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I imagine a sniper in the sky, picking them off, one by one. Ping! There goes a tree on Waubesa Street, chopped down without warning during construction. Boom! Down comes a maple on Talmadge, felled due to a neighbor's wish to build a new driveway. Bam! There goes an oak in Olin Park, victim of a fungal disease known as oak wilt.
This sniper has no organizing theory, no special gripe; its malice is mostly random. Residents may find one day that the tree shading their house is gone. The week before, it might have sported a spray-painted yellow dot, a common sign of condemnation. Or maybe not.
In the summer of 2008, Laura Townsend and Carol Stace returned to their home at 122 Waubesa St. following their shifts at the VA hospital, only to find a stump where a city-owned tree had stood. Several other, bigger trees nearby had also disappeared.
"We came around the corner and it was weird - all these trees were gone," recalls Townsend. "What happened?"
Last July, a similar scenario unfolded on Spaight Street, where five mature trees unexpectedly had to be removed after a contractor, S&L Underground & Trucking of Sauk City, mangled roots during street work.
One homeowner, local performer Truly Remarkably Loon, lost a 40-year-old, 25-inch-diameter basswood, the only tree shading his house from the southern sun.
"[S&L] came through and cut a straight line, and didn't consider the tree very much," says Loon. "It's tragic. In our lifetime, there will never be a tree that big there again."
If the streets had been in Milwaukee, those trees might still be standing. That's because Milwaukee long ago wrote specific language into street construction contracts to prevent trees from being damaged or cut, and to impose fines on violators. The loss of Loon's basswood, for example, could have led to a $5,000 penalty, taken directly from the contractor's paycheck. In Madison, contractors simply walk away (see sidebar, page 12).
As trees go, Loon's was not particularly glamorous or handsome. It was just one of thousands lining city streets and many thousands more shading backyards and parks.
Some are oak, some are honey locusts; many are ash, walnut and silver maple. Some, like box elder and Norway maple, are now considered weeds. But leaf for leaf, each provides value: shelter for wildlife, shade for our houses, calm repose for our scattered senses.
Road construction is only one of dozens of threats to the urban forest. The bullets come from all directions: Students who load the terrace with broken furniture, TVs and toaster ovens, compacting the soil and causing the imperceptibly slow decay of delicate feeder roots. Landscape companies that fail to water young trees, leaving them to crinkle in July's droughts. Bugs and diseases that crunch on bark and dissolve leaves. Lightning and storms that can topple trees one moment to the next.
In an older city, the toll on large old trees can be immense. Just this summer, besides the trees lost on Spaight, 14 trees were cut on Maple Avenue during construction, mostly because they interfered with power lines. And as part of the Monona Drive street-widening project that began in July, 175 trees will eventually come down, including many giant oaks. Twenty-five smaller trees will be moved to new sites, says project engineer Jim Foley.
In 2006, another tree controversy drew the attention of former east-side city alder Judy Olson, who remains concerned about long-term effects on the central city.
"When a tree comes down, the tree species that is planted is often times a much, much smaller maturing tree, even ornamental, not something that is going to shade our streets or provide cooling to the heat island we live in," says Olsen. "If we continue down this path, in 20 years we're going to have a very different-looking city."
The trees among us
As a discipline, urban forestry is a strange bedfellow with its cousin, rural forestry, which has economic issues at its core and isn't focused on single trees. Urban forestry fits more neatly with other urban programs such as storm-water control and neighborhood beautification and cooling.
As the "green" component of urban infrastructure, trees may fulfill a wider variety of needs than the "gray" components. Yet they are also often the least appreciated and the most fragile: A 50-foot-tall tree is, essentially, irreplaceable.
"Trees are just as important as a fireplug or a streetlight," says Marla Eddy, Madison city forester. "We don't have a chance to 'do it over' with trees."
