In this posting I share findings from a paper I wrote on inequalities in the distribution of street trees across neighborhoods of differing socioeconomic level in Bogotá,  Colombia.  Yes, it's quite a mouthful. 
    My research generated the first set of published data on street-tree inequality in any developing-world city, conclusively demonstrating the green divide in Bogotá and providing a basic model for street-tree equity studies in other cities around the world. 

     In all my writing, the importance of trees in creating a quality urban life has been a constant theme.  The benefits of trees, especially street trees, range from environmental improvements (urban cooling and cleaner air) to social benefits (stress reduction and neighborhood cohesion).  Countless studies have documented the transformative power of urban trees.  And what's more, most people would agree that trees are beautiful.   But despite their importance, trees are not a resource shared equally in most cities of the world. 

    Even a brief stay in Bogotá will make one aware of the dramatic change in
the look of streets as one moves across socioeconomic lines.  The change is not striking simply in respect to the style and quality of home and street construction, but equally dramatic in the almost complete lack of street trees and vegetation in
neighborhoods at the lower socioeconomic levels. 

    Bogota is a city officially divided into socioeconomic units called estrato (strata) numbered from 1 to 6.  Estratos 5 and 6 represent the wealthiest neighborhoods, and 1 and 2 the poorest.  
    To document the tree disparities across estrato, I conducted a tree survey with a random sampling of 30 streets in the wealthiest part of the city (estratos 5 and 6) and 30 in the poorest parts of the city (estratos 1 and 2).  At left is a chart showing the data.  The survey results makes it clear that the tree gap across socioeconomic lines in Bogotá is uniform and stark.  Generally speaking, the streets in the lowest estrato of Bogotá are barren, while the streets in the wealthy neighborhoods have a healthy canopy of trees. 

    But why does this green divide exist?  The observant visitor to Bogotá will notice that a formidable barrier to street-tree planting exists in much of the city:  the changing structure of the streets as one moves from the higher estratos to the lower.  This change can be very abrupt. Simply crossing a single street can bring you into a markedly different environment.  One key to the difference is the structure of sidewalks and the allocation (or not) of a planting median between the sidewalk and street.  The lack of a planting median is one of the hallmarks of the lower estratos in Bogotá.  Not only are the structure of the houses different, but the streets in the lower strata are almost always without a green median between the sidewalk and the street, and hence are without room for trees.  They are urban deserts by design. 

    The inferior design of low-estrato streets in Bogotá has resulted from mass migration into the city under the neglectful watch of dysfunctional city and national governments. In the period from 1960 to 2012, Bogotá's population increased from slightly over 1 million inhabitants to nearly 10 million today.  During much of this same period, Bogotá's government was ill equipped in terms of resources, organization, and capabilities (and interest, many would say) to manage the mass influx.  Large swathes of this city were, therefore, developed without any government regulation.  With no goverment involvement, private 'pirate' developers created most lower-class neighborhoods in this city.  To maximize their profits and keep costs low, land was divided into as many lots as possible, leaving only a bare minimum of space for public amenities.  Streets in these neighborhoods are very narrow, and sidewalks, where they exist, are extremely narrow.  
    The problem of the structure of low-strata neighborhoods hangs heavily over efforts to improve the urban environment for the poor, and in particular efforts to increase street-tree cover in Bogotá. As nearly half of Bogotá's
neighborhoods arose from pirate developments, it seems to many that these areas will be permanently treeless.  A rebalancing of the tree population in Bogotá’s streets will require strong and effective government and a commitment to focus on the streets that dominate the lives of more than half the population of this city.  
    To get things moving, highly visible pilot projects should be launched, in conjunction with community organization and green education campaigns, to demonstrate the great improvements in quality of life that green streets can bring.  As the streets of most neighborhoods don’t provide much space for trees, innovative and low-cost solutions that provide some of the benefits of trees may be adopted, such as green roofs and vine-covered walls and canopies.  However, in many cases as streets are paved for the first time, or repaved, redesigns can be implemented that include planting spaces for trees.  In many areas, streets can be pedestrianized, which would allow ample space for canopy-forming trees to be planted.   Successful projects showing how city life can be transformed will lead to further interest and belief by the public in the benefits of tree-lined streets.  This dynamic city, with its mild and favorable climate, has what it takes to become one of the greenest and most beautiful in South America.

