Thinking about cities: Were ancient cities greener than modern ones?

  

*This is part of a series called ‘Thinking About Cities’ which are parts of a book I am working on about urban green space that I’ve decided to cut out of the book manuscript.

 

Picture a large modern city. Undoubtedly, your mental image includes a lot of grey. Grey buildings. Grey roads. Maybe grey skies saturated with ozone and particulate matter. Yet we don’t see green as a dominant feature of a city despite the undeniable importance of vegetation and green space to the well-being of a city. 

 

Now picture an ancient city. This image probably has a lot less grey and more browns and greens. We likely see dirt (unpaved) roads, wooden structures, trees here and there, a river with a natural bank, and chickens and other livestock intermingled with human activity. 

 

Were ancient cities inherently greener than modern cities? If so, was this done by design, or by accident, or because humans lacked the technology to completely transform the landscape? Before we delve into this question, we need to think about what a city is and where it comes from.

 

History of the city

Cities have evolved from small permanent settlements to massive human-created landscapes that house large and densely packed populations. As Gordon Childe argued (Childe 1950), the city is a revolution. They represent revolutions of technology, governance, economics, and our relationship with nature and place. Nothing like cities existed in all of human history until about 9-10 thousand years ago when the first known large settlements appeared near the shores of the Mediterranean Sea ( These were Jericho in what is today the West Bank and Catal Huyuk in Turkey. These cities housed somewhere between 2 and 6 thousand people).  To understand the origins of the city, we need to look to the birth of the major civilizations, and to find these, we need to go to the banks of the major rivers of the Middle East and Asia. The Nile, Ganges, Tigris, Euphrates, Indus, Yangtze, and Yellow rivers were the cradles fostering the birth of cities. Just like a germinating seed, cities required water to grow. The rivers were the lifeblood of these new forms of civilization and was essential for the irrigated agriculture that fed populations, a supply of drinking water and for construction, a means for moving waste away from human populations, and were the express highways of the day –moving people and goods.

 

These first major cities were home to several thousand people (certainly less than ten thousand) living in loosely organized communal areas, and though these do not seem like cities by today’s criteria, they were massive by the standards of the day. Pre-agrarian societies supported population densities of about 0.04 people per square kilometre and early agrarian societies, which gave rise to the first permanent settlements, had between 1 and 5 people per square kilometre. Cities today have densities of hundreds or thousands of people per square kilometre.

 

The shift from nomadic cultures to agricultural ones was the necessary development for cities to emerge. Having a permanent source of food drastically changed how people spend their time and allowed them to produce more food than they could personally eat. Sounds trivial, but this new reality allowed for specialized occupations that were not focused on finding and gathering food. The farmer produces the food, while others pursue their own vocational callings like carpenter, artisan, priest, and so on. With new occupations involving training and expertise, innovation and technological development ensued. Metal workers tested new methods and alloys, farmers found ways to increase yield, and the priests and elites organized people and resources.

 

By this point, cities were all but inevitable. As different cultures shared information and technology, small cities began to emerge along the great rivers of the world. These rivers all supported the eventual growth of large cities of ten thousand or more people by about 5 thousand years ago. But the rivers also needed to be controlled. While they were an invaluable resource, they could also be unpredictable and devastating. The ancient city of Petra in modern Jordan, was a thriving capital city between 300 BC and 300 AD, but it was subject to floods after heavy storms and the Petroneans built damns and culverts to reduce flooding. This was not unique to Petra. Many ancient city archaeological sites include evidence of engineered structures designed to control flooding.

 

Cities also required governance. Ten thousand people living together would be chaotic if there wasn’t some sort of government in place to create and enforce rules. For these early cities, this governance was intertwined with religion. Temples were the centre of these early cities and provided guidance, worship, laws, education and were the focal points for political power. People no longer relied solely on family or clan allegiance but were increasingly tied to loyalties to king, high priest, and nation-state. These power structures were important for organizing people and pooling efforts and creativity into larger and larger projects, while promising protection from other nation-states, which were also increasing in power.