For the last 20 years, Madison has been an officially designated "Tree City U.S.A." by the national Arbor Day Foundation. There are an estimated 300,000 city-owned trees within the city, with about 100,000 of those found on terraces, the strip of green between sidewalks and streets. In backyards and commercial byways, the number is much higher: In fact, estimates are that nine out of every 10 trees are privately owned.
Put all these trees together, and you have the concept of an urban canopy: the forest in which we live. Street trees may be the ones we see, but the other 90% are working hard for us too.
Researchers at the U.S. Forest Service have quantified that work in dollar terms: the amount of ozone they absorb, how much they reduce air-conditioning costs in summer, the amount of carbon they store, and the extent to which they slow down stormwater flows. And some U.S. cities have taken the trees-are-good mantra all the way to the federal Environmental Protection Agency, where efforts are under way to allow their air-cleansing qualities to be calculated into a city's air-pollution mitigation plan.
Further, the forest is an economic asset that grows in value as trees increase in number and size, adding property value to nearby homes, and measurable just as an insurer calculates the cost of rebuilding a house gutted by fire. The doomed basswood on Spaight Street was worth $4,415, according to city calculations.
While trees will never single-handedly solve our pollution and climate issues, they are an important part of the mix. But American Forests, a national advocacy group, warns that many city forests are declining due to increases in roads, parking lots and buildings. The group calls for a total city canopy cover of 40%, which most cities don't meet.
Minneapolis, which still boasts hundreds of large American elms thanks to aggressive action against Dutch elm disease, has a canopy cover of 26%. Trees there remove 384 tons of air pollution every year, valued at $1.9 million, and lower building energy costs by $216,000 each year, according to a Forest Service analysis. In Milwaukee, which has far fewer elms but lots of Norway maple and ash on streets, canopy cover is 21%.
Madison, says Eddy, has never undertaken a canopy analysis.
The environmental economics of urban trees, however, are predicated on maintaining and increasing the canopy, not only in terraces but in parks and backyards, too. When large trees are replaced by small trees, the asset clock is reset to zero. Add in the cost to plant and grow a new tree, and the equation suffers even more.
At the regional Forest Service office in Syracuse, N.Y., research forester David Nowak, who pioneered the urban forest studies, is confident in the science. He just wishes humans would play along.
"The benefits get larger as the trees get bigger, and long-lived is important," he says. "Dollar for dollar, if we replant every 10 years versus growing a 100-year-old tree, the costs eat at the economic benefits. So sustaining the canopy just makes sense."
New pest next door
The airy building housing the Madison forestry program, nestled just behind the Goodman Pool, is squeaky clean and deathly silent, except for a lone staffer on the telephone. On this day, a resident asks about overhanging branches.
"If I can get a name and address and phone number, we can have someone out to take a look at it," the staffer says.
As city forester, Eddy oversees a staff of 29. Last year the program fielded 4,500 requests for service, with 700 of those considered emergencies. Eddy says the daily press of calls about decay, broken limbs and possible disease is so great her staff does little more than react to problems, rather than anticipate and prevent them.
Yet she's proud of new practices she instituted after taking the helm four years ago. Back then, work orders were still written on paper and the city had only a rough idea what trees grew on its streets. Eddy began a computer-based tracking system and secured money for a street tree inventory, now in its third and final year.
The inventory pinpoints the location, species and health of every tree on every public street. The inventory is not as complete as a full canopy analysis such as Minneapolis' or Milwaukee's, however, as it covers only street trees.
Nonetheless, the inventory will be helpful when - that's the word she's been using instead of "if" - the pest known as emerald ash borer arrives here.
Deborah McCullough, a forest entomologist at Michigan State University and one of the nation's foremost experts on EAB, considers the invasive insect "the most destructive pest that's ever been in North America." The insect, which bores tunnels under bark, destroying a tree's ability to circulate nutrients, caused the death of every one of 7,100 street ash trees in Ann Arbor, Mich., with 30 million total dead ash statewide.
