By Michael E. Ruane
Washington Post Staff Writer
Saturday, January 16, 1999; Page B1

Mark Hopkins stood over the corpse of the towering loblolly pine that had snapped at mid-trunk yesterday morning and lay sprawled across his front lawn and out into Utah street in northwest Washington.

He joked that his place used to be called "three pines," for the three giant loblollys out front. Now it was two and a half. All around him, glistening missiles of ice plummeted from frozen limbs, and a second pine tottered precariously over his home.

There was a brutal war of physics yesterday, as the overnight storm loaded tons of ice on the limbs and trunks of trees across the Washington area, bending the strong and breaking the weak under the weight of frozen water.

It was at times a beautiful struggle, with branches, buds and even grass coated as if in exotic glass; trees and shrubs almost everywhere jeweled and bowed; and the woodlands frosted in white.

And as the sun came out, it brought cascades of melting water from the coated branches, and a barrage of falling ice shards that pelted cars and shattered in the streets.

But in the end, the weather won out, snapping trees like brittle bones, hauling down countless utility wires in the process and causing one of the most extensive losses of electrical power in memory.

In many ways the fight wasn't fair.

Ice can build up tremendous weight on tree limbs and power lines – as much as 20 pounds a foot, experts said yesterday. And many urban trees aren't robust enough to stand up to that. A half-inch coating of ice on the average six-foot tree branch, for example, can rapidly produce an extra 120 pounds of weight, Wilfrid Nixon, an ice expert and professor of civil and environmental engineering at the University of Iowa, said yesterday.

"A six-foot tree branch is not terribly thick at the base," he said in a telephone interview. "I certainly wouldn't sit on one. You can very easily build up a lot of weight on a tree.

"Same thing goes for a power line," he said. "If you have a 100-foot power line, you might have 2,000 pounds of ice, a ton of ice. It surprises you. You tend not to think of it in those terms."

In addition, many urban trees do not withstand ice well. Generally, said Jeffrey O. Dawson, professor of tree physiology at the University of Illinois at Urbana-Champaign, city trees are less able to withstand ice storms than forest trees because a city tree has a fuller, ice-catching crown.

In the crowded forest, many trees do not develop large crowns, as do urban trees, which are grown and flourish in more open areas, Dawson said. The fuller the crown, the more ice is collected; the more ice, the more weight.

"Even though forest trees can be damaged" in an ice storm, he said, "the damage tends to be worse with open-grown, urban trees."

Furthermore, certain trees are just stronger or better constructed than others. Take Hopkins's loblolly pines. They are tall, slim, branchless trees with large, fat crowns at the top – not the type to withstand ice weight, Dawson said.

Trees with weak branch joints, shallow roots, or decay can also be susceptible, he said. But, mostly, it is the fuller trees with lots of branches to catch ice that are in danger.

"Generally the problem starts when ice loads on a branch system, and failure is more determined by the weakness of the branch juncture than by the strength of the wood," he said.

The pin oak is one tree that ice threatens. "It has a greater total branch area than other oaks," Dawson said, "therefore it accumulates greater amounts of ice, and that weight stress is transmitted to junctures of other branches, and it causes failure."

The Bradford pear tree is another likely victim, Dawson said. "The common Bradford pear has weak branch junctures. . . . These probably will have failed massively in the Washington, D.C., area."

Some trees, though, have adopted well to ice and snow. Dawson said the Kentucky coffee tree, a hearty Midwesterner with fat branches, is quite rugged. Illinois' supple bald cypresses bent under the weight of a 1990 storm but then sprang back later.

And mountain firs and spruces, with their short branches and conical shapes, are famed for their ability to shed snow and ice like a person wearing a coat, he said. "It's natural selection" for trees.

Much of this was lost, however, on the tens of thousands of haggard homeowners who had to deal with timber in the yard, wires in the street and the chill in the furnace.

As Hopkins, 67, stood over his stricken tree, along with his neighbor, "woodsman" Lincoln Furber, 67, who had brought a chain saw, he recounted the basics:

"My neighbor called me and said, 'Did you see the tree in your front yard?' I said, 'No, I haven't.' I looked out the window, and there it was. . . . It missed the car across the street – and a law suit – by about three feet."

"God's will," he chuckled.

"I came out and looked at it," he said. "The neighbors stood around. We all looked at the tree for a while. Then I got a camera, because you have to take a picture. Then I called the city."

"Then a guy from public works . . . stopped and said, 'I'll phone it in, and we'll clear the street, and the rest of it is your responsibility.' "