Return of the American elm: a beloved classic, long missing from city streets, is starting to make a comeback.
Their tree of choice: the Princeton American elm. The National Park Service's suggestion probably surprised many of those who've mourned the loss of as many as 100 million American elms to Dutch elm disease over the last 75 years. But "nothing is comparable to the American elm" for its adaptability, hardiness, form, and connection to American history, says Jim Sherald, director of NPS's Center for Urban Ecology.
Scientific confirmation of resistance to Dutch elm disease among some pure American elms gave the Park Service several to choose from, and the Princeton's tall, arching, and fast-growing form made it the logical choice. It also helped that a nursery, Riveredge Farms outside Atlanta, Georgia, had been growing these particular trees long enough that the Park Service could quickly obtain a shipment of 88 5-year-old trees.
Since their planting in the spring of 2005, the trees have grown about an inch in diameter and many are more than 20 feet high. Some in single and some in double rows on either side of the avenue, they are already starting to arch overhead in the cathedral-like way that so distinguishes the American elm and made it the most beloved street tree ever in American towns and cities.
With Dutch elm disease (DED) continuing to fell tens of thousands of trees each year, how did the American elm become a safe enough tree to plant in such a prominent place? And what does that signal for other urban forest projects and, ultimately, for consumers?
AN 'ENVIRONMENTAL CATASTROPHE'
In his award-winning book The Republic of Shade, historian Thomas J. Campanella traces America's captivation with elms back to New England's Village Improvement Societies, which in the mid-1800s transplanted elms by the thousands from the woods to the towns in what he calls the first environmental movement in this country.
Because elms were native to almost every region in America east of the Rockies, so easily transplanted, and so fast-growing, they quickly improved the appearance of communities. This led them to be planted almost exclusively in many rapidly growing cities and towns. Not by the tens of thousands, but by the hundreds of thousands.
But this hardy tree's attributes led to its establishment as a monoculture in many urban areas, and that, ultimately, contributed to its downfall.
Dutch elm disease arrived in Cleveland on a shipment of bark beetle-infested logs in 1930. Fungal spores carried on the beetles' backs and legs spread the disease rapidly throughout the East Coast. It marched into New England where its spread was greatly abetted by a freak hurricane that ripped through the region in 1938, nearly denuding quaint hamlets and cities and leaving behind dead and damaged trees for the bark beetles to thrive on.
AMERICAN FORESTS (then known as the American Forestry Association) led a coalition to obtain federal emergency funds to battle the disease during its early years. But little helped, and for three-quarters of a century now, cities have been desperately trying to save their elms and contain the disease. Campanella calls the loss of American elms "an environmental catastrophe really unparalleled in American history."
PASSION STIRS ACTION
All across the country the loss of elms still feels personal. "I am sad to say, now anyway, that the trees at that time were great," recalls Hubert Guest, a retired city manager who grew up in the small town of Coffeyville, Kansas.
"You could look down the street in the summertime, and you had these great elms that just kind of formed a tunnel of shade." he says. "You could go eight or nine blocks and these big elms made you feel like you were inside when you were walking down the street."
Minneapolis resident Norman Anderson remembers that, when he bought his house, "This block was solid elms with a beautiful arched canopy over the street, and it was a real disappointment to us when just where our block started, all the trees were gone. It looked like a new housing development with old houses. It was a very odd, odd thing."
Mary Hammond, a resident of one of Washington, DC's often-neglected neighborhoods east of the Anacostia River, says her street "was known because of its beautiful elms that towered over the avenue and formed this canopy. We began to lose all of them to DED, and this distressed me to no end."
Like many others, Hammond took action when confronted with DED's devastating impact. She formed a tree committee within her civic association, got connected to larger groups of activists, "and we then worked to get a tree bill passed in the city. That's our real big accomplishment, actually."
In Minneapolis, attorney Don Willeke and Rolf Svendsen, then a member of the Minneapolis Park & Recreation Board, cofounded the nonprofit Tree Trust in 1976 to help reforest the Twin Cities area in the wake of the disease. Together they rallied other residents, the business community, the state, and the Minneapolis Park Board to create a comprehensive elm sanitation and urban forest restoration program. Typically, the city removes and replants about 5,000 trees, often replacing elms with other trees that will grow large and have full canopies.
Residents--like Lori Mittag--appreciate the effort. Her street has "this nice cathedral effect. It is beautiful.... I can't imagine a city without its trees." The elms are so important to her neighbors that they raise as much as $15,000 every three years to inject fungicides into the trees to prevent the disease. When the occasional tree dies, the city is able to replace it with an elm.
