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Corvus Blog Post

Are Municipalities Uniquely Equipped to Accommodate Biodiversity?

Updated: Jan 17, 2023

A respected colleague's comment brought me up short, and then made me think about municipalities and biodiversity in 3-D

I remember being at a meeting in Edmonton this one time. The room we were in was delightful because it had massive windows along one wall that looked out from our sixth-floor vantage point over Edmonton’s gorgeous river valley. I had positioned myself intentionally on the side of the table that got the view, with full recognition of the impact this would have on my ability to focus on the meeting.

If you have not seen Edmonton’s river valley, make the time to do so. Because the North Saskatchewan River is so deeply incised as it passes through the city, the banks are large and steep, and lush, even in the middle of the downtown. Last year, a lynx wandered up from the valley onto the legislature grounds, and hung out under a tree for a while (perhaps as a one-creature political wildlife protest). In what might be my proudest moment as an Albertan, a legislature security guard arrived on the scene to stand at a distance and direct people away from the large cat.

Anyway, my focus at the meeting was something like the start of this blog, but it snapped back when a conservation biologist with a doctorate, who was sitting across from me, said, “There is no biodiversity in cities.” I think I might have been brought up short by this statement, even if his silhouette had not been ringed by the thick trees on the far bank of the river.

Now I should note, I have a lot of respect for this person, so even though I disagreed, I couldn’t dismiss the comment. Instead, it made me think, “I wonder what he means by biodiversity?”

The international Local Governments for Sustainability always lists Edmonton as their biodiversity poster child. Organizations, municipalities, and agencies around the world point to initiatives like Edmonton’s green network strategy and its wildlife passage guidelines as stand-out initiatives. So this was a very bold statement.

I think my colleague’s frame of reference was one of wildness, species richness, and historical species complement. These are all perfectly valid lenses through which to view/assess biodiversity. So, I had to ask myself, how was I viewing biodiversity, and why did I think cities are actually capable of more than just biodiversity participant ribbons?

I concluded there were two reasons, one ‘ecological’, and the other - perhaps more important one - is ‘systems’ based. I also concluded that this was not a topic I would bring up at a cocktail party, were I ever to experience such a thing. “So what do you do?” “Well I sit around thinking about things like systems and municipal policy, and then I write about it.” “And people read such things.” “Hmm, not quite sure yet.”

Perhaps you should grab a cocktail before delving further.

Ecological rationale

Biodiversity, as measured by any number of metrics (number of species, availability of habitat, connectivity of systems, etc.) has been taking a beating over the last several decades, and cities (or rather urbanization) appear to have played a big in that. I think it is arguable that taking the same million or so people and spreading them across the landscape in a low-density way, would be worse, but there is no denying that the footprint of any city involves significant habitat loss relative to the same land base pre-city.

What my colleague’s comment made me think about was biodiversity ‘on a spectrum’. Much ecological conservation activity focuses on biodiversity ‘hotspots’, and Key Biodiversity Areas, and high-quality habitats. This is important, without a doubt, but we ignore what another of my colleague calls “the ecological middle class” at our peril. Exercises focused on hot spots, rarity, and exceptionalism will always keep our attention on the top 10%, but a system cannot survive on only 10% (should we educate only the top 10% of students and ignore the rest?). This becomes a race to the bottom, because as ‘biodiversity’ in general shrinks, that top 10% will also decrease rapidly. Our grand goal then becomes “The Top Ten Percent ... of what’s left on any given day.”

The comment also made me think about how “pristine” fits with biodiversity. There is a popular sentiment that high biodiversity correlates with lack of human influence. There is definitely truth to this, as shown by the impact of roads on species survival, the role of ecological reserves as species ‘sources’, and how human food affects the health and safety of wildlife. However, we no longer have systems that are not in some way human affected; air pollution, greenhouse gases, water pollution, and population growth have ensured that. Climate change has made ‘natural range of variation’ a very wobbly foundation for ecological projections and conservation planning. When we think of pristine, we tend to think of how ‘untouched’ the pieces we can observe are, but biodiversity is more realistically dependent on the pristine-ness of ‘systems’. In other words, how well can the ecological system function, regardless of whether we are standing there inside it?