 

The emergence of cities was a slow evolution from small permanent settlements to large centrally governed and densely populated ones. It is hard for scholars to say with certainty when the first city appeared because both the evidence has been washed away by time and it is not entirely clear what a city is.

 

For ancient settlements, we can say that the designation as a ‘city’ corresponds to certain features that are necessary to successfully house thousands of people in a small area. These would include: sturdy streets capable of sustaining constant use, dense and organized housing, central governance and control of law enforcement, taxation to pay for services and common good building projects (e.g., aqueducts, city walls, etc.), specialized occupations and trades that provide expertise in various elements of culture, governance and construction of cities (e.g., engineers, teachers, etc.), markets allowing specialized occupations to trade goods and services, because blacksmiths do not grow much food and farmers make few metal objects, and finally cities have large and permanent impacts on local environments.

 

Let us paint a picture of an early city by looking at the largest city in the world during the 11^th century –Kaifeng, China (historically called Daliang or Bianjing). Kaifeng was the capital of the Song dynasty (960 - 1279) and at the height of its glory, it was home to somewhere between six hundred thousand and one million people. We actually know a lot about Kaifeng. China is the oldest continuous civilization on Earth and has tremendous collections of historical documents. Further, Kaifeng is still a major city today with a population of about five million people –a medium-sized city by Chinese standards, but a very large one by standards elsewhere. Most importantly, one of China’s most cherished historical artifacts is a giant scroll measuring 5.25 meters (or over 17 feet) long called “Alongthe River During the Qingming Festival”, and it beautifully depicts Kaifeng life during a national holiday. 

 

A small segment of the painting “Along the River During the Qingming Festival”, painted by Zhang Zeduan (1085-1145). It depicts city life in Kaifeng, China at the height of its prestige when it was the capital city and the largest city in the world.

From this beautiful illustration, you can see the elements of what it means to be a city. First, there are lots of people milling around and participating in different activities. There is trade, we see people moving goods in carts and on camels. There are specialized occupations, notice the tea houses and restaurants. There is organised building construction lining a major road. We see the overwhelming evidence of codified economics as people are buying goods and exchanging money (and gambling!). And with economics we see class inequalities as the lady pulls aside the silk curtains and looks out of the litter, or shoulder carriage, being carried by porters. There is a city gate protecting the population and regulating and taxing the flow of goods. If we move along the scroll, we would see the Yellow River and the docks and ships necessary to move people and goods over great distances. Looking at the amazingly detailed depictions in the scroll, we can almost smell the odours and aromas and hear the sounds that permeate through a dense city. Horses neighing, dogs barking, people shouting, and dishes clanging. This was a city by any definition.

 

So was Kaifeng greener than modern Beijing?

Obviously, Kaifeng, if it existed today, would be a greener city than Beijing. Modern Beijing, or any other megalopolis, is defined by a massive concentration of material and energy that results in a concrete landscape capable of housing millions of people. Keifeng simply had less impervious surface and more space for nature. So, the short answer is yes, ancient cities were physically greener.

 

But if we think of ‘green’ as being a philosophy or approach that directs how we interact with nature, then I don’t think we can say that ancient cities were greener. Humans have created cities precisely to alter local environments to better suit our needs. A city is the embodiment of our innate desire to increase our own fitness by removing threats (from predators and other people), creating security through strength in numbers, and reducing environment unpredictability. We might want to romanticize early human relationships with nature, but the reality is that once technologies were created that advance urbanization, they were implemented and spread rapidly. Being susceptible to flooding, early cities channelized rivers once they were able to. In response to threats from other groups of people, cities around the world accepted being encased in walls as the technologies emerged.

 

The history of cities can be seen as a continuum from small and low-impact settlements to large, urbanized landscapes like Tokyo. What drives a smaller and greener city towards being a megalopolis? So long as the population demand is there and the technologies to build a city exist, the megalopolis is all but inevitable.