Some cities and towns deal with Dutch elm disease through sanitation programs like Minneapolis's, considered the best method of containing the disease. Another strategy for protecting individual trees is to inoculate them with fungicides, as is being done with considerable success to large "heritage trees" in western Connecticut and Massachusetts by Elm Watch, a nonprofit founded in 1999 by photographer Tom Zetterstrom.
Still, Dutch elm disease is very much alive and well. Minneapolis in 2004 had an especially bad year, when the city lost 10,000 elms.
"I come home and it's the first topic of conversation, that there's more orange rings [which signify which trees need to be cut] around these big, beautiful, wonderful trees," Mittag says.
TAPPING INNER STRENGTH
Despite Dutch elm disease, the American elm deserves a comeback, says Jim Sherald of the Park Service. "It's a tough tree," he says. "If you can avoid the Achilles heel of Dutch elm disease, it is still a tree worthy of consideration in urban settings."
Avoiding the Achilles heel is just what some scientists were determined to do. They started by noticing elms that remained healthy even as neighboring elms got the disease and died. "Such trees survive most likely because they possess a kind of natural immunity to the disease," wrote Campanella.
For decades, researchers have puzzled over this phenomenon. Some focused on breeding American elms with DED-resistant Asian and European elms, which resulted in several cultivars with varying levels of resistance to the disease.
"The results were the first hybrid elms to gain significant street tree use in the U.S. as American elm replacements," says Keith Warren, director of new product development for J. Frank Schmidt & Son Co. of Boring, Oregon, a company that grows trees for nurseries and landscapers across the county.
Most significant, however, has been the work of Alden "Denny" Townsend, who recently retired from the U.S. National Arboretum. Townsend's extensive research identified pure American elms that do in fact have a substantial tolerance for Dutch elm disease. This means that even if the tree becomes infected and shows symptoms, it can recover without long-term damage.
Much of today's renewed interest in American elms followed from Townsend's 1995 release of the Valley Forge and the New Harmony elms to the nursery industry. A subsequent large-scale evaluation of disease tolerance found that the older cultivar, the Princeton American elm--a 1922 selection of William Flemer Jr., owner of Princeton Nurseries in New Jersey--has a high level of disease tolerance, especially good news for a tree originally grown for its outstanding horticultural characteristics. A 75-year-old stand of these elms continues to thrive on Washington Road in Princeton.
The National Park Service also found a significant disease-resistant American elm right outside the Smithsonian Castle on the National Mall, which has 600 elms along its nearly mile-long expanse. Named the Jefferson elm, it was released to the nursery industry in 2005. Other cultivars of American elms that show promise include the Prairie Expedition, selected by North Dakota State University, and the St. Croix, about to be tested by the University of Minnesota.
PRINCETON CATCHES ON
But it is the Princeton American elm that has the greatest potential for success as a large tree attractive to garden-center customers, corporate and city landscapers, and others. It is less floppy or gangly than its disease-tolerant cousins in its first years, "the nicest looking" as a young tree, according to Warren and others.
Given the history and performance of American elms in Washington, DC, the nonprofit Casey Trees wanted to include American elms in its effort to help regreen the city. Casey Trees was founded in 2001 after a Washington Post article about AMERICAN FORESTS' satellite analysis of DC's land cover caught the eye of philanthropist Betty Brown Casey. The article showed a sharp decline in tree cover from 1973 to 1997, the period also with the most elm loss in the District. This moved Casey to contribute $50 million as the endowment for a new organization and to ask that the new organization make a special effort to include elms in its plans.
To obtain enough elms for its plantings, Casey Trees contracted with nurseryman Roger Holloway of Riveredge Farms to grow disease-resistant Princeton American elms. In four years Casey Trees volunteers planted 750 Princeton and 80 New Harmony elms. This helped stabilize the continuing loss of elms in the city; there are currently about 8,500 elms lining the streets of Washington.
While still young, the elms planted by Casey Trees are doing very well. According to executive director Mark Buscaino, "We have new data on trees that we've planted, and we're finding that of the 30 or 40 species we've planted, elms have the highest survival rate. They establish themselves quite quickly, you don't have to keep going back to them for maintenance, and they can be planted practically any time of the year."
Because of the interest by Casey Trees and others, Riveredge Farms has gone into Princeton elm production in a big way, which is why Holloway had sizable numbers to offer when the National Park Service sought them for planting in front of the White House.
