Cornell Urban Horticulture Institute Team Evaluates Condition of National Mall Elms

Cornell UHI team Barbara Neal, Bryan Denig, and Nina Bassuk assess the health of one of the iconic elms ringing the National Mall. Photo by Yoshiki Harada

In April 2018, the Cornell Urban Horticulture Institute team of Nina Bassuk, Bryan Denig, Yoshiki Harada, and Barbara Neal released an extensive report on the elms (including American elms) of the National Mall in Washington, D.C. The report details a study conducted at the request of the National Park Service to examine the current conditions of the trees and soils on the tree panels of the National Mall, and it includes a fascinating history of the landscape. Here are some highlights from the report.

The National Mall elm trees are an important planting in the monumental core, yet they face several challenges. The soils of the tree panels are very compacted, most likely due to the constant pedestrian use and the numerous large organized events that take place on the Mall. Unevenness in the size and distribution of the tree canopy has resulted from decades of mortality (often due to Dutch Elm Disease) and the planting of certain elm varieties with growth forms that are seen as incompatible with the planting as a whole.

From June 17–20, 2017, the research team conducted a tree inventory and collected soil data and samples for later analysis. In addition, in November 2017, ground penetrating radar done by Council member Gary Raffel was used to document root growth for seventeen of the trees. This report deals with the current tree and soil conditions, while management recommendations are in a separate report to be released in late 2018 or early 2019. 

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Nina Bassuk on Why the Fall Color is So “Meh” Thus Far

Cover photo for Sept Oct 2010Our own Nina Bassuk was interviewed for this Schenectady Daily Gazette article about the thus-far disappointing fall color in the Capital Region and throughout much of New York State. The article includes an arresting pair of pictures contrasting the fall color at this time in 2016 with the fall color now on the same mountainside in Cobleskill.

Bassuk says, “The two triggers that are important for fall colors are the shortening days and the cool nighttime temperatures. We haven’t had much of the cool nighttime temperatures. In fact, September was inordinately hot. It was also very dry. The drought in September caused some leaves to fall before they could change color, but I think it was the lack of cool nights,” she said. “In some places, you can look at some hills and it could be July.” Read more here.