In this posting I will discuss inequality (a very hot topic in the news today) and its relationship to urban greening.  Inequality in a society is popularly measured by the Gini Index.  If you look at the chart below, representing data from the Gini Index, the darker blue a country is, the more evenly distributed its wealth is.  Countries such as Norway, Sweden, Germany, South Korea and Australia are among the most equal in the world.  Next in line among the lighter blue countries come places such as Canada, France, Japan and the 'rest' of the developed world.  In fainter blue we find countries such as China and Russia  Moving down the scale into the tans and oranges, we arrive in Latin America, the most unequal region in the world.  What's striking is the inclusion of the U.S. in this region of inequality, with a GINI coefficient on par with that of Mexico and Argentina.  Colombia, Brazil and Chile have even more severe inequality.  South Africa, still dealing with the legacy of apartheid, has the most unequal society of any major country in the world.

Inequality by itself is something that any normal society has and requires.   Without inequality of capabilities, efforts and rewards, the modern economy wouldn't function.  But severe inequality, as we see in the U.S. and Latin America, has negative side effects  that weigh heavily on societies at large.  These effects include high crime and homicide rates (and the concomitant high incarceration rates), high teenage pregnancy rates, poor educational performance (and a resulting oversupply of unskilled and shortage of skilled labor), a distrust in institutions (both government and private), decreased effective demand (a lowering of overall consumption in the market), mental and physical health problems, and a poor natural environment. 
When people on the bottom feel disenfranchised, that their extra effort won't pay off because upward mobility seems impossible or extremely unlikely, social cohesion and stability suffer. As an American living in Colombia, I am particularly fascinated by the inequality debate taking place in the United States now.  It all seems so familiar, and so relevant for Colombia, as well.  On the whole, gross inequality is not only bad for the poor.  It's bad for everyone. 

The United States is a country of great wealth.  But there's nothing unique about the phenomenon of wealth and its associated beautiful neighborhoods, excellent schools and high quality of life.  Nearly every country and major city in the world exhibit these phenomena to some extent.  Even generally unpleasant places I've come to know, such as Lagos, Nigeria, have islands of extreme wealth and privilege.  What is, on the contrary, relatively unusual are places where the gap between the wealthy and the poor is not so strikingly evident, where the urban environment doesn't shift dramatically when moving from one economic reality to another, where the poor aren't confined to a dramatically inferior quality of life and to circumstances that are hugely deterministic of how their life will proceed.     

Bogotá provides an excellent example of the typical pattern in middle income countries.   Unlike a very poor city such as Lagos, Bogotá has vast areas of impressive wealth, with hundreds of thousands, if not over a million, of its eight million residents enjoying a living standard which most New Yorkers or Tokyoites might envy.  If we could isolate the wealthy neighborhoods of Bogotá and consolidate them into a separate city, I'm rather sure it would rank among the wealthiest and best educated in the world.  

And not only is the abundance impressive.  So too are the opportunities for those at the top.  If you are from a wealthy family in Bogotá, odds are that you have an excellent education, high-quality medical and dental care, a network of influential connections - and an excellent job paying a rich world salary with a social and cultural life to match.  You will be missing little that your wealthy peers in Europe or the US enjoy.  There is a pride among the well-to.do in Bogotá.  They have created a beautiful world in which to live.  

And the gross inequality of Bogotá, not often visible from the confines of the wealthier districts, adds to the luxurious life that the upper classes here live.  Abundant cheap labor makes life convenient, relaxing and safe.  There are maids who cook, clean and care for children, doormen who guard the countless luxury apartment buildings, and a whole array of other people providing services at very low cost to make life almost care-free by the standards of the average person in the so-called rich world.  The upper classes here have very little interest of moving to Europe or the US, except possibly in pursuit of an education - after which they tend to come home.   

But the peace of mind of this upper class must be contingent upon an ability to ignore the terrible poverty and hardships that so much of the population here faces - and to forget the risks historically associated with it.  Maybe they tell themselves that in a rapidly growing economy such as that of Colombia (Colombia is growing faster than the US ever did in it's developmental period) there are so many opportunities that's it just a matter of hard work and responsibility to create a comfortable life and become comfortably middle or upper class.  It's a comforting thought that shows very little understanding of the reality of being poor, hungry, poorly educated and with no connections and none of the advantages that come with birth into privilege.  In my time here in Colombia I've come to know people on both sides of the divide, and I see how insurmountable the barriers are to those unfortunate enough to be born on the wrong side of the tracks.  

