You Can’t Fool Mother Nature but You Can Understand Her

James Urban, FASLA, noted soil and tree expert, recently gave his talk, You Cannot Fool Mother Nature but You Can Understand Her, at the Arsenal in New York City. Urban is a prolific writer and lecturer on the subject of tree planting and the conditions needed to improve tree performance in urban environments. Urban focused his talk on “eight simple ideas,” all basic steps to yield more productive growth in urban trees. The ideas were driven home by a slideshow containing images from his recent award-winning planting guide and bookshelf mainstay, Up By Roots: Healthy Soils and Trees in the Built Environment. It was refreshing to know that the lecture did not fall on deaf ears as heads of the NYC Parks Department, the ASLA NY Chapter, and New York Restoration Project were all in attendance. If anyone needs to hear Urban’s talk, it would be them.

To Urban, planting trees is “all about the science.” Take a walk down your street and notice the adolescent trees stuffed into the recently curb-cut sidewalk. According to Urban, that is our fatal mistake. “We try all the time [to fool nature] but we never win.” The space below the ground is competing with other urban systems: stormwater structures, utilities, urban compaction systems. These obstacles severely hinder the performance of those adolescent trees, many of which were not even properly selected in the first place. Urban shared his understanding of this paradigm: “Once we have a hypothesis, we tend to give extra weight to any information that supports that hypothesis.” To Urban, this kind of thinking leads to many street trees being planted incorrectly.

Over the past thirty years, Urban has been instrumental in the development of both structural soils and structural cells for use under sidewalk pavement. However, his message has remained and his eight guiding principles to planting trees have as well:

1. Trees need dirt!
2. Plant trees that are native to their urban ecosystem.
3. Can you resolve the conflict between the politics of trees and the planting of trees?
4. There is no free lunch.
5. Get just one tree right.
6. More soil volume please.
7. Harvest stormwater.
8. Improve the nursery stock.

1. Trees need dirt!
According to Urban, New York is actually a relatively easy place to grow trees. To become a functional, mature tree in an urban environment, a tree needs between 800 and 1,200 cubic feet of “good-quality loam soil.” Urban believes that New York City has the space but not the soil.

2. Plant trees that are native to their urban ecosystem.
To further understand this concept the audience was pushed to buy Peter Del Tredici’s, Wild Urban Plants of the Northeast: A Field Guide. No longer are we harking back to the Manahatta planting plan for advice on what to plant on Queens Boulevard. Urban, the consummate pioneer of the urban environment tried to incite the crowd. “Let’s get into it and start figuring it out!” Urban also warned us that in ten years or less we will all be calling nurseries to purchase Ailanthus.

3. Can you resolve the conflict between the politics of trees and the planting of trees?
Urban took this opportunity to speak of the role of the arborist. Currently, certification is relatively easy to obtain. However, as the profession of arborists progresses it needs “serious restrictions.” Making certification more difficult to acquire would promote the profession, putting them on the political map. Arborists could then better join broader political discussions and highlight the importance of trees.

4. There is no free lunch.
Here Urban stressed the idea of compost. His example that “two tons of raw wood only produces one ton of compost” is telling in that he believes there is room to explore this area. He further explains this idea by bashing “the hot item right now,” Bio-Char. After describing Bio-Char as “really bad,” he lightened the assault by clarifying that “it is only good for small amounts of soil.” I wonder if this “simple idea” was an idea at all, or an excuse to diminish the popularity of the charcoal-based soil amendment.

5. Get just one tree right.
In a checklist for tree design, one requirement is to understand the root area index (RAI), the calculation determining the correlation between the root and the surface area. To explain this, Urban used an image of a wine glass standing on a dinner plate. The dinner plate, representing the soil volume and the wine glass base, the trunk flare, are basic visuals of how simple a successful planting can be.

6. More soil please.
Again Urban stressed the importance of understanding soils and the surroundings. Soil can be understood as the community of vegetated and urban systems surrounding the planting site. Urban explained the efficiency of his structural cells compared to that of constructed soils (Cu soils). One attendee, an expert and supplier of Cu soils, vehemently disagreed. He argued that the structural rock matrix that makes up the load bearing component of Cu soils do not inversely affect the performance of tree roots as Urban suggested. Not wanting to get into a fight over the success of his inventions, Urban explained, “I’m almost done with the Cu slide…actually, I’ve been done with the Cu slide since 2003.”

7. Harvest stormwater.
“When designing systems it’s important to allow nature to guide us in protecting our natural systems from floatables, hydrocarbons, chemical pollutants, and runoff toxins.” In the green infrastructure overhaul of New York City, large trees will play an important role in the solution and have the ability to “store and process massive amounts of stormwater both in their roots and leaves.”

8. Improve nursery stock.
Nursery stock, in the age of the New York City’s Million Trees Project, have become a hot topic. Tree growth can be determined before a tree is even planted if a basic understanding of the stock is obtained. There are many issues concerning healthy plant growth at nurseries. Proper limbing, pruning, watering, drainage, sunlight, soil volume, and basic organization are all things to consider when visiting a nursery for healthy plants. However, the number one issue is container plants. “We need to stop buying container trees. It’s an unfixable problem!” The girdling of roots has no remedy and their trees have no chance of reaching their potential.

Much of what James Urban discussed in his lecture seems to touch on the ideas of publicity. Yes, the science of tree planting is essential to success but so are “politics.” Urban reiterated this idea by empowering key figures in the crowd.”The Parks Department, the City of New York, and New York Restoration Project need to put pressure on nurseries!” It’s Urban’s hope that New York City will become the benchmark for intelligent street tree planting.

This guest post is by Tyler Silvestro, a master’s degree candidate at the City College of New York (CUNY), and writer for The Architect’s Newspaper.  

Image credit: Silva Cell / Deeproot

2 thoughts on “You Can’t Fool Mother Nature but You Can Understand Her

  1. CW Glaeser 04/21/2012 / 4:23 pm

    Tyler, thanks for your reporting on the Jim Urban talk.
    But I may add on point number 3. Can you resolve the conflict between the politics of trees and the planting of trees?, Jim differentiated between the base line foundational certified arborist (of which there are many) and those that are certified and practice the profession know as Consulting Arborist (CA). It is the CA with his/her years of experience, a broad arboricultural skill set and a full understanding of science of arboriculture (as well as soils) who is the go-to person on the tree & landscape matters that Jim was addressing during that part of his talk.

  2. Urban Choreography 04/23/2012 / 2:50 am

    Reblogged this on Urban Choreography and commented:
    With the emphasis on putting the green in Greenstar and LEED building discourse, information on what it actually takes to have urban trees is sorely needed, James Urban’s book was manna to me when I first read it and its message – “Trees need Soil – not dirt” in the words of Elaine Ingam of Soil Food web: Dirt is something you find under your fingernails – soil much more than that – and trees need lots of it to grow to a decent size and maintain their health over time.

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