The buzz for green cities: urban spaces for people and pollinators

Sustainable Leaders | Global

By Bethan Henderson, Freelance Writer

Published July 11, 2021

The Covid-19 pandemic has shown many city-dwellers tucked away indoors the enormous mental health benefits of spending time in nature. And as urbanisation takes over the world—with 5.2 billion people estimated to live on 1.9 million km2 of urban land by 2030—it is increasingly important to design city spaces to accommodate for the health of their inhabitants, both human and animal.

More specifically, this attention on urban green spaces for the public also creates an opportunity to make cities more suitable for insect pollinators; essential ecosystem players that are being pushed out of rural areas due to harmful agricultural practices.

Brandon Hill park, Bristol, United Kingdom | Martyna Bober / Unsplash

Rates of mood and anxiety disorders are significantly higher in urban areas than in rural areas, as cities generally come with higher crime rates, more pollution, and a lack of connection to nature. Spending time in green spaces generally improves mental health quality, not only by encouraging physical exercise which improves mental stability, but also through psychological restoration.

For example, studies have found a positive correlation between city inhabitants living near streets lined with a high density of trees and reduced antidepressant prescriptions. Even simply viewing greenery from a window and having houseplants has been shown to reduce symptoms of anxiety and depression.

Theories behind this effect include Attention Restoration Theory, which was developed by Rachel and Stephen Kaplan, professors of environmental psychology at the University of Michigan. This theory suggests that nature’s gentle stimuli induce reflection and therefore improve mental wellbeing.

‘Urban green spaces clearly have the potential to improve the mental health of city-dwellers.’

Alternatively, Roger Ulrich’s Stress Recover Theory hypothesizes that humans are hardwired to positively respond to nature because this was an advantageous trait in ancestral populations, helping them seek resource-rich environments. Whatever the mechanism, urban green spaces clearly have the potential to improve the mental health of city-dwellers.

With regard to what kind of greenery humans prefer, people tend to take the greatest pleasure in green spaces with water features, flower plantings, trees, and open lawns—there is a strong positive association between aesthetic preference and mental restoration. Trees, especially, seem to have a disproportionate psychological effect, potentially a result of their providing security and other resources to early humans.

The public also tends to like spaces they think are highly diverse, however there is a large discrepancy between what people think is diverse and what is actually diverse. This is potentially due to poor general knowledge of ecology. Therefore, simply having large patches of greenery benefits humans, with areas of 20% vegetative cover lowering depression and stress by up to 11% and 17%, respectively. Increasing this vegetative cover in green areas to 30% has the potential to reduce anxiety cases by 25%.

Parks should be covered in vegetation, to improve both human mental and pollinator health. | Chuttersnap / Unsplash

City greenspaces offer a home to urban pollinators

There is more uncertainty surrounding the extent to which insect pollinators are actually affected by urbanisation, and there is variation by taxa. Generally, however, there is greater pollinator diversity within cities that have more urban greenery, as the additional vegetation—floral plantings in particular—provides nesting spaces, pollen, and nectar. Insect pollinators gain the most from biodiverse urban green spaces, such as urban grasslands, rather than pedestrianized and heavily maintained areas such as parks.

Biodiverse plantings with herbaceous vegetation, native weed species, and floral species support a variety of pollinator visitors and ensure a well-rounded diet, as flower species differ in protein content and amino acids. Keeping areas unmown is also important, as naturally maintained green spaces have more suitable soil for ground nesting pollinators, allow increased access to flowers, and create space for butterfly and hoverfly larvae to develop.

To compare the two, humans generally benefit more from simple green cover, trees, and aesthetic features, while benefits to insect pollinators depend upon natural maintenance and diverse plantings. Although both parties benefit from different urban greenery in different ways, city spaces can be designed with everyone in mind.

‘Benefits to insect pollinators depend upon natural maintenance and diverse plantings.’

Community gardens are an excellent example of this as they support high abundances of pollinators—significantly higher than other urban landscapes—and those who use them experience lower rates of depression. This solution is less than ideal, however, because land in cities is an expensive commodity and community gardens are often private.

It is more feasible in cities for smaller, unbuildable spaces to be reclaimed by nature and for existing green spaces to be improved. Improving public parks by increasing tree cover, and planting diverse green and floral vegetation would increase pollinator visitation whilst also attracting humans. While it matters less for people, the composition of flora in urban plantings can also be tailored to maximise benefits to pollinators.

Seed mixes should be diverse, including native weed species and perennial species that provide floral resources year after year without needing replanting. Creating more planted meadows would not only support pollinator communities, but would also reduce mowing and other maintenance costs. Some cities in the USA, for example, have implemented greatly successful ‘No Mow May’ schemes, which have demonstrated that unmown urban green spaces have three times the bee richness and five times the bee abundance of mown areas.

Even many small green patches can add up to create a green city! | Chuttersnap / Unsplash

Other cities making progress in this area include Edinburgh, Scotland. One study overlaid data on pollinator hotspots with areas of health deprivation to identify locations where greenery would benefit both parties. The Meadow Bristol project also aims to increase sustainability and beautify the city simultaneously through urban meadows, including wildflower meadows. The wildflower meadows in particular have been designed with conservationists acting as advisors, in order to ensure species diversity.

At a time when everything seems to be a trade-off between human gain and sustainability, projects like these that combine the interests of both people and nature can reframe how we look at conservation. Given the recent rise in awareness of mental health issues, and the ongoing physical health concerns surrounding obesity and heart disease, urban green spaces are a low-cost, preventative solution supporting both aspects of human health.

Unfortunately, the intrinsic value of nature is often not enough of an incentive to invest in conservation, therefore, highlighting these socio-economic benefits to humans can hopefully drive more funding towards public green spaces.

Featured Image: Hector Argüello Canals | Unsplash

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