With the emphasis on putting the green in Greenstar and LEED building discourse, information on what it actually takes to have decent large urban trees is sorely needed, James Urban’s book was manna to me when I first read it and it’s 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.
Originally posted on The Dirt:
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: