Premium ContentMouse over Home then click on Premium Content for information.As waters begin to recede after four months of flooding, the Missouri River is leaving yet another reminder of its power.
In the flood plain of cottonwoods, sycamores and willows, normally flood-tolerant trees are dying.
No one says every tree in the 600-mile flood corridor from Yankton, S.D., to Glasgow, Mo., will die. But the duration of the flooding has created an environment for trees that may be catastrophic. Tree roots covered with water cannot breathe, and without oxygen, they suffocate. Even when the water is gone, trees will be standing in saturated soil for weeks, maybe months, adding to their instability.
The signs of destruction already are appearing. Some trees have toppled. Some are leaning, and will topple with a wisp of wind. Some are turning color early or showing stress in other ways, with leaves curling, ironically, as in a drought.
And some trees will live, depending on a lot of factors, such as how long roots were waterlogged, how quickly soil drains around the roots, the species of tree and the tree's overall health before the flood.
That's why asking what will survive four months of flooding "is the trillion-dollar question," said Jeff Iles, head of the horticulture department at Iowa State University in Ames.
"It's really a case-by-case situation, depending on the species, the strong having a better chance of survival than the weak. However, because of the duration, we'll see much death and destruction," he said.
In less severe floods, cottonwoods, sycamores, willows and other flood-plain species would do OK, Iles said.
"But this is such an unusual event. We're kind of in uncharted waters ... and we may not know until next year."
Horticulturist John Fech saw the signs of tree stress on a recent drive between Omaha and Kansas City.
"Trees on the east side of the highway are already starting to die," said Fech, who works for the University of Nebraska-Lincoln Extension for Douglas and Sarpy Counties.
Fech couldn't help but think about Omaha's tree loss in the 1997 snowstorm.
"It's going to be devastating," he predicted for this year.
Brook Bench, Omaha parks maintenance supervisor, said he sees logs going down the river every day, another sign that many trees already are flood casualties.
"Trees on the Iowa side of the river (across from downtown Omaha) are stressed, turning yellow and dying. During a windstorm, we lost two big cottonwoods at Freedom Park. They were in standing water," he said. When floodwaters recede and soil dries enough to allow inspections, "debris cleanup will be our first concern," Bench said.
"Our biggest thing is safety."
Other experts agree that caution and safety should be the top priority as flood damage to trees is assessed. In public parks and in residential neighborhoods — anywhere along the river where people live, work and play — trees will present unpredictable hazards because it will be impossible to gauge the stability of a tree's root system.
Losses will be most notable where the river has bulged and levees have failed — around South Sioux City, Neb.; Omaha and Council Bluffs; Nebraska City; Hamburg, Iowa; Brownville and Rulo, Neb.; St. Joseph, Mo.; and Atchison, Kan.
Forester Eric Berg said he hopes homeowners and community managers can resist the temptation to remove trees until the soil has a chance to dry out. It's extremely dangerous to remove a tree with an unstable, rotten root system, said Berg, community forestry program leader for the Nebraska Forest Service.
And heavy equipment tends to compact and compress spongy soil, making water slower to drain in the future.
Berg said fall workshops on tree removal will be geared to working with trees in flooded areas. He is working with Graham Herbst, a community forester for University of Nebraska-Lincoln Extension for Douglas and Sarpy Counties, to offer a tree workshop in late September or early October.
Trees that don't topple immediately may linger awhile, prematurely turning color and dropping leaves. If they get through winter, some may even leaf out in spring, Berg said.
That doesn't mean they're out of the woods, said Jack Phillips of Omaha, a registered consulting arborist.
"Yes, buds can open even if the roots are dead, but buds won't last long without a vascular system to feed them," he said.
Roland Barth of Bellevue can only imagine how trees are faring in the river bottom near the Wetlands Learning Center. The area, about two miles from the Fontenelle Forest Nature Center, has sycamores that seem to reach the sky. And this summer, the road to the area has been closed because of flooding.
Barth, who co-wrote plant guides to Fontenelle Forest and Neale Woods, has seen how those giant trees look when they go down. First the bark peels off, sometimes in a thunderous crash before the tree falls, then the tree goes down.
Cottonwoods and sycamores aren't as long-lived as the bur oak of the uplands forest, Barth said, but they provide a majestic presence for some 70 years or so, making their loss particularly tough.
Given the duration of this summer's flooding, Barth isn't optimistic.
"I think down in the flood plain, they're all going to die."
Contact the writer:
402-444-1059, rhonda.stansberry@owh.com
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