Cities in the fight against biodiversity loss

Global biodiversity is declining at an alarming rate, with rapid urbanization having largely negative effects on species abundance and diversity. A growing global awareness of the extinction crisis that we face is pushing nations and localities to respond with action. This post will explore whether cities have the potential to positively impact biodiversity and what opportunities there are for local biodiversity action.

Using existing articles in the field of urban ecology, I conducted a literature review to summarize key findings on the topic. In my search, I encountered many articles focused on the negative impacts that urban areas have on wildlife, including pollution, invasive species, and habitat loss. However, the fact that some species have succeeded in adapting to an urban environment suggests that cities do have ecological potential and this potential could be emphasized through intentional design.

So what does this potential look like?

There are a few ways that cities already innately contribute positively to the success of wildlife. Firstly, by providing protection from some of the challenges of the natural landscape. For example, cities can provide alternative or additional food sources when they are scarce in nature, such as winter bird feeders. Additionally,  urban environments typically exclude larger predators, which means less predation of prey species, and less competition for smaller carnivores.

Secondly, cities can increase regional habitat heterogeneity. For example, pollinators may have an easier time in cities whose green spaces offer more habitat heterogeneity than the homogenized agricultural landscape that surrounds the city. There is also the added benefit of lower pesticide exposure.

Thirdly, cities can serve as stop-over sites for migrating species, including many that are endangered. For example, 4 major migratory routes pass over New York City, where city parks reportedly provide stop-over habitat for more than 100 species of migratory song bird.

Last but not least, cities provide ways for citizens to engage in conservation and stewardship. Educational programs, citizen science, and other stewardship opportunities allow the public to participate in conservation issues. A great example is the recovery of the endangered peregrine falcon, whose conservation occurred largely in cities with the help of urban residents. Another example is monarch butterflies, which are disappearing across North America, but are capturing the attention of concerned citizens. Several organizations have encouraged people to plant milkweed, a plant the butterfly’s larval stage depends on, in private gardens. These program have drawn in thousands of eager participants, with over 26, 000 managed monarch gardens registered in 2019.

As you can see, in some ways, cities are already offering habitat and resources to wildlife. So what are a few of the way that cities can maximize this potential and be more biodiversity-friendly?

1. Utilizing urban parks, yards, and gardens

Researchers in the UK have found that these micro-habitats can in many cases support a greater number of plant species than natural habitats in the same region can. This in turn contributes to greater insect diversity. Importantly, the success of these creatures depended on the amount of the yard that contained flowers, as well as whether those flowers were native species. These details are important to keep in mind if we hope to maintain native populations.

In many countries, government groups and NGOs are developing info packets for urban residents that want to take part in this backyard conservation. However, it’s important to note that many participants of these projects are people who already have an interest in conservation. This highlights the need to rope more of the general public into such efforts. Which leads us to…..

2. Public engagement

In addition to developing tools to help wildlife, the key to the success of any urban conservation effort is engaging people whose daily actions impact those species. In other words, we can’t implement conservation strategies in cities without including the people who live in those cities. It’s about more than just education though; recent research shows urban residents who are most engaged in biodiversity issues are those that have had positive experiences in nature.

Urban biodiversity plans have to recognize cities as socio-ecological systems and incorporate the values and attitudes of residents into their strategies. This means understanding the relationship people have to biodiversity in their cities, and promoting positive interactions between the two.

3. Greening and Restoration

The urban matrix already includes small patches of habitat, with public parks, riparian areas, and suburban yards all providing habitat for smaller species. In fact, residential areas can be great birds if mature trees are available, with one study finding that different neighbourhood types in Baltimore each had their own unique composition of bird species. Thus restoring, creating, and expanding these habitat patches maximizes their potential. Some examples of nature-based solutions include:

·      Green roofs

·      Constructed wetlands

·      Restoration of unique native habitat

·      Creation of corridors for connectivity

·      Tree planting

·      Native plant gardens

·      Bioswales

Conserving remaining habitat, restoring lost habitat, and creating new green spaces with location-specific proportions and spatial arrangements of native plants are all ways to foster a more ecologically functional urban landscape.