 

Unlike previous generations, we are in a unique position to ask the question, what do we want a city to look like? Most of the technological hurdles that would limit urbanization have been overcome. We now have the conceivable ability to create a completely urbanized planet, like Coruscant from Star Wars. But most people would think that this is a bad idea. But is barely constrained sprawl around urban centres like Los Angeles, Mexico City, Delhi, and Toronto not a microcosm for these urbanizing forces that we think are ultimately undesirable?

 

The point is that neither in ancient times nor now do people have an agreed upon vision of urbanization’s endpoint. Urbanization has been and is driven by the mix of demand and technology, but we now need, more than ever, an agreed upon vision and set of principles directing urbanization. We need cities that minimize environmental impact, reduce the effects of inequality, and ensure people realize the potential benefits of green space.

 

So, were ancient cities greener than cites today. Yes and no. While they had less impact on their local environments, the megalopolises of today were written into their DNA. The devaluation of nature has always been a defining feature of cities. Now, more than ever, we need to rethink the relationship between the city and nature, and rewrite what is coded in a city’s DNA.

 

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Childe,V. G. (1950). The urban revolution. Town Planning Review, vol. 21, pg. 3-17.

Do the economics and logistics of field ecology bias our understanding of environmental problems?

Location of Antarctic field stations. Image from Wikipedia.

Field ecology is difficult, time-consuming and expensive. Ecologists need to make decisions about where to do research, and if research questions focus on remote locations, there are likely a lot of constraints limiting options. For example, if research requires work in the Antarctic, odds are you'll be working at one of a few locations on the coast which, depending on the nature of the research, could bias our understanding of ecological or geological processes operating there.

The research needed for some questions can literally occur almost anywhere without much worry about how local context biases findings. That's not to say that local context will not play a role in ecological dynamics, and we should always be mindful of how local conditions influence the processes we are interested in. However, some questions are sufficiently general that we could envisage running an experiment in our backyard. However, there are research questions that necessitate careful consideration of the geographical location of research.

This is especially true for questions that pertain to the consequences of environmental change on ecological systems. The drivers of environmental change, whether it be pollution, nutrient deposition, changing temperature, extreme weather events or changes in precipitation patterns, all vary across the Earth and their impacts are similarly unequal. We shouldn't expect that a 2 degree C increase in average temperature to have the same effect in the tropics as, say, the arctic.

Location of Nutrient Network sites used in Borer et al. 2014

For some research endeavors, the solution to ensuring geographical coverage has been to replicate studies around the world. Take for example studying the effects of nutrient deposition in grasslands. There is a long history of ecologists adding nitrogen, phosphorus, and other nutrients to grasslands at specific locations in short duration experiments. These studies can tell us about how plant dominance might change, but it is difficult to extend this research to other locations facing different nutrient change patterns or that are inherently structured differently. The solution to this shortcoming is best represented by the globally distributed Nutrient Network experiment. The global experiment includes dozens of sites around the world that all replicate a basic set of experimental applications of plant nutrients, which has resulted in some very influential papers about global change effects on grasslands (e.g., Adler et al. 2011, Borer et al. 2014, Seabbloom et al. 2015).

This issue of the geography of research biasing our understanding of the impacts of global change is especially true for understanding the consequences of climate change in the Arctic. This was highlighted superbly by Metcalfe and colleagues recently (Metcalfe et al. 2018). They showed that most of the terrestrial ecology research in the Arctic has occurred in just a few places. And while this work has been extremely impactful and important for understanding the ecology of Arctic systems, they are not located in places undergoing the most drastic changes in climate. Therefore, because of the geographical location of research, we might not have a very good understanding of the impacts of climate change on Arctic ecosystems.

Where research is being done in the Arctic. Panel 'a' shows where publications are coming from and 'b' shows the impact in terms of number of citations (from Metcalfe et al. 2018).

This shows where photosynthesis has changed the most, which does not correspond well to where the research has been done (from Metcalfe et al. 2018).

This type of mismatch in climate change and research requires that ecologists purposefully establish research sites in areas that are rapidly changing. Metcalfe and colleagues suggest that the governments of Arctic nations establish focused research funding to support and promote research in these regions. This of course requires government dedication. The reality is it is cheaper and more efficient to do more research in existing, well supplied, field stations. Arctic scientists and professional organizations need to lobby environment or research government departments, and this research gap is an opportunity for Arctic governments to cooperate and share research costs.

