demonstrated that roofs with plant diversity (as opposed to just sedum, a common choice for green roofs because of its hardiness) attracted twice as many bees and five times as many visits to blooms.

[3] A picture of the roof on the Whole Earth Building in Claremont, California.

The green roof is not a wholly new concept. Many places have begun to incorporate them in different ways. The Studio Gang headquarters in Chicago, Illinois established a rooftop prairie ecosystem, complete with 3 colonies of honeybees. COOKFOX, a company located in New York City, planted a mixture of sedum and other pollinator-friendly plants on 3 terraces of their office, as well as keeping 2 bee colonies. The city of Utrecht in the Netherlands planted sedum green roofs on 316 bus stops, along with other ecofriendly implementations such as LED lighting and solar panels.

Seeing such successful implementations in a number of different cities is a great step towards the future of incorporating green roofs and other unconventional green spaces in urban areas. In this way, we can work towards a future in which humans and bees not only exist together, but thrive because of one another.

[4] A picture of the Bunker Hill Steps and surrounding landscape in Los Angeles, California.

HMC Bee Lab

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Tuesday, May 10, 2022

Creating Rooftop Space for City-Dwelling Bees

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