The root of the problem

Roots are major organs that are essential to tree health.  However, they are often overlooked as construction, foot traffic or other soil compaction issues permanently damage a tree.  Where are the roots anyway?  How far out do they extend so that damage can be avoided? Can we manage roots in an urban environment full of sidewalks and pavement?  Research may show some insight to this hidden underground world.

Traditionally, a typical tree root system illustration would show a central tap root penetrating deep into the soil with side roots and fine roots extending out in all directions to the edge of the branch reach.    Some research suggests that in fact taproots may be absent depending on the species and other conditions.  As an example, oaks may have a taproot while maples will not.  Some taproots are cut at planting and are absent.  Urban trees in compacted soil often do not have a taproot.  It was also found that side or lateral roots are situated well outside the drip line.  In fact, many trees were found to have a root spread of three times the spread of the branches with most of the fine roots found only in the top twelve inches of soil - many of these roots were found in the top two to three inches.  Research showed that a Southern magnolia, for instance, had roots out to 3.8 times the drip line.

So what are the implications for working around trees and planning for root issues?  Trees that may appear to be well protected can still be damaged because the roots go so far out beyond the drip line.  This could influence construction site work, foot traffic patterns around urban trees and other considerations.  Trees that appear fine today may show signs of decline and death in subsequent years.  Can you imagine what the tree you just planted will look like in thirty, forty or fifty years from now?  Will it interfere with a sidewalk, a driveway or underground utilities?  In brief, trees roots in urban areas can be managed with techniques such as root barriers, engineered/structural soil, channeling roots, etc.  Florida Certified Arborists are good resources for assistance with this effort and can be located at the Florida International Society of Arboriculture - http://www.floridaisa.org/.

Tread carefully around trees - their roots are essential for structural support and as organs to gather nutrients and water.  They must be protected and managed for the long-term health and safety of our urban forests. For more information on the best management practices for planting trees, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer.  Don't forget to visit our other County Plant Clinics in the area.  Please check this link for a complete list of site locations, dates and times - http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf.

Resources:

Gilman, E. F. (2014) Root growth on urban trees. The University of Florida Cooperative Extension Service, IFAS - http://hort.ifas.ufl.edu/woody/roots.shtml

Gilman, E. F. (2005) Planting Trees in Landscapes. http://hort.ifas.ufl.edu/woody/planting/rootgrowthintro.htm.  The University of Florida Extension Service, IFAS.

Gilman, E. F. (2011) Dispelling Misperceptions About Trees. The University of Florida Cooperative Extension Service, IFAS.

Gilman, E. F. (2011) Where Are Tree Roots?  The University of Florida Cooperative Extension Service, IFAS.

Gilman, E. F. Gilman, E. F. (2002) Site Evaluation Form for Selecting the Right Tree for Your Planting Site, the University of Florida Cooperative Extension Service.