Emerging Tech Addresses Root Girdling

TreesROI™ is hoping to provide trees with better chances for longevity.

By Marie Ambusk
From the October 2023 Issue


As everyone knows, planting trees is an important means of combatting climate change and urban heat islands, as well as simply enhancing the aesthetics of a landscape. But unfortunately, tree planting—particularly in urban areas where they are most needed— has a high failure rate.

Simply google “tree planting failure” and you’ll find a plethora of studies devoted to the issue. Here are just a few:

Preliminary test setup in Ambusk’s garage lab – using 2700 MHz GPR, 1 cm scan slices at each rotation of the tree container. Ideally, the GPR would spin around the tree! (Photo: TreesROI/Ambusk)
  • A 1990 study by David J. Nowak of the U.S. Forest Service reported that 34% of trees planted along a major boulevard extending from Berkeley to Oakland, CA were either dead or removed after two years.
  • Data from 2021 puts the estimated probability of an urban tree surviving 35 years to be about 35% (± 8.6%); survival of a rural tree is about 44% (± 4.5%), according to Smith, Dearborn, and Hutyra.
  • According to American Forests, the U.S. is currently losing one tree for every two trees “established” (established means planted or naturally regenerated). The loss is mainly due to extreme weather events, insects and diseases; trees being removed for buildings; and improper planting practices.

While there’s much of the above that we can’t control, we can improve our planting practices by selecting trees with the best chances of survival. Trees grow slowly. The time lost when they fail — be it 10 years or 20 years — can never be recovered.

Root Of The Issue

As founder, CEO, and principal investigator of TreesROI™, I am in the business of helping “Grow Better Trees” through my small Vermont tech startup. (TreesROI is focused on fixing the problem at the “Root Of It” and improving the “Return On Investment,” a meaningful double entendre.) The story of what inspired my 20-year adventure as the leader of this research project is filled with learning, failing, curiosity, and the belief that any good problem can be solved with science, technology, persistence, a lot of work, and a little luck.

You could also say that I am “the pissed-off customer whose young trees mysteriously died.” Around 2003, many young street trees in my neighborhood died from root collar disorder — a term that was new to me at the time. When I asked how to avoid that problem with the replacement trees, I was told, “Lady, you get what you get.”

Over the years, I studied how trees grow, why they die, and how we could possibly influence their ability to thrive and live to maturity in the urban landscape. Among other things, I’ve determined that it is a noble gesture to consider that we could grow commercial trees in a nursery with roots like Nature intended.

Think about it: the only thing connecting the largest plants on Earth to the Earth are the roots. So, unless we plant bare-root stock, every tree delivered from a grower is in a container of some kind. While this problem is an unintended consequence, when trees are planted with serious root system defects, many will die before they grow large enough to realize their intended benefits. There is simply not enough room in a container to allow tree roots to grow properly for very long. It’s a timing game.

Root Girdling
The stem of a 20-year-old linden tree has grown in girth to become girdled by dozens of circling roots that imprinted the container during production. The tree is now strangled by its own roots.

Several container-grown trees are ready for testing. (Photos: TreesROI/Ambusk)

It’s true there are many causes for young urban trees to die, and tree roots are not perfect. We are not promoting the idea that tree root systems can or should be perfect. But, they do need to be free of serious defects that could (and do) result in early mortality.

Gaining Clarity

It’s hard to fix what you can’t see. Years ago, I would think, “If only I had a crystal ball to see the trees’ roots and determine if there is a problem that could be corrected.” I wondered:

Root Girdling
Ambusk scanning a small tree container with the 2700 MHz GPR. (Photo: TreesROI/Ambusk)
  • What if we could produce a 3D image of the tree root systems – like an X-ray CT scan?
  • What if we could isolate root complexities and identify problems throughout the root ball?
  • What if we could predict outcomes if planted as-is, or if corrected before planting?

With these goals in mind, we created an ongoing collaboration with the scientists at Geophysical Survey Systems Inc. (GSSI) who have non-destructive testing (NDT) ground penetrating radar (GPR) devices.

There is still a lot of work ahead but we hope to soon introduce a 3D GPR Tree-CT system empowered by AI/ML software that not only assesses the quality of nursery stock trees but informs users of results in terms that they can easily understand.

Ideally, the system will inspect and assess the quality of tree root systems above ground, before planting, in a way that is easy-to-use, meaningful, and cost effective. For nurseries, quality metric measurements can be performed in production that result in higher quality tree stock. Essentially, the system could serve a predictive model to increase the life span of nursery stock trees and help them reach their potential.

With this tool (called INSIGHT™) and our root quality grading metric, root problems deep inside the root ball will be located and identified, with suggestions for corrective action when possible. The brain of the system is our Root-Analysis Software. Based on the GPR data and driven by root system variables established in our “Tree Root Quality Classification Model,” INSIGHT translates the data into meaningful information for tree buyers.

Here are some of our strategic goals for the Nursery Tree Industry:

Root Girdling
A bare-rooted container-grown tree root structure. Notice how the roots continued to grow from when they imprinted the walls of smaller containers. (Photo: TreesROI/Ambusk)
  • Growers can use this tool throughout the production process to help them maximize resources, train staff, improve product quality, and comply with order requirements.
  • With our free app, a QR-coded tree tag reader will provide anyone with root quality information and suggest actions to correct serious root system problems, if correctable.
  • Buyers’ order specifications can include root-quality grading with compliance verified by the QR-coded tree tag.
  • Grounded in science and data, our peer-reviewed model will support compliance with order specifications and may inspire improved industry standards for tree root quality.
  • To foster ongoing education, we will establish a foundation with a percentage of our profits to inspire others to continue our work. While our starting point is to inspect trees above ground, our learning will soon be adapted (v2.0) to trees in situ to offer risk assessment, diagnostics, and prediction – always with an action plan.

The underpinning objective of our research and the mission at TreesROI™ is straightforward yet far-reaching: increase the quality, value, benefits, and lifespan of nursery stock trees, for them to grow to maturity in the urban landscape. Because urban trees should never be strangled by their own roots.

TreesROIAmbusk has been a leader in urban tree stewardship since 2006 through her volunteerism in Vermont. Upon retirement from GE Healthcare in 2011 and a 40-year career in Finance/Controllership IT, she was inspired to solve a global problem that causes early and unnecessary tree mortality. Ambusk started TreesROI in 2012, and hopes to soon introduce INSIGHT™, the product outcome of the company’s research and development. She presented her research this year at the 2023 Trees + Tech Summit hosted by PlanIT Geo and The Landscape Below Ground V conference, held at the Morton Arboretum in Lisle, IL.

Do you have a comment? Share your thoughts in the Comments section below, or send an e-mail to the Editor at cmenapace@groupc.com.


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