Davey Tree : Ecological Services : Project Profiles : Howland, Ohio: ODOT State Route 11 and King-Graves Road


Howland, Ohio: ODOT State Route 11 and King-Graves Road – Wetlands Mitigation Area

The Project
When Ohio Department of Transportation (ODOT) constructed the interchange between State Route 11 and King-Graves Road in Trumbull County, wetlands were unavoidably impacted and restorative mitigation was required. A wetland restoration site was chosen and the mitigation wetlands were constructed.

Approximately halfway through the five-year monitoring period, it was determined that the mitigation wetlands would not meet their performance standards unless immediate measures were taken to reduce the invasive plant cover within the wetlands and to improve their overall native plant diversity.

Davey Resource Group, working with MS Consultants, devised and implemented a plan to restore ecological integrity to the mitigation wetlands.

The Plan
The plan unfolded in two critical steps:

Eliminating Lythrum salicaria (purple loosestrife), all Typha spp. (cattail species), and other invasive plant species within a two-acre mitigation wetland.
Re-vegetating the wetlands with native plants that would not only provide the required diversity, but would also prevent the re-infestation of invasive plants in the wetlands.

In October 2004, all invasive plants were treated with Rodeo® (a broad-spectrum glyphosate herbicide) using a high-volume, high-pressure spray apparatus. In March 2005, the remaining standing cattail litter was cut at ground level with a walk-behind sickle mower and the debris left in place to prevent future cattail seed germination. Two small spot-treatments for purple loosestrife and one for the small patch of cattails seen at right occurred in Summer 2005; the cattails did not return.

The wetlands were heavily planted in Spring 2005, to prevent a re-infestation. Davey cast a native seed mix across the elevated mudflats and installed hundreds of small shrubs and emergent plant plugs within the wetlands. In addition, eighteen 2- to 3-inch caliper trees were installed to provide immediate shade and a quick seed source for new trees. The invasive plant species Davey eradicated are shade-intolerant; the addition of these larger trees will reduce and eventually eliminate the need for chemical control.