References
Adler, P. B., E. W. Seabloom, E. T. Borer, H. Hillebrand, Y. Hautier, A. Hector, W. S. Harpole, L. R. O’Halloran, J. B. Grace, T. M. Anderson, J. D. Bakker, L. A. Biederman, C. S. Brown, Y. M. Buckley, L. B. Calabrese, C.-J. Chu, E. E. Cleland, S. L. Collins, K. L. Cottingham, M. J. Crawley, E. I. Damschen, K. F. Davies, N. M. DeCrappeo, P. A. Fay, J. Firn, P. Frater, E. I. Gasarch, D. S. Gruner, N. Hagenah, J. Hille Ris Lambers, H. Humphries, V. L. Jin, A. D. Kay, K. P. Kirkman, J. A. Klein, J. M. H. Knops, K. J. La Pierre, J. G. Lambrinos, W. Li, A. S. MacDougall, R. L. McCulley, B. A. Melbourne, C. E. Mitchell, J. L. Moore, J. W. Morgan, B. Mortensen, J. L. Orrock, S. M. Prober, D. A. Pyke, A. C. Risch, M. Schuetz, M. D. Smith, C. J. Stevens, L. L. Sullivan, G. Wang, P. D. Wragg, J. P. Wright, and L. H. Yang. 2011. Productivity Is a Poor Predictor of Plant Species Richness. Science 333:1750-1753.

Borer, E. T., E. W. Seabloom, D. S. Gruner, W. S. Harpole, H. Hillebrand, E. M. Lind, P. B. Adler, J. Alberti, T. M. Anderson, J. D. Bakker, L. Biederman, D. Blumenthal, C. S. Brown, L. A. Brudvig, Y. M. Buckley, M. Cadotte, C. Chu, E. E. Cleland, M. J. Crawley, P. Daleo, E. I. Damschen, K. F. Davies, N. M. DeCrappeo, G. Du, J. Firn, Y. Hautier, R. W. Heckman, A. Hector, J. HilleRisLambers, O. Iribarne, J. A. Klein, J. M. H. Knops, K. J. La Pierre, A. D. B. Leakey, W. Li, A. S. MacDougall, R. L. McCulley, B. A. Melbourne, C. E. Mitchell, J. L. Moore, B. Mortensen, L. R. O'Halloran, J. L. Orrock, J. Pascual, S. M. Prober, D. A. Pyke, A. C. Risch, M. Schuetz, M. D. Smith, C. J. Stevens, L. L. Sullivan, R. J. Williams, P. D. Wragg, J. P. Wright, and L. H. Yang. 2014. Herbivores and nutrients control grassland plant diversity via light limitation. Nature 508:517-520.

Metcalfe, D. B., T. D. Hermans, J. Ahlstrand, M. Becker, M. Berggren, R. G. Björk, M. P. Björkman, D. Blok, N. Chaudhary, C. J. N. e. Chisholm, and evolution. 2018. Patchy field sampling biases understanding of climate change impacts across the Arctic. Nature Ecology & Evolution 2:1443.




Seabloom, E. W., E. T. Borer, Y. M. Buckley, E. E. Cleland, K. F. Davies, J. Firn, W. S. Harpole, Y. Hautier, E. M. Lind, A. S. MacDougall, J. L. Orrock, S. M. Prober, P. B. Adler, T. M. Anderson, J. D. Bakker, L. A. Biederman, D. M. Blumenthal, C. S. Brown, L. A. Brudvig, M. Cadotte, C. Chu, K. L. Cottingham, M. J. Crawley, E. I. Damschen, C. M. Dantonio, N. M. DeCrappeo, G. Du, P. A. Fay, P. Frater, D. S. Gruner, N. Hagenah, A. Hector, H. Hillebrand, K. S. Hofmockel, H. C. Humphries, V. L. Jin, A. Kay, K. P. Kirkman, J. A. Klein, J. M. H. Knops, K. J. La Pierre, L. Ladwig, J. G. Lambrinos, Q. Li, W. Li, R. Marushia, R. L. McCulley, B. A. Melbourne, C. E. Mitchell, J. L. Moore, J. Morgan, B. Mortensen, L. R. O'Halloran, D. A. Pyke, A. C. Risch, M. Sankaran, M. Schuetz, A. Simonsen, M. D. Smith, C. J. Stevens, L. Sullivan, E. Wolkovich, P. D. Wragg, J. Wright, and L. Yang. 2015. Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands. Nat Commun 6.

