Not Your Average Trees

Environmental Design in Houston is responsible for moving the trees to the site.

While the still-being-constructed World Trade Towers signify closure and new beginnings for many, there were other signs of life around that area – trees. And the maintenance of those trees has been done by Bartlett Tree Experts.

The company became involved with the project in the summer of 2007, and since then has been responsible for every facet of care for the 500 trees. Wayne Dubin, Bartlett vice-president/division manager refers to the trees as "the world's most cared for trees" because of the high amount of attention they've received.

"We have a board certified master arborist who is out in the field monitoring these trees on average four days a week," Dubin says.

"We are sampling the water throughout the course of the season through the irrigation system, and we're sampling soil and custom blending fertilizer for each tree based on the origin of the tree from a nursery standpoint because they all have different soil profiles."

About 220 of the trees were planted in time for the ceremony commemorating the 10th anniversary of the Sept. 11 attacks. The company has been caring for the trees at the holding yard for four years, and the planted trees at the 9/11 plaza since August of last year. About 40 of the trees will be planted in Shanksville, Pa., where United Flight 93 crashed.

The trees are a single species, swamp white oak, which Dubin says was selected because "it's a tough tree and it doesn't have any meaningful insect or disease problems, and it was felt that it would be very adaptable to an urban environment." The only tree that will be on the plaza other than the oaks is the "Survivor Tree," a Bradford Pear that survived the Sept. 11 attacks, he says.

The company also installed moisture sensors in 25 percent of the trees' root balls in the holding yard, and those sensors reported back to a computer and monitored which root balls were becoming dry.

"Those sensors provide us with historical data in terms of soil temperature and soil moisture levels for all of the trees over the course of the four years they've been under our care at the holding yard," Dubin says.

Nearly 500 trees for the 9/11 Memorial were kept in New Jersey under Bartlett’s care.

Bartlett also has an online log that they're required to keep so that the owners and people close to the project can go on any time and look up the history of any particular tree in terms of its performance.

"The level of sophistication – we made sure that we did things that we wouldn't normally have done to ensure that the trees were getting the very finest care," he says.

"It's a great honor to be associated with a project where we can help people get some peace from a tragedy that for all of us as Americans was unspeakable and unimaginable," Dubin says.

The author is an associate editor with Lawn & Landscape. He can be reached at bhorn@gie.net.