I feel that the U.S. has something to learn from the example of countries such as Colombia.  We seem to have forgotten the course of our own development, from a country with extreme poverty and inequality to one with a large middle class and, until the last decades, diminishing inequality and poverty.  When Americans nostalgically look back to a better era, often it is the 1950s and 60s.  The economy was strong, unemployment was low, foreign competition was weak, and there was a perception of boundless opportunities and certainly a feeling that you could have a better life than your parents and grandparents.  This was the time of the 'Great Compression', a period when income inequality was at an all-time low in US history.   This period extended through the early 1980s.  See the chart below.    

The last three decades have put the US on a reverse course to return us to the inequality of 100 years ago.  This brings me back to what I see as the converging nature of US and Latin American societies.  Americans have typically looked down on Latin America as a backward region with terrible inequality and poverty, high crime rates, low levels of educational attainment, and dysfunctional government.  But when these same issues are affecting us at home, why do so many turn a blind eye? 

It might be interesting to make a comparison of the US of 100 years ago with the Colombia of today.  This was the U.S. of small, laissez-faire government and few social protections.  It was a country of new industries, rising to economic preeminence in the world.  However, a comparison with the Colombia of today is not flattering.  The US economic growth rate was 50% lower, literacy rates substantially lower, health care coverage and life expectancy far behind, and educational attainment and incomes (in constant dollar terms) much lower.  This may have been a glorious era in the eyes of some historians, but it was no golden age for the average American.  

A return to high-level inequality explains some of the parallels between the United States and Latin American societies today.  As I've written above, both the U.S. and Latin America have strikingly high homicide rates, high levels of incarceration (the U.S. leads the world), low social cohesion among differing groups (socioeconomic, religious, racial, political, etc), a lack of trust in public institutions, low high school graduation rates, inaccessibility for many to higher education, and a perception among some groups that respect can't be earned without recourse to violence. 

I, for one, am not comfortable with America slipping into the same league as Latin American countries.  After my sojourn in Colombia, I plan to return to the United States because I don't want to spend the rest of my life in a country with deep social problems and the instability this entails.  Americans in the past have taken pride in the stark divide between the U.S. and our neighbors to the south.  There was (and still is) an air of moral superiority, a belief that our society is fundamentally better.  Will it continue to be? On our present trajectory, it's doubtful.      

Inequality in both Colombia and the U.S. has a green footprint.  In fact, the green divide might serve as a great marker of social inequality.  It's easy to see it in the tree-lined streets and well-groomed parks of wealthy districts and the barren streets and abandoned lots of poor areas - as evident in New York or Los Angeles as it is in Bogotá.      
There is a lot of research establishing the negative consequences resulting from a lack of trees and green space in a neighborhood, ranging from the physical (more polluted air and a stronger heat island effect) to the psychological (lower general sense of well being and more stress).  Green in the public space is one example of a common human need that is often not being met in grossly unequal societies - just like good public schools and security.  Efforts to address gross inequality can start with initiatives to re-balance public goods, to make the experience of walking down a street in Soacha feel not so utterly different from the experience of walking down the street in Chico (a wealthy neighborhood of Bogotá), or being in a public school in the south Bronx not so different from attending a public school in Westchester County (a wealthy suburban area of New York). 

A holistic city vision and plan for streets, green spaces and green transport is a foundation for high-quality city life.  But what exactly is it that makes for an urban landscape that supports the good life?  In this posting I focus on mobility, a critical key to urban health.  Mobility in a sophisticated urban life is the ability for anyone to get around a city safely, quickly, and with little or no stress.       
In most cities today, a minority has a stranglehold on the space allocated to transport.  This minority (and it is a minority in most cities of the world) is city dwellers who use cars.  Big-city space is scarce, and with one person in a car taking up an area that could accommodate dozens in a bus or streetcar, or maybe 6 on bicycles, cars tend to overwhelm urban infrastructure and rob everyone of quality mobility.
Large cities around the world are looking for solutions to the mobility problem, and those that have succeeded have almost invariably placed limits on the automobile.  These successful cities have built accessible and efficient public transport systems.  Some have gone a step further, making bicycling a safe and viable option for all urban residents, revolutionizing urban life in unexpectedly nice ways.  Innovative street design, incorporating bicycle paths, is central to the plans of any city aiming for the highest quality of urban life.