INTECOL 2017: Building the eco-civilisation

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The International Association for Ecology holds their global INTECOL conference every 4 years, and it was recently held in Beijing, China. Given the location of this meeting, the theme was exceptionally appropriate: Ecology and Civilisation in a Changing World. I say that it was appropriate because no place embodies change more than China’s recent history, and I would argue that China is a prime candidate to benefit from ecological science.

One thing that was clear from the outset of the meeting was that China (both the scientists attending the meeting and the policy apparatus writ large) was serious about the notion of producing an ecological civilisation, or eco-civilisation. In 2007, the Communist Party of China adopted the idea of turning China into an eco-civilisation by incorporating ecological well-being into its constitution. In 2013, the Chinese government started implementing reforms that politically prioritised ecology and the environment. Most prominent of these was that local government officials and administrators were directed to no longer ignore the environmental consequences of development.

China is globally unique in its ability to institute change, literally with the stroke of a pen. Well documented is the ability for the major cities in China to implement drastic change in transportation policy by restricting who can drive when, and building public transit infrastructure at a torrid pace (see a commentary about this). The latest examples of cities’ power over transportation include the fact that electric cars are eligible to receive license plates immediate, while owners of conventional cars are required to wait years or spend tens of thousands of dollars to get their plates. The other example is the flooding of the market with public bicycles that can be parked anywhere and that require a phone app to unlock, and they literally cost cents to use.

A market flooded with a public bike-sharing program in China. These are all shared bikes, available everywhere, and they tend to congregate around bus stops (Photo by M. Cadotte).

I found it to be an interesting juxtaposition to see the multitude of bikes everywhere with the polluted sky that was apparent for the first two days of the conference. This was the very appropriate context for our conference. From the get go the theme of using the science of ecology to improve environmental management and policy seemed to underlie most of the talks and organised sessions. For most Chinese scientists, this is the context in which they work. To them, there is no real separation between human activities and nature, and the two have been intimately linked for millennia. The opening address was by HRH Charles Prince of Wales. Prince Charles eloquently commented on the importance of ecology in the coming decades, as humanity is testing the ecological bounds of the planet, and he encouraged attendees to use their research to affect change.

HRH Charles, Prince of Wales giving the opening address (Photo by M. Cadotte).

Representing the hosting organisation, Shirong Liu outlined all the important ecological advances in Chinese ecology, especially the development of extensive ecological experiments and research networks examining issues like climate change and nutrient deposition. Echoing Prince Charles’ call, Prof. Liu commented on the importance of ecology for Chinese policy, and the many recent policy changes in China, including the establishment of national parks, habitat restoration, climate change mitigation, and the greening of cities.

Given that most of China has been modified by humans, Gretchen Daily’s keynote address seemed incredibly poignant, even though the focus was on Costa Rica. She said that we’ve pretty much protected all the places that are likely to be protected as big parks, and that adding more is increasingly infeasible (China is an outlier). Instead, we should be looking to country sides and other human-dominated landscapes as the places to implement ecological principles to better manage these systems to benefit biodiversity and ecosystem functioning. These systems are where our science needs to pay off.

Evidence of ecosystem services in the Beijing Botanical Garden (Photo by M. Cadotte).

