While efforts have been underway to clean up and rebuild in Iowa since the August derecho, one thing in particular will take years to replace — trees.
Greg Walston, Iowa State University Extension program director in Benton County and a member of the Benton County Disaster Relief Coalition, notes one of the biggest challenges after the derecho is meeting demand for trees, and determining what's salvageable and what isn't.
"For rural areas, the biggest thing is assessing all the damage. What does that look like, and where are the trees going to come from?" Walston says. "A lot of these older windbreaks took a pretty good hit. I would say some of the older windbreaks are probably anywhere from 50% to 75% damaged. The younger windbreaks aren't so bad. Windbreaks did what they are designed to do, but they took the brunt of the storm, and I think that's why not many houses were damaged by the derecho."
Mark Pingenot, Benton County Soil and Water Conservation District commissioner and a certified arborist, says the effects of the derecho will be long-lasting. While some trees died as a direct result of the derecho, some trees may start a process of decline and die within three to five years. In particular, he notes, oak wilt disease is likely going to become a problem in the coming years.
"At this stage in the game, it's beyond anyone's control," Pingenot says. "The red oak subfamily is more susceptible to succumb to the oak wilt fungus than species in the white oak subfamily. If you have to prune or trim storm-damaged oaks during the growing season, you want to make the cut and immediately seal the wound with a latex paint. So, by the end of August of last year, it was already too late to prevent oak wilt transmission."
However, before landowners get started with the replanting process, there are a few things to consider. Mark Vitosh, Iowa Department of Natural Resources district forester based in Johnson County, says the first thing landowners should do is evaluate what's left after the derecho.
"If there's nothing left, or the majority of trees received significant damage, often the best thing to do is clear what's there and completely start over," Vitosh says. "In some cases, there may be sections of the windbreak left. The challenge is you can't just replace an individual spot. If you lost a few trees, there aren't many shade-tolerant trees you can establish between bigger trees. Either you don't replace them, or you can put a new row to one side of the windbreak and start over."
When it comes to species selection, it's important to get assistance from your local soil and water conservation district or the Natural Resources Conservation Service to determine the best fit for your soils. However, as Vitosh notes, there aren't many options for evergreen trees well-suited to Iowa.
"Arborvitae does pretty well if you don't have a deer problem. Eastern red cedar is a good windbreak tree, but people don't like it because of its appearance," he says. "White pine is good. The larger white pines were often heavily damaged by the derecho, but we don't typically get 120- to 130-mile-per-hour winds. In the right conditions, it's still an option. Norway spruce and concolor fir are also options, depending on the soil type."
Landowners and growers may be tempted to plant blue spruce, which is widely available and visually appealing. However, Vitosh notes there are some major diseases threatening blue spruce populations in the Midwest — in particular, Rhizosphaera needle cast — so the tree is not recommended. In windbreaks, with trees closer together, the risk is even greater.
For those planting multiple rows, Vitosh recommends planting two different species to provide more resilience against disease and insect pests. The ideal species depends on the goals of the landowner.
"It doesn’t have to be all conifers. You have to have some evergreen component for good, all-season wind protection, but it's OK to mix it up," Vitosh explains. "It could be two rows of evergreens and one row of hardwoods. If you want to establish wildlife habitat, you can do one row of evergreen and two rows of shrubs for habitat."
Pingenot advises to not plant trees too close together in windbreaks. Space trees no closer than 25 feet for large, maturing trees and half that distance for smaller-sized trees and shrubs.
"We tend to design windbreaks like walls. But science says windbreaks function more like eddies in a stream. When air goes through a windbreak, it creates a zone of disturbed air," he explains. "Once that eddy of air is created, this tunnel of mixed air forces the oncoming winds to go up and over it, relieving the wind load on the structures and livestock we intend to protect. With widely spaced trees, no tighter than 25 feet on center, you are still getting windbreak effects with trees 6 feet tall."
Pingenot encourages growers to look for quality rootstock when shopping for trees.
"You're looking for fine fibrous root systems. You should pull the plant out of the pot before you buy it. You want the roots to hold that soil together in the shape of a pot, and you want the tips of the roots to just reach to the outside of the pot," he says. "There's a balance between not having enough roots to hold the soil together and having the roots too long and creating encircling roots."
ISU Extension publication, Windbreaks for Wildlife, offers some information on windbreak design and species considerations.
Before making any decisions on windbreak design or tree selection, get assistance from local experts. Local Natural Resources Conservation Service offices can offer guidance on designing windbreaks and cost-share opportunities for establishing windbreaks.
Since the storm, there have been a number of efforts to help replant trees in Benton and Linn counties. This includes private businesses in the Cedar Rapids area, Kirkwood Community College's Re-Tree Iowa program, Trees Forever, the Iowa Department of Natural Resources, the Linn County Tree Equity Program, the Coalition to Support Iowa's Farmers and other organizations.
However, with strong demand for trees even before the derecho, it will likely take several years to completely replant trees and windbreaks damaged by the storm.
"We're not going to be doing this for just one or two years," Vitosh says. "It's a multiyear effort."