ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, June 9, 1996 TAG: 9606100036
SECTION: NATIONAL/INTERNATIONAL PAGE: A-6 EDITION: METRO
DATELINE: NEW YORK
SOURCE: The New York Times
ONE OF THE HARDIEST of trees to survive the grueling elements of New York City is now dead or dying, and no one can explain why.
Throughout New York City, in the public parks as well as in the grittiest neighborhoods, where it is often the sole provider of natural shade in a landscape of asphalt and crumbling brick, the tree of heaven is dead or dying.
The New York State Department of Environmental Conservation is carrying out an emergency study to determine what is killing the Ailanthus altissima, a tree so hardy and opportunistic that many see it as a scourge.
It sprouts happily in sidewalk cracks, can grow 20 feet in a few seasons and is the central symbol of big-city survival in the novel ``A Tree Grows in Brooklyn.''
``No matter where its seed fell,'' the novel's author, Betty Smith, writes, ``it made a tree which struggled to reach the sky. It grew in boarded-up lots and out of neglected rubbish heaps and it was the only tree that grew out of cement.
``It grew lushly, but only in the tenements districts.''
In fact, the tree of heaven was never so choosy, and it established itself tenaciously throughout the city shortly after being introduced in Central Park by Frederick Law Olmsted in the late 1850s.
And now, throughout the city, it is in trouble.
``Whole stands are dying,'' said Michael Birmingham, an entomologist with the conservation agency in Albany. ``The tree is so abundant on vacant lots and disturbed sites. For some folks, it's the only shade. If it dies, they don't have a tree.''
No one knows exactly why. The deaths are not being blamed on last winter's heavy use of road salt, which is threatening many of the city's trees, since the problem emerged before that. The state has identified three fungi that may be to blame. And the factors of compacted urban soil and drought are also being considered.
Similar single-species epidemics have affected flowering dogwood, butternut, shagbark hickory and hemlock trees across the nation in the last few years, but the ailanthus problem is known only in New York City.
In normal conditions, the tree of heaven is so hardy that, a few years ago, the city Department of Transportation started treating stumps in highway medians with herbicide; otherwise, the tree regenerates quickly from its ropy yellow roots and its branches obstruct drivers' lines of vision.
It is not usually a problem in forested areas, where competition with other plants keeps it in check.
The ailanthus has been part of the northeastern landscape for two centuries. A native of China, it was exported to England from China in the 1750's, and introduced to the United States in 1784. Charmed by its tropical appearance, Olmsted used it in his design for Central Park. The tree proved amazingly vital, jumping the park's borders and spreading across the city.
Growing to 90 feet, the tree is a late bloomer in spring. Its smooth leaves reach three feet in length and contain as many as 41 leaflets. Yellowish green in spring, the leaves turn dark green by summer. Blossoms usually occur about now, but instead, the trees are dead or failing.
The tree's overall health has not been good for a decade. In recent springs, a wilt disease was blamed for withered shoots found on mature trees as well as saplings.
``The saplings start from roots of the mature trees,'' said Tony Emmerich, project manager for the urban forest and education program of the City Parks Foundation. ``The bark starts peeling. Under the bark of dead trees, there's shoestring fungus, and invading insects tunnel there.''
Like other tree experts, he said the toll would only increase. ``Wait till this summer when more trees die,'' he said. ``Then you'll really see people getting upset.''
Even if the state can identify the killer, there seems to be no interest in protecting the ailanthus. A replanting program has already begun, with several hundred trees planted, all chosen from native species. Imports like ailanthus often flourish at the expense of other plants.
``We're working in woodland situations where ailanthus dies out, and we take advantage of this to reforest with something preferred,'' said Emmerich. ``I first heard about it in 1984, and I've been profiting from it since. I'm not concerned about the victim, unless it's planted along streets.'''
On Staten Island, the dead ailanthus is being replaced with several species of oak; on Hunter Island, in Pelham Bay Park, the replacement is white pine.
``Wherever I see stands of tree of heaven, I see mortality,'' said Birmingham. ``It's very conspicuous. In most of a stand of large trees, the dead seems to radiate out from a center, with ones furthest from the center least affected.''
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