4. Intentional and explicit strategies

A key aspect of successful urban biodiversity action, identified by several of the authors in my review, is intentional action. For biodiversity solutions to be truly effective, we need coordinated and targeted solutions that explicitly address the problem. In other words, we need to shift away from seeing biodiversity conservation as a positive side-effect of other actions, and toward treating it as a priority in and of itself, by strategically incorporating it into our urban plans and agendas.

For example, implementing biodiversity-sensitive mowing schedules for vegetation, planting ecologically important tree species to create habitat clusters, and providing natural forms of refuge for animals in areas that have become exposed through demolition, are all simple ways to demonstrate consideration for wildlife. 

A systems approach could be effective, particularly if it integrates nature-based solutions into urban infrastructure in the early stages of the design processes, rather than merely tacking them on as an afterthought.  

5. Intentional non-native biodiversity

Lastly, I wanted to include a particularly provocative solution to our biodiversity crisis that I came across . It’s controversial with respect to the effect it could have on native species, but I’ve included it here as some food for thought.

One author argued that any existing biodiversity our cities currently have is accidental. We do not plan what species share our cities with us, rather, we create ecological opportunities through patch habitats and food sources, and species come to take advantage of them. So rather than allowing random non-native species come fill the niche, which is often the case, what if we intentionally chose which ones we introduced into our cities? The author highlights an opportunity to shelter endangered species in cities through this concept, giving the example of the red-crowned amazon, a parrot that’s endangered in its native Mexico, but thriving in urban Los Angeles. He believes intentional non-native biodiversity in cities could be a strategy to save threatened species who could benefit from their unique features. While there is little supporting evidence to suggest this idea would work, it is certainly thought-provoking and begs the question of whether cities hold more biodiversity potential than we’ve traditionally considered.

My review suggests cities have the potential to help in the fight against biodiversity loss if local conservation efforts are thoughtful, explicit, and targeted. Discovering what currently supports biodiversity in cities is critical, as this information can be leveraged to inform conservation strategies going forward. While there are many actions cities can take to restore habitat and foster biodiversity in their jurisdictions, it’s key to engage the public in these efforts, as citizen support will be crucial to their success.    

The ideas presented here have implications for future research and urban planning, and are important given that cities are growing. Local and regional actions have global consequences, and whether cities will have a positive or negative impact on the extinction crisis in the future depends on the implementation of intentional strategic solutions today.

References

• Blaustein, R. (2013). Urban biodiversity gains new converts; Cities around the world are conserving species and restoring habitat. Bioscience, 63(2), 72-77. https://doi-org.ezproxy.royalroads.ca/10.1525/bio.2013.63.2.3

• Kowarik, I., Fischer, L.K., & Kendal, D. (2020). Biodiversity conservation and sustainable urban development. Sustainability, 12(12), 1-8. https://doi.org/10.3390/su12124964

• Nilon, C.H. (2011). Urban biodiversity and the importance of management and conservation. Landscape and Ecological Engineering, 7, 45-52. https://doiorg.ezproxy.royalroads.ca/10.1007/s11355-010-0146-8

• Oke, C., Bekessy, S.A., Frantzeskaki, N., Bush, J., Fitzsimons, J.A., Garrard, G.E., Grenfell, M., Harrison, L., Hartogan, M., Callow, D., Cotter, B., & Gawler, S. (2021). Cities should respond to the biodiversity extinction crisis. Urban Sustainability, 1 (11), 1-4.   https://doi-org.ezproxy.royalroads.ca/10.1038/s42949-020-00010-w

• Panlasigui, S., Spotswood, E., Beller, E., & Grossinger, R. (2021). Biophilia beyond the building: Applying the tools of urban biodiversity planning to create biophilic cities. Sustainability, 13(5), 2450. https://doi.org/10.3390/su13052450

• Shaffer, H.B. (2018). Urban biodiversity arks. Nature Sustainability, 1, 725-727. https://doi-  org.ezproxy.royalroads.ca/10.1038/s41893-018-0193-y

• Spotswood, E.N., Beller, E.E., Grossinger, R., Grenier, J.L., Heller, N.E., & Aronson, M.F.J. (2021). The biological deserts fallacy: Cities in their landscapes contribute more than we think to regional biodiversity. BioScience, 71(2), 148-160. https://doi-org.ezproxy.royalroads.ca/10.1093/biosci/biaa155