Bicycle paths take many forms, but can simply be defined as designated lanes for bicycle use.  Ideally, these paths are segregated from automobile and other traffic, although the reality in dense urban areas is that bicycle lanes are often shared and/or just added as an afterthought to existing streets with no separation from vehicular traffic.  
The development of bicycle infrastructure (but not bicycle usage) tends to closely follow socioeconomic indicators such as high income and high education.  The countries best known for providing excellent paths for bicyclists include the Netherlands, Denmark, and Germany.  Cities with a similar reputation include Montreal, Portland, Perth, Barcelona, and even New York as of late.  But one city ranked near the top for its biking infrastructure is a bit out of place in this elite group of wealthy countries and cities:  Bogotá, the capital of Colombia.  Bogotá consistently ranks among the top ten cities globally for biking, and it provides a model for many other cities in the developing world.  There's a fascinating history behind Bogotá's unlikely rise, and I recommend you take a look at Martin Herrndorf's blog on this topic here.

Bogotá, although nestled in the high Andes and with an impressive mountain backdrop, is generally a flat city that is ideal for bicycle transport.  The planners of the cicloruta (Spanish for bike path) system in Bogotá have used this flatness, and the city's grid pattern, to make for an extensive system (over 300km) of separated bike paths that efficiently take you just about anywhere in the city. I have ridden across nearly half the system in my five months in Bogotá, and generally the experience has been excellent.  The system is well-maintained, and despite the rainy climate and sometimes bad air pollution along major roads, it's a wonderful way to get around the city.  
The paths here are used for leisure and exercise, general transport, and have a surprising number of people delivering goods of great variety - from hot meals to metal piping.  I could just as easily exchange the word 'people' with 'men', however, when describing users of the ciclorutas.  My impression is that male bikers greatly outnumber female bikers, especially on weekdays.  I can only speculate as to why (maybe security concerns or an idea that it's not a feminine way to get around).  A recent article in Transportation Alternatives gives some answers to a similar question in New York City. 
Finally let me clarify that despite its extensiveness the cicloruta system in Bogotá is not, in my observations, used like systems in Amsterdam and Copenhagen as a primary mode of transport for office workers.  But this is a topic for another posting.    

Despite my optimism about biking in  Bogotá, it does present certain  challenges and frustrations.  In cities such as Amsterdam, with a long history of urban bicycling, a common culture of biking has developed wherein every Dutch person seems to  instinctively know the basic rules.  Pedestrians and vehicles usually stay out of bike lanes, bicyclists signal to each other to indicate turns, and a general level of biking civility is maintained.  In Bogotá its more of a free-for-all.  Pedestrians routinely walk in bike lanes, cars and other vehicles (and vendor carts) block the routes, and in any situation where a bicyclist needs to enter a proper street, it can be dangerous.  There is a general lack of respect for bicyclists (and pedestrians) by drivers in this city.  Cars do not tend to slow down and yield to bicycles - even if there is a stop sign demanding this.  What's needed here is more verkehrsberuhigung, a wonderful compound German word for traffic calming, a concept the embraces the view that streets are public spaces that should be shared equally by all users.  Typical traffic calming strategies include speed bumps, curb extensions, and signs indicating pedestrian/bicycle crossing areas.  

In addition to its ciclorutas, there are additional opportunities for bicyclists in this huge metropolis.  Every Sunday and national holiday Bogotá closes over 120km of city streets to traffic and from 7 a.m. to 2 p.m. the streets are the domain of bicyclists, pedestrians, rollerbladers and others luxuriating in the usually off-limits expanses of space devoted to the automobile.  This practice is called ciclovia and the city estimates it provides exhaust-free exercise space for over 1 million people and it is hugely popular here.  There are few better ways to get in touch with the local scene in Bogotá than to ride or stroll down one of the closed streets on a Sunday morning.   It's a festive occasion and a whole industry has arisen to cater to the needs of those out on the streets.  There are well-organized vendors selling drinks, fruit and other snacks and bicycle repair stands lining the streets.  Ciclovia is a practice that should be adopted by cities all over the world, and it's not isolated to Bogotá.  I've seen a similar, if less well-organized, program in Guadalajara, Mexico.   

For my work with CitiNature, the ciclorutas of Bogotá provide a natural space for projects, as they are inconsistently greened.  Biking under a green canopy adds visual pleasure to a ride.  Trees give a fresh smell to the air, provide protection from the tropical sun and act as a buffer with traffic.  In some areas, the vegetation along the paths is lush, in others patchy or nonexistent.  There are many spaces that may have once been planted with trees and bushes that today are empty - easy targets for a greening project.  .  
There are also many un-pruned trees that  obstruct bicyclists.  It's not uncommon to have to duck as you ride to pass through some areas.  I envision a project wherein CitiNature will help train volunteer pruners to do this job, as is done in New York City.     

The opportunities open to bicyclists in Bogotá add to the quality of life in this city and with increased cycling - especially for commuting to work - the physical environment of Bogotá can further improve.  
To purchase a bike in Bogotá and start making a difference, check out Martin's excellent recommendations.  

Announcements of trips to Colombia, and Bogotá its capital, are generally followed by quizzical glances, questions about safety (and sanity), and repetitions of well-worn cliches about the drug trade.  People are skeptical about Colombia.  After more than three months of living here, I must say that Bogotá is one of the most misunderstood and underrated capitals in the world.  It has a dramatic setting high in the Andes, with a lush range of the mountains running right alongside.  It's a city of grand scale moving rapidly away from a past of violence and urban chaos into a period of greater safety and urban renewal.  And there's an infectious energy in the air that's hard not to succumb to.  

I came to Bogotá to consider it as a site for future projects with CitiNature and soon after arrival I was convinced that this was a place with which I wanted to engage and put down some roots.  In this blog posting I'll give a general overview of the city's allure to an urban greening activist.    

Three things sum up my excitement about Bogotá: 1) its positive trajectory; 2) an ideal climate; 
3) its expansive scale.    

Bogotá is not an ancient colonial city (although it does have a beautiful historic center), but instead a modern city with an orientation towards the future.  In many parts you could easily mistake yourself for being in newer districts of a European city.  And the similarities are not skin deep.  Bogotá has one of the most extensive systems of bicycle paths in the world (over 300km of paths and growing), a rapidly expanding express bus system (almost like a metro) called the Transmilenio, a government  intent on improving the infrastructure for pedestrians (there are carefully laid brick pedestrian pavements in many areas of the city now), and a cafe culture unlike I've seen anywhere else in the western hemisphere. It's not a city looking back.  

The climate in Bogotá is reminiscent of a Scandinavian summer - and this climate is year-round, shifting only through periods of more or less rain.  Nights are quite cool, but the strong sun warms the city quickly in the mornings.  With abundant rainfall and mild temperatures, Bogotá should be a mecca for gardeners.  This is a city of lush green lawns, blossoming flowers, and hundreds of parks.  Gardening in the nicer parts of town tends to be done by professional gardeners and they do beautiful work with an incredible range of plants that this permanently temperate climate allows.  

For people in search of a project, Bogotá is a city of enticing opportunities.  As might be expected in the 4th largest city in Latin America, Bogotá boasts vast areas of impressive wealth shadowed by neighborhoods less opulent, and large areas of real and relative poverty.  Some 30% of the population officially live below the poverty line.  The city epitomizes the global correlation between wealth and "green."  The wealthier neighborhoods of Bogotá are generously supplied with parks and the streets lined with trees and bushes.  They are wrapped in green, from gardens spilling over high-rise terraces to meticulously manicured landscapes.  The rich in Bogotá know what they've got: the perfect climate for exuberant vegetation.  And it is stunningly beautiful.  

Move a bit to the west from the wealth along the base of the mountains (or south from the newer districts in the north), however, and things start to change, sometimes abruptly.  Areas that previously were solidly middle class or wealthy have obviously been in decline for some time, I imagine due to the violence this city experienced in the not too distant past.  Single homes are much harder to protect than high-rises with doormen and the population with money may have largely migrated to new areas of high density.    Once charming neighborhoods are slowly crumbling through benign neglect, and previously elegant parks and streets are losing their trees and bushes.  Few seem to care about maintaining them.  Some streets have entirely lost their trees.  In the poorer neighborhoods there may never have been trees in the first place.  

But as security has increased, the possibilities for urban renewal are endless.  There are a surprising number of streets lined with architecture that might be right at home in the hearts of European cities.  Older neighborhoods surrounding parks seem only to need the right spark for rejuvenation efforts to begin.  I'm of the opinion that this is the time to be in Bogotá and be one of those sparks that brings this city closer to reaching its potential as the most lovely and livable in South America.  And as an urban greening advocate, the low-hanging fruit are in abundance.  Streets and parks that have lost their trees could rapidly be replanted.  As the climate is so benign here, with ample rainfall, the typical losses associated with urban tree planting would be minimized.  A green revolution is in the offing, and I want to be a part of it. 

Below are a few more pictures of the characteristic brick architecture in neglected areas of Bogotá, something I hadn't expected to find in South America.  

This initial snapshot of Bogotá wouldn't be complete without a few pictures of the beautiful historic center, which follow below.  

In the following weeks and months I will be reporting more on Bogotá and CitiNature's plans here.  I recommend to anyone who hasn't been to Colombia to consider putting it on your agenda.  It is a rare jewel of a country generally uncrowded by tourists.