River Valley OHV Area, IA

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Jess Riddle
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River Valley OHV Area, IA

Post by Jess Riddle » Sun Nov 03, 2013 7:20 pm

NTS,

The River Valley OHV area is tucked between Omaha, NE and Council Bluffs, IA in the Missouri River Floodplain. ATV trails crisscross through two broad strips of forest separated by a mostly filled-in backwater. The strip of forest farther away from the river is over 60 years old and dark from a dense white mulberry midstory. Above them tower large cottonwoods, up to around 120’ according to LiDAR, and silver maples and sycamores are widely scattered. The younger forest is lower and more open. The mix of species is similar though mulberry is restricted to a narrow band near the river and silver maple is more common. Sand, often over three feet deep, covers the forest floor near the river while reed canary grass outcompetes all herbs except Japanese hops adjacent to the open backwater area. In between those stands the backwater area grades into an open area dominated by dirt bikes then a willow forest. In order of decreasing abundance, peachleaf, sandbar, and black willow form the open forest over dense reed canary grass.

During repeated visits to the site fork work, the willows stood out as exceptional. One peachleaf willow along the edge of the older stand stood out as the largest diameter I saw all summer. Sandbar willow is typically a shrubby clonal species, but tree sized individuals were common in the mixed willow forest. When I was visiting the Omaha area, I made measuring those sandbar willows a priority, because NTS has no data on the species. Unfortunately, that did not leave time for measuring the cottonwood saplings. After less than two full growing seasons, the largest samplings were around 14’ tall.
Cottonwood seedlings that germinated in 2012 photographed early August 2013
Cottonwood seedlings that germinated in 2012 photographed early August 2013
RiverValleyOHVmeasurements.JPG
Most of the larger sandbar willows are in decline. They seem to have reached their age/size limit. The largest sandbar willow grows in an open area at the end of the backwater surrounded by nothing but Japanese hops vines.
15'1" x 108.8' cottonwood
15'1" x 108.8' cottonwood
The tallest sandbar willow, 17" x 47.3'
The tallest sandbar willow, 17" x 47.3'
The tallest sandbar willow with a live top, 17" x 46.2'
The tallest sandbar willow with a live top, 17" x 46.2'
The largest diameter sandbar willow, 28" circumference below the upper fork
The largest diameter sandbar willow, 28" circumference below the upper fork
Jess

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