Perhaps one of the hardest concepts to reconcile with a view of pristine nature is the novel or emerging ecosystem. These are ecological systems that were human-created or whose emergence was heavily influenced, but which are now functioning — ecologically — on their own. The oft-cited example is a managed forest that was abandoned a decade ago, and now thrives ecologically subject to its own rhythms (sustaining wildlife, cycling water, cycling oxygen, cycling nutrients, etc.). The great dilemma here is there are no ‘analogs’ for these systems; they are wholly products of the ‘anthropocene.’

Do we want all ecological systems to be these human-nature hybrids? Personally, I don’t think so, but we have to admit they exist, and (more challenging) we have to admit that they contribute to biodiversity, even if we don’t know how, let alone how to measure that.

Cities are rife with these types of ecosystems.


Perhaps what struck me even more strongly in my colleague’s comment was how it reflected on the perception of biodiversity as a collection of ‘pieces’ versus a collection of ‘systems’. The biological pieces in a city are generally fewer than they are in less-urbanized areas, no question: fewer types of large mammals, fewer types of birds, fewer types of vegetation, etc. But are there fewer systems? Are those systems ‘lesser’?

Personally, I believe they are lesser, but I think our usual measuring sticks don’t help us with that assessment. We tend to make that assessment simply by standing back, looking, and assessing whether we can see a human-created thing: if we can, it is lesser; if we can’t it is more biodiverse. In reality, cities imperil biodiversity when wildlife movement is impaired, surfaces are hardened and impermeable to water, trees are all one species, air-borne pollutants overwhelm natural filtration, ‘problem’ wildlife are removed, etc. Most, if not all, of these ‘system impairments’ are very capable of being managed in an urban landscape. To the extent of ‘high biodiversity’? I don’t think so. To the extent of ‘upper middle class biodiversity’? Yes, I think so.

The reason I believe that was a bit of a surprise to me.

Biodiversity is not a single system. Nor is it a set of systems where each occupies its own discrete space. It is a set of intermingled, intermeshed systems, flowing through and between each other; sometimes relatively independent, sometimes highly dependent on each other.

Adequately managing for that in the ‘anthropocene’, in the era of heavily human-affected systems, is a huge challenge. And by ‘managing’ I mean creating the circumstances where each system can function with the minimum amount of impairment. That’s when it struck me that few entities have the same experience and expertise in managing multiple, spatially-extensive systems as do cities and other municipalities.

Cities are not the exclusive domain of one type of system. There are many, many systems, layered on each other on the exact same land base, fully aware of each other, yet able to function fully, and even to intermingle and support each other. The existence of the road system does not preclude a power grid; nor does the sewage system preclude a sidewalk network; nor does the zoning system preclude gas lines. In some places one system will take precedence, and we say you cannot walk on the freeway, or that a power sub-station will allow no roads through it. In various places the systems will come into conflict and we actively manage that. Sometimes we will think in 3-D to do that, and move the power lines above, the water lines below, and pass the roads along the surface. Sometimes we will give precedence to one system for a time-limited period, like when the vehicle transport system must allow the pedestrian transport system to cross the roads at a light.

Managing for biodiversity in an urban system requires us as conservationists to help municipal managers to view biodiversity as another set of systems, a set they may be uniquely qualified to accommodate. These ‘additional’ systems provide significant benefits to citizens, and need to be overlain on the systems already being managed. The overlaying of biodiversity systems requires the exact same management perspective:

  • These systems need to all exist in the same place at the same time;

  • Some elements of these systems will need to be inviolate (like the barb-wire fence around the electrical substation, or a natural area devoted to habitat);

  • Sometimes they will have to be considered in 3-D, seeking places where one system needs to go under another system or over another system (like a power line going over a road, or a wildlife passage culvert going under a road);

  • Sometimes precedence will have to be considered in a temporal way (like when pedestrians get the right of way over cars at an intersection for a time, or when seasonal wildlife movement is prioritized);

  • Sometimes practices will be required because they benefit two systems (like permeable surfaces needed to decrease the strain on storm water infrastructure, and to promote recharge of aquifers)


And then they said the meeting was over, and I realized my colleague across the table from me looked uncomfortable, like someone had been staring at them for a really long time. Or perhaps like someone had been reading waaay too much into something they had just said.


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