Equally significant, the availability and desirability of the Princeton elm has led to the first large-scale roll-out of this classic tree across a large portion of the U.S. This spring, The Home Depot will make available 12,000 trees in select stores in the Midwest, Northeast, Mid-Atlantic, and part of the Mid-South regions, according to Dan Stuppiello, the retailer's live goods merchant, northeast. By 2009, Home Depot expects this number to increase and be sold in its garden centers "in all states that are suitable to elms," he says.
By making the Princeton elm available directly to consumers, "We believe we have the opportunity to replace a lost piece of American history," Stuppiello says.
"This is far and away the biggest retail availability of disease-resistant American elms," nurseryman Holloway said.
In addition to this commercial roll-out, Alice Ewen Walker, executive director of the national Alliance for Community Trees, also sees a large role for hundreds of other tree-planting groups throughout the country that can be encouraged to plant elms. She believes her members see disease-resistant elms as offering "a great opportunity to add to the diversity of trees planted nationwide through our Neighbor Woods program--and elms are a great conversation starter for community outreach in neighborhoods. People really respond to them."
One resident certainly does. Dennis Chestnut is chairman of the Watts Branch Community Alliance, a grassroots organization restoring a streamside community park in one of Washington, DC's more neglected northeast neighborhoods. Trained by Casey Trees as a citizen forester, Chestnut has been replanting American elms like the ones he recalls cooling and shading his neighborhood prior to the Dutch elm disease epidemic.
"In a city where there are high levels of stress, hypertension, and asthma, streets and parks with these great elm trees will provide an outlet for citizens to be able to come relax, take their stress levels down," he said."
As in Chestnut's neighborhood, the American elm should be coming soon to a street near you.
Catherine A. Smith, president of Community-Based Communications, LLC, of Cheverly, Maryland, recorded some interviews for this article while making the documentary The American Elm: Magnificent, Imperiled, Renewed.
Photos by Dan Smith.
RELATED ARTICLE: NATIONAL TRIAL JUDGES ELMS' CHANCES
Rapid growth and eventual height and canopy size are among elms' desirable features as an urban tree when it comes to ecological benefits including carbon sequestration. "The mature size of the tree is very important," says Greg McPherson, director, U.S. Forest Service Center for Urban Forest Research. "A common reaction is to say that very fast-growing trees (like pears) sequester more carbon dioxide, but over the long term, what's desirable is stable carbon reduction. I like to see trees as long-term investments.
"Long-lived, large-growing trees like American elms (and others with a crown of 50 feet or more, such as oaks, plane trees, maples, etc.) will be the best investment over 50 years for the dollars spent for planting and care," he says.
"As these trees get older and larger, the rate of sequestration slows, but they continue to reduce heat islands, reduce winter wind speeds, and offer other benefits. The reduction in sequestration is offset by reduced energy use" through conservation and careful placement of trees, McPherson adds.
McPherson and his colleagues at the University of California, Davis, are one of 16 teams of researchers, agricultural Extension specialists, and commercial nurseries participating in the National Elm Trial to evaluate the use of Dutch elm disease-resistant American and hybrid elms.
The national trial of commercially available elm cultivars currently includes evaluation sites in 15 states; they will be evaluated over a wide range of growing conditions and hardiness zones. This nationwide study has one coordinating and reporting system that is based at Colorado State University, which will report performance data for trees at all sites (see http://treehealth.agsci.colostate.edu/index.html).
"The trial will help to pinpoint the positives and negatives of cultivars in various parts of the country," McPherson says. Its other objectives are to determine the relative disease, insect, and stress tolerance of these cultivars, and to promote the cultivation and use of elms by wholesale tree propagators and growers, retail nursery and garden center operators, landscaper designers, arborists, and the general public.
In addition to the work of scientists and the nursery industry to identify and bring additional disease-tolerant trees to urban landscapes, another project is attempting to restore the American elm to forested landscapes. Directed by Jim Slavicek at the U.S. Forest Service's laboratory in Delaware, Ohio, this project is working to establish DED-tolerant trees in the wild where their resistance characteristics will evolve to combat an ever-mutating Dutch elm disease fungus. If successful, the project will provide future disease-tolerant trees for use in urban settings, as well as ensure the retention of American elms in forested settings.--Catherine Smith
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|Author:||Smith, Catherine A.|
|Date:||Mar 22, 2007|
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