In 2005, officials estimated it would take 13 years before the emerald ash borer arrived in Wisconsin. But already the bug has leapfrogged through a handful of states and been found in a handful of Wisconsin counties - including Milwaukee County, less than 100 miles from Madison.
EAB is more dangerous than other pests and diseases, because by the time it's detected, it's nearly always too late to save the tree. And, until recently, the only strategies for combating it were quarantining nursery stock and firewood and eliminating ash in infested areas, all without effect.
But then a two-year, 175-tree study conducted by McCullough and others found that an insecticide injected directly into the tree's trunk either killed the borers or slowed them down.
The insecticide, emamectin benzoate, known by the trade name "Tree-äge," was developed by the Swiss agrochemical company Syngenta and Massachusetts firm Arborjet. While state entomologist Chris Williamson is urging caution, McCullough is more positive.
"By using Tree-äge, it gives you more time and more years to plan," McCullough says. "If you can keep trees alive through the tidal wave [of infestation], you'll have a better chance of keeping trees alive long-term with less insecticide.
"Look at the alternative," she continues. "If you don't treat your tree, then you're going to have a dead tree. And there's some negative side effects of that."
Indeed, the cost of removing infested trees and planting new ones is enormous. Ann Arbor, a city of 28 square miles and 114,000 citizens, ran short of money to do so; it's now hoping residents will plant new trees as a public service and claim a charitable donation.
So far in Wisconsin only Milwaukee - the city that pioneered construction protections for trees - has elected to use Tree-äge on its ash, hoping to slow or stop the insect's spread. (Another city, Cedarburg, is treating ash with a different insecticide.) It's an expensive solution - $600,000 was set aside in the 2009 budget to treat 32,000 ash trees - but removing and replacing all those ash would cost $27 million, according to forestry calculations.
"When [city leaders] saw the math, they saw that we could inject for many years and still never approach the $27 million figure," says Milwaukee head forester David Sivyer.
Except for state-mandated aerial spraying for gypsy moth, Madison has never treated trees for pests and diseases, Eddy says. How city leaders and residents will react to the emerald ash borer, she adds, is an open question.
Where's the spark?
St. Paul Avenue on a hot day is no picnic, but the heat is just right for tomatoes blushing red in dozens of community garden plots that line the road. Some years ago, in pursuit of more garden sun, a few well-established trees were cut along the bicycle path.
It's not the first time I've seen this tradeoff. In a different year, a friend cut down a 12-foot oak from her yard to gain more light. Today, new neighbors grow vegetables where that oak once stood.
Take a left onto Talmadge Street, however, and the temperature dips noticeably. Here, maples and ash arc high over much of the street, but it's clear that snipers have been visiting. Two giants that once stood at the street's entrance were removed and never replaced. Down farther, two more open spots, but these with saplings where their forebears once stood. Canopy, interrupted.
When Dutch elm disease first appeared in the 1960s, most communities, including Madison, didn't intervene, but watched elms die and then replaced them with ashes, maples and locusts. Other cities, such as Minneapolis, had fewer losses because they more aggressively identified diseased trees and removed them to prevent the fungus' spread.
In the end, the cities that highly value their trees are the ones that best protect them: cities like Milwaukee, Minneapolis and even the village of Shorewood Hills, which is now using a state urban forestry grant to control oak wilt in a small park. Milwaukee's spark came from a now-deceased forester, Bob Skiera, who impressed on city officials that there was a cost to act and a cost to doing nothing. So Milwaukee began to act.
Perhaps Madison's spark ignited last summer. The outcry over the loss of Spaight Street trees was by far the loudest protest that the forestry program has ever heard, says Marla Eddy. Asked why, she replied: "I would say the awareness [of trees]. Do other neighborhoods take trees for granted?
"Citizens ultimately are the bosses," she continues. "It takes all of us to be the Loraxes."