Nature's Notes: Wildlife can flee floods; trees can't

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Like many people, deer, cottontails, brown snakes and other wild animals evacuated as flood water rose. As the water descended they returned home.

Trees aren’t as fortunate as wildlife. They can’t move and must either survive high water or die.

Fortunately, many tree species are perfectly adapted to the heavy compacted soil of floodplains and normally survive high water unscathed. Particularly well adapted trees include silver maple, cottonwood, box elder, green ash, mulberry, sycamore, willow, and pin and swamp white oak. In contrast, white oaks, sugar maples, and most conifers live high up on slopes and are almost never found on floodplains where flooding is toxic to them. Other trees, including elms, bur oak, and walnut, are somewhat flood resistant.

Whether a tree survives flooding depends on its species, the time of year, the water level, and the length of inundation. If inundation is brief, as it was during the 2008 and 2016 floods, most trees recover completely. In 1993 inundation lasted for weeks and flood sensitive species died. Even flood tolerant trees often die if their foliage is inundated for more than a short period. Tree species adapted to living in floodplains often are the most successful species in urban and suburban areas. River water compacts soil in the floodplain, and human activity does the same thing in town. Species that like tight soil do well in both places.

There is an interesting aspect of tree adaptability. White oaks and other strictly upland species are hardly ever found in places that flood. In contrast, flood adapted trees usually do well in uplands, so it’s not unusual to find a cottonwood or silver maple on hills.

Marion Patterson is an instructor at Kirkwood Community College. Rich Patterson is the former executive director of Indian Creek Nature Center in Cedar Rapids.

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