When people think of the Martin Luther King, Jr. Memorial, they usually picture the larger-than-life statue of Dr. King. But beyond the statue itself, the surrounding trees are a key contributor to the memorial’s majesty.
This month, the memorial, which opened in 2011, will receive the Canopy Design Award from Casey Trees, a non-profit that focuses on building up DC’s tree canopy.
Yoshino cherries and American elms frame the MLK Memorial
The monument site, a four-acre plot on the northeast corner of the Tidal Basin, is near both the Jefferson Memorial and DC’s famous Yoshino cherry trees. A gift to the US from Japan in 1912, the cherry trees draw hundreds of thousands each spring for the National Cherry Blossom Festival.
In designing the MLK Memorial, Oehme van Sweden (OvS), the landscape architect for the project, added 182 new cherry trees to the site. The setting strikes a reverent balance between the beloved legacy the memorial represents and the other history that’s in the surrounding area.
Adjacent to the cherry trees, OvS designed a garden plaza with curving paths. It encourages visitors to walk around and take in both the massive sculpture of Dr. King as well as the surrounding planters full of cherry trees.
OvS also added nine new American elm trees at the memorial’s entrance along West Basin Drive. The tall, healthy trees create a welcoming entryway for visitors. As they mature, they’ll create an arched canopy, subtly guiding people to the memorial area and creating an element of serenity.
The shade from the elms also makes the entryway cooler in the summer and blocks the wind in the winter. The trees also serve as a buffer from traffic.
Once one of the most popular street trees in the country, American elms are hardy trees known for their beautiful vase shape. Huge numbers of American elms have been destroyed by Dutch Elm Disease over the last 30 years, but new breeds can tolerate and even resist the disease.
The memorial’s trees and soil also serve a functional purpose
Landscaping at the MLK Memorial reflects the cutting edge of green infrastructure, using trees, plants, and soils to provide “eco services” like shade and water treatment.
Beyond nurturing the trees, the soil helps prevent flooding and pollution on the site. For example, rain on paved surfaces like sidewalks and roads flows into the soil, absorbing and cleaning it rather than sending it into the Tidal Basin or sewer.
To keep soil for the trees along the sidewalk and in the plaza from compacting, which prevents roots from accessing water and air, OvS used a structural support called Silva Cells (which my company supplied). Silva Cells keep soil from getting too dense, which makes it easier for trees to get nutrients.
While this project was designed prior to the Environmental Protection Agency’s Clean Rivers, Green District program, OvS’s green infrastructure design approach aligns with the program’s goal to “achieve sustainable stormwater management, more livable communities, and other environmental improvements in the District.”
For example, the design accounts for periodic flooding from the Potomac River. When Hurricane Irene caused the memorial to flood in 2011, all of the plants survived.
The memorial’s trees and plants compliment the sculpture’s powerful reminder of the man it honors by creating a serine environment. They usher visitors into the memorial space and provide a visual callback to the history of the capital and the nation. The tree canopy shelters and anchors people, creating a personal, contemplative experience. The thoughtful landscape design ensures that the trees and other plants endure and thrive, a fitting echo to the permanence of Dr. King’s legacy.
The Design Award will be presented at Casey Trees’ Canopy Awards on Thursday, April 23, 2015.