The talks throughout the conference echoed the themes of an ecology on and for human systems. I saw numerous talks from Chinese authors on understanding and managing human impacts, in systems from grasslands to lakes to cities. I participated in a panel discussion on how ecology could be used to create an eco-civilisation, and it was clear that there was a lot of optimism that the next decades will see a renaissance of ecology in policy, I was probably the least optimistic. I am doubtful that, having seen the United States pull out of the Paris Climate Change agreement, the political will can always be relied upon and creating an eco-civilisation depends on China’s ability to increase the standard of living without taxing ecological capacity more than it has. That said, there is currently a global leadership vacuum on the environment, created by political instability in Europe and the United States, and this is the time for China to be an environmental leader. 

Regardless, I saw inspiring talks on restoring ecosystems severely modified by human activity and invasive species, from speakers like William Bond, Carla D’Antonio, and Tom Dudley. I also ran an organised session on the importance of biodiversity in human dominated landscapes which covered topics from habitat fragmentation, to the ecology of cities, to the value of sacred groves in India for biodiversity.

After listening to talks at INTECOL 2017, one cannot help but feel that this is ecology’s time. We are entering an ecological era, and if ever there was a time to use our science to affect change, it is now.

What do we mean when we talk about the niche?

The niche concept is a good example of an idea in ecology that is continually changing. It is probably the most important idea in ecology that no one has yet nailed down. As most histories of the niche mention, the niche has developed from its first mention by Grinnell (in 1917) to Hutchinson’s multi-dimensional niche space, to mechanistic descriptions of resource usage and R*s (from MacArthur’s warblers to Tilman’s algae). Its most recent incarnation can be found in what has been called modern coexistence theory, as first proposed by Peter Chesson in his seminal 2000 paper.

Chesson’s mathematical framework has come to dominate a lot of discussion amongst community ecologists, with good reason. It provides a clear way to understand stable coexistence amongst local populations in terms of their ability to recover from low densities, and further by noting that those low density growth rates are the outcome of two types of processes: those driven by fitness differences and those driven by stabilizing effects that reduce interspecific competition relative to intraspecific competition. Many of the different specific mechanisms of coexistence can be classified in terms of this framework of equalizing and stabilizing effects. “Niche” differences between species in this framework can be defined as those differences that increase negative intraspecific density dependence compared to interspecific effects. If, as a simplistic example, two plant species have different rooting depths and so access different depths of the water table, then this increases competition for water between similar root-depth conspecifics relative to interspecific competition. Thus, this is a niche difference. Extensions on modern niche theory have offered insights into everything from invasion success, restoration, and eco-phylogenetic analyses.

But it seems as though the rise of 'modern coexistence theory' is changing the language that ecologists use to discuss the niche concept. When Thomas Kuhn talks about paradigm shifts, he notes that it is not only theory that changes but also the worldview organized around a given idea. At least amongst community ecologists, it seems as though this had focused the discussion of the niche to an increasingly local scale, particularly in terms of stabilizing and equalizing terms measured as fixed quantities made under homogenous, local conditions. A recognition of the role of spatial and temporal conditions in altering these variables seems less common, compared to the direction of earlier, Hutchinsonian-type discussions of the niche.

Note that this was not Chesson's original definition, since he is explicit that: “The theoretical literature supports the concept that stable coexistence necessarily requires important ecological differences between species that we may think of as distinguishing their niches and that often involve tradeoffs, as discussed above. For the purpose of this review, niche space is conceived as having four axes: resources, predators (and other natural enemies), time, and space.”

On a recent manuscript, an editor commented that the term 'niche processes' shouldn't be used to refer to environmental filtering since (paraphrased) “when ecologists refer to niche processes, they are usually thinking of processes that constrain species’ abundances locally, confer an advantage on rare species...” But is it fair to say that this is the only thing we mean (or should mean) when we discuss niches? I’ve had discussions with other people who’ve had this kind of response – e.g., reviewers asking for simulations to be reframed from niches defined in terms of environmental tolerances to things that fit more clearly into equalizing and stabilizing terms. That is a good description of a stabilizing process, which is termed a 'niche difference' in the modern coexistence literature. But there is still a lot of grey space we have yet to address in terms of how to integrate (e.g.) the effects of the environment (including over larger scales) into local 'niche processes' or stabilizing effects. It's a subtle argument - that we can use the framework established by Chesson, but we should try to do so without dismissing too-quickly the concepts that don't fit easily within it. In addition, elsewhere the niche is still conceptualized in varying ways from comparative evolutionary biologists who talk about niche conservatism and mean the maintenance of ancestral trait values or environmental tolerances; to functional ecologists who may refer to multidimensional differences in trait space; to species distribution modellers who thinks of large-scale environmental correlates or physiological determinants of species’ distributions. 

