Posts Tagged ‘Jeffrey Ling’

Wow.  We had some sunshine this weekend.  Can spring be too far off?  Before we know it, it will be time to start thinking about new plantings.  Is tree planting in your future?

You don’t need me to tell you that trees are important in public spaces.  Their benefits are pretty obvious.   But too often we think we can dig a hole, drop in a tree, and enjoy the shade for years to come.  A walk downtown reveals that trees have a tough time in an urban environment.  Stumps and empty tree wells tell the truth.  If we want the trees in our public spaces to look good after the ribbon-cutting, we need to be more aware of what trees need to survive.  That’s why I asked arborist Jeffrey Ling to talk about what it takes to create and maintain a healthy environment for trees.

Tree in a planter at the United Bank Plaza in Charleston, WV.

 

I first “met” Jeff in a LinkedIn discussion group.  I had been kicking around an idea to create an en pleine air studio for a local museum in a grove of tightly spaced trees.  I was concerned about overcrowding, so I posted a question about it in the discussion group.  Jeff’s responses so impressed me that I knew at some point I should pass along his thoughts.  Yeah, it’s a little technical, but you guys can handle it.  It’s stuff that people who are interested in public spaces need to know.

Here are Jeff’s thoughts…

Nearly every urban site has trees as a part of the design.  Trees provide form and function for a location.  They can be an inhibitor for visual trespass, a blocker of unwanted vistas, and produce valuable shade along with aesthetic interest.  As we all know, trees are a contributor to the overall statement and value of the public space.

What sets trees apart from all other plant selections is the wood.  Trees are unique in this regard.  It is the wood which produces the opportunities and risks for tree planting and tree longevity on a cultured site.

Above the ground, the wood is both descriptive of the species and directive of its character.  Wood is ‘tree engineering’.  Its genetic predetermination is the template to build the organism, yet trees are responsive growers and the shape, texture and plant vigor will be altered by orientation, competition and site management (or mismanagement).

Wood under the ground is even more critical for growth and support.  It is here where we can fall short.  There is no greater disregard for a tree’s potential than when the design places a tree in a space which can not accommodate the needed root zone development.  A general rule is 54 cubic feet of root zone per inch of trunk caliper.  Projecting this out; to grow an 18-inch shade tree one must prescribe a 1,000 cubic foot root zone.  Root zone volume is the first and primary variable for tree size and longevity.

Soil temperature is another constrictor to tree growth and size.  We know that urban landscapes are hotter than suburban or woodland sites.  As soil temperatures rise root function diminishes, and stresses, especially drought stress, increase.  William Graves of Iowa State University reports that when urban soil temperatures are over 90oF, tissue damage follows.

Finally, there’s the issue of water. Nearly all negative effects on urban trees are in one way or another based on water deficiency. While there are drought-tolerant species, in the end, it is a site, not a species issue.

As one who has worked on scores (maybe hundreds) of legacy and historical trees, let me strongly recommend that every designer have an arborist on call who can first assess the condition of existing trees on a given site, both in structure and entropy.  The arborist, as a specialist, can assist the designer in site directed issues with regard to tree growth.  It is a liaison which can produce greater value for the client.

Jeffrey Ling is a registered consulting arborist practicing out of Fort Wayne, Indiana and is the President of Arborwise, Ltd.  Learn more about Jeff and his company at www.arborwise.com.