The Gift of Greenery: Could Every Block Have a "City Garden"?

Downtown's Citygarden has been very well-received--almost universally so. A two-block segment of the Gateway Mall transformed from passive (read: boring) green space into a magnificent sculpture garden and public space. The metamorphosis came at a cost--$25 million in design and construction alone. The Gateway Foundation picked up the tab.

On the foundation's website, there is a list of projects and initiatives that the foundation has either contributed to or created. You can thank Gateway for St. Louis's three water towers' dramatic lighting, not to mention minor city landmarks like the Arch and Old Courthouse. They helped to renovate Penrose Park in North City, as well. Still, Citygarden is their crowning achievement, their greatest gift yet to the city.

I couldn't help but marvel at the construction process of Citygarden itself. Almost overnight, some worn patches of grass became lush lawns home to new and relatively mature trees. No thin, weakling trees that would take years, perhaps decades, to blossom into proper shade trees--if they survived at all.

I can't help but wonder if the Gateway Foundation could help certain St. Louis neighborhoods overcome a fatal urban design flaw: treelessness. Treelessness need not be taken literally; some blocks in certain neighborhood have quite a few trees, but they're often unhealthy, ill-placed, or simply, there just aren't enough of them.

Trees are so vital to an urban landscape that New York City, to name just one city, has conducted a census of them (the count you ask? 592,130) and a plan to increase their numbers. Of specific interest to me is the "benefits" section explaining why trees are important.

First, this note:  

Benefits are directly linked to tree size. The environmental benefits of trees arise from respiration and transpiration – the biological processes by which trees breathe and absorb water from the environment. Because these processes involve interactions between a tree’s leaves, the environment, and the atmosphere, the benefits increase as trees grow in size. In general, the larger a tree, the more canopy cover and leaf surface area (the total area of the leaf spread) it has.

This list of benefits is so sensible and actionable that I will post each segment in its entirety:

Air Quality Improvement. Leaves absorb gaseous pollutants (carbon dioxide, nitrogen dioxide, and sulfur dioxide), and capture air-borne particles including dirt, dust and soot. Trees also prevent the release of many airborne pollutants by reducing energy generation. Ground level ozone, a contributor to greenhouse gas formation, is reduced through the tree’s ability to lower air temperatures.
ANNUAL BENEFIT VALUE: TO NYC: $5.3 MILLION

Energy Savings. Trees provide shade, reducing the demand for electricity for cooling in the summer. Trees also reduce wind speeds, slowing the loss of heat from interior spaces during the winter. Trees cool the air through the process of transpiration, where moisture is converted to water vapor. An estimate for energy usage for every building in NYC was derived from data on building age, tree shading effects, and local climate. This estimate was drawn with two scenarios—with and without street trees—in order to show the difference in the resulting energy use. Local energy prices were then used to calculate the value of the impact of trees on building energy use.
ANNUAL BENEFIT VALUE TO NYC: $27.8 MILLION


Carbon Dioxide (CO2). Trees indirectly reduce emissions of CO2 from power plants by reducing building energy use. Also as trees grow, they remove CO2 from the atmosphere and store it in woody plant tissue. At the same time, trees release CO2 as they decompose. These releases are subtracted from the total amount of CO2 avoided from power generation and absorbed by tree growth to calculate the net CO2 benefit.
ANNUAL BENEFIT VALUE TO NYC: $754,947

Reducing Stormwater Runoff. Trees help reduce flooding and improve water quality, as runoff flowing over impervious surfaces picks up contaminants including oil and metals. Trees intercept rain on their leaf, branch and stem surfaces and by absorbing water through their roots. The water that trees intercept in NYC each year was calculated using local rainfall data.
ANNUAL BENEFIT VALUE TO NYC: $36 MILLION

Property Value and Other Benefits. Research has shown that homes with a tree in front sell for almost 1 percent more than similar homes without trees. The difference in sale price indirectly reflects the value buyers place on trees and their more intangible benefits, such as aesthetics. This difference was applied to the median New York City home resale price ($537,300) to calculate the total value.
ANNUAL BENEFIT VALUE TO NYC: $52 MILLION

TOTAL ANNUAL BENEFIT TO NYC: $122 MILLION

Clearly, street trees in urban areas are necessary for the city's natural--and built--environments. Yet some of our neighborhoods aren't receiving these benefits.


Let's look at a neighborhood that is among my favorite in the city--Benton Park West. Tree coverage is passable in some places, non-existent in too many others. Check out the 2700 block of Utah Street for a good example of the conditions of the neighborhood:

 What we have here is actually a nice historic blockface typical of the neighborhood. But it looks unnecessarily barren without a proper line of street trees (it also feels barren when you're walking down a sidewalk in summer weather, baking atop unprotected pavement). This should be an in-demand block based on housing stock and location alone. 


Let's look at a street in Benton Park proper, some half mile away from the view we see above. This is the 2900 block of Lemp.

2900 Lemp is not a perfectly planted block by any means, but is similar in most respects to 2700 Utah--historic buildings, just about the same street width and setback, etc. Yet 2900 Lemp is shaded and inviting.


If our lower income neighborhoods have fewer trees, which I believe, in general, is true, then wouldn't planting some mature trees give them a leg up? As demonstrated in the New York City study, trees save households on energy costs and raise property values. Wouldn't it be great if the Gateway Foundation and their Citygarden partner the Missouri Botanical Garden could donate trees to neighborhoods such as Hyde Park and Benton Park West? Again, the trees have to be large to have an effect. Yet a mature tree costs a lot of money. This source says that a locally-available species of tree aged 7-10 years will run you at least $200 a pop. 

Still, a $25 million program focusing on a few neighborhoods that need these trees could see the planting of 125,000 trees if the $200 figure held true (not counting the costs of planting and maintenance). That would be equivalent to 20 percent of the entire city of New York's stock that that city has counted! Passing over some neighborhoods that already have excellent tree coverage (Tower Grove East in parts, St. Louis Hills nearly in its entirety), such a program to establish these citywide "City Gardens" could confer incredible benefits on the recipient neighborhoods (again, see the NYC study). And it should be noted that green projects--tree planting, park renovations, etc.--are among the least controversial projects that a philanthropic foundation like Gateway can put their name to. That said, they're also much needed and do a great service to our city.

Would the Gateway Foundation/Missouri Botanical Garden be willing to plant City Gardens--also known as full streetscapes of mature trees-- across St. Louis?