The niche is probably the most fundamental, yet vaguely–defined and poorly understood idea in ecology. So, formalizing the definition and constraining it is a necessary idea. And modern coexistence theory has provided great deal of insight into local coexistence and thus has allowed for a better understanding of the niche concept. But there is also a need to be careful in how quickly and how much we restrict our discussion of the niche. It's possible to gain both the strengths of modern coexistence theory as well as appreciate its current limitations. Modern coexistence theory isn’t yet complete or sufficient. It’s currently easier to estimate stabilizing and equalizing terms from experimental data in which conditions are controlled and homogenous, and this can inadvertently focus future research and discussion on those types of conditions. Models which consider larger scale processes and the impacts of changing abiotic conditions through space in time exist, but across different literatures, and these need continued synthesis. There is still a need to understand how to most realistically incorporating and understand the complex interactions between multiple species (e.g. Levine et al. 2017). The application of modern coexistence theory to observational data in particular is still limited, and such data is essential when species are slow lived or experimentally unwieldy. Further, when quantities of interest (particularly traits or phylogenetic differences) contribute to both equalizing and stabilizing effects, its still not clear how to partition their contributions meaningfully.

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The value of ecology through metaphor

The romanticized view of an untouched, pristine ecosystem is unrealistic; we now live in a world where every major ecosystem has been impacted by human activities. From pollution and deforestation, to the introduction of non-native species, our activity has influenced natural systems around the globe. At the same time, ecologists have largely focused on ‘intact’ or ‘natural’ systems in order to uncover the fundamental operations of nature. Ecological theory abounds with explanations for ecological patterns and processes. However, given that the world is increasingly human dominated and urbanized, we need a better understanding of how biodiversity and ecosystem function can be sustained in the presence of human domination. If our ecological theories provide powerful insights into ecological systems, then human dominated landscapes are where they are desperately needed to solve problems.

From the Spectator

This demand to solve problems is not unique to ecology, other scientific disciplines measure their value in terms of direct contributions to human well-being. The most obvious is human biology. Human biology has transitioned from gross morphology, to physiology, to molecular mechanisms controlling cellular function, and all of these tools provide powerful insights into how humans are put together and how our bodies function. Yet, as much as these tools are used to understand how healthy people function, human biologists often stay focussed on how to cure sick people. That is, the proximate value ascribed to human biology research is in its ability to cure disease and improve peoples’ lives. 

In Ecology, our sick patients are heavily impacted and urbanized landscapes. By understanding how natural systems function can provide insights into strategies to improve degraded ecosystems. This value of ecological science manifests itself in shifts in funding and publishing. We now have synthesis centres that focus on the human-environment interaction (e.g., SESYNC). The journals that publish papers that provide applied solutions to ecological and environmental problems (e.g., Journal of Applied Ecology, Frontiers in Ecology and the Environment, etc.) have gained in prominence over the past decade. But more can be done.

We should keep the ‘sick patient’ metaphor in the back of our minds at all times and ask how our scientific endeavours can help improve the health of ecosystems. I was once a graduate student that pursued purely theoretical tests of how ecosystems are put together, and now I am the executive editor of an applied journal. I think that ecologists should feel like they can develop solutions to environmental problems, and that their underlying science gives them a unique perspective to improving the quality of life for our sick patients. 

Where the wild things are: the importance of urban nature

Cities represent our ultimate domination over nature. They are landscapes that are completely modified to meet all of our needs and desires. In cities we drastically change the vegetation, reroute rivers, seal the Earth’s surface in impermeable cement, and often change the chemical composition of the air around us. For most people, this unnatural state of affairs seems completely natural. Its how we grow up.

