One of the most common problems urban trees face is having sufficient soil and space to properly grow. Crowded cities make it challenging to mimic the natural environment in which trees thrive. Thanks to emerging green technology, cities are beginning to implement greener practices in construction that are saving cities tree repair costs down the road and creating a healthier setting for trees to grow.Ordinarily when trees are planted in metropolitan settings they are buried under hard surfaces such as sidewalks and roads. These surfaces have to be robust enough to handle heavy vehicles. Naturally, the result of such weight is soil compaction. Soil compaction constricts water, air, and nutrients from reaching the roots, stunting the growth of trees and even leading to structural failures.
In 2007 DeepRoot introduced the Silva cell —the first commercially available soil containment system to be used in construction that supports heavy asphalt surfaces without compacting soil surrounding tree roots — a breakthrough in urban infrastructure.
So how does it work?
The rigid frame is designed like a modular suspended pavement by transferring above ground loads down to a compacted sub-base while the inside of the system is filled with loose soil for roots to access. In addition to the loose soil, the system also acts as a stormwater management system, absorbing runoff and storing a large amount of water, creating an underground rain garden.
While the technology is new and still evolving, there have been more than 500 installations of Silva cells in 10 different countries. The results have been outstanding with reports of healthy tree growth, including longer bud extensions and trees flourishing to full maturity.
Lincoln, Nebraska is participating in the trend with four installations of Silva Cells at construction sites, including near the Arbor Day Foundation headquarter offices.
Is your city installing Silva cells? What other approaches is your city implementing to promote healthy urban and community forests? You may also enjoy reading our How to Save Trees During Construction, a Tree City USA Bulletin.