What we don’t notice is all that is missing. The trees, the birds, and the mammals are largely absent from big cities. But not all cities are equal in this missingness. For those of us that live in cities like Toronto, Nashville, or Sydney, seeing birds and mammals is part of our normal life. In my back yard in Toronto, I am likely to see racoons, skunks, possums, red squirrels, eastern grey squirrels, chipmunks, deer mice, and a plethora of birds, and just down the road, foxes, coyotes, and deer are not uncommon. One morning I heard a ‘thud’ come from our sunroom window, and outside was a stunned red-tailed hawk (he was fine in the end). These cities are evidence that nature can persist and coexist with urban development.

However, there are other cities where nature is almost completely absent. While living in Guangzhou, China I saw just cats, dogs and rats, and barely any birds –shockingly no pigeons. Recently in while in Montpellier, France, it became obvious to Caroline and I (the two EEB & Flow contributors) that besides a small lizard species, pigeons and a few sparrows, we were not going to see any wildlife in the city. Guangzhou and Montpellier are very different cities in terms of size (16 million vs. 300 thousand), density, building height, pollution levels, etc.  But one way they are similar is that they are old. People have living and changing the landscapes in these regions for thousands of years. Of course the same could technically be said of North America and Australia, but the magnitude and intensity of human modification has no parallel in North America and Australia. Long-term intensive human activity removes other species in the long run. Is this the natural endpoint for our younger cities?

Cambridge, England. While quite beautiful, it is a typical old european city with a lot of stone.

Why we should celebrate raccoons

Toronto has a war against the raccoon. To most Torontonians, the raccoon is a plague –vermin that get into garbage cans and pull shingles off of roofs. Their density in Toronto is about 10 times higher than in wild habitats and many people in Toronto support removing them all together.

I have a different stance. We should be celebrating the raccoon. Yes raccoons cause problems; yes they carry disease; yes they damage property; yes their density is unnaturally high. But the same can be said of people (I don’t think I ever caught a flu from a raccoon). If raccoons were to recede to distant wilds and disappear from Toronto altogether, we would be no different than all those other cities where nature has completely lost. Raccoons give hope –hope that nature can flourish under the repressive and cruel dominion of urban centres. Raccoons remind us that nature has a place and can thrive in cities, and that we can share this world. They give me hope that Toronto’s destiny is not prescribed and we are not bound to the same fate as so many other cities.

I have a couple of new Chinese scientists visit my lab each year, and the differences between Toronto and say Beijing or Shanghai could not be more stark for them. To see deer, squirrels and raccoons in the city is a marvel. Every time one of these visitors comments on the wildlife in our city, I am reminded that we are really fortunate and have something that should be cherished.

Raccoon family –not an uncommon sight in Toronto (CCBYgaryjwood) 

Need to rethink urban nature

The problem is that Toronto, and most other cities, is continuing to grow and become more densely packed, making it more difficult for nature to endure. We need to rethink how cities grow and develop, and we need to keep a place for nature. There is no reason why new developments can't accommodate natural elements and green space –this often does not happen in most cities. Singapore is unique in this sense, new public infrastructure projects explicitly incorporate novel green space and infrastructure. I toured green sites there recently and saw a new hospital where it was impossible to tell where the park space ended and the hospital started (see picture below). There I saw patients tending gardens on the roof, nearby residents strolling through the forested courtyards, and turtles, wading birds and a large river monitor in the neighbouring pond. Also, Singapore's new large pump house infrastructure that reduces flooding in the city has a full sloping lawn on the top that is used by picnickers. In most North American cities this type of building would be grey industrial cement with little other function than to house pumps.

Singpore's Khoo Teck Puat hospital -the world's greenest hospital? 

Large old cities devoid of wildlife need not be the natural endpoint for a city.  Smart development and accommodating nature needs to be woven into the tapestry of cities. Toronto’s raccoons are great, and I wouldn’t want to live in a Toronto without them.