Iowa takes an ax to ash trees

By Perry Beeman and Jason Pulliam
Des Moines, IA (January 6, 2011)- Iowa cities and park managers have started the long, costly process of ridding Iowa of ash trees threatened by a seemingly unstoppable pest.


In some cases, they are cutting down healthy ash trees, perhaps years before the emerald ash borer spreads across Iowa from Allamakee County, in far northeast Iowa. The tree-eating beetles were found there last year, on a Mississippi River island. Crews are focusing mostly on young, damaged and ill trees, using the latest threat as a reason to get a hardier mix of trees along city streets and in parks.
Ash trees already have met chain saws in Des Moines, at Iowa State University in Ames and at Saylorville Lake campgrounds in recent weeks. Cedar Rapids is getting ready. At an average cost of $1,500 per tree for removal, cities and park managers face a huge tab. Costs for removing ash trees could climb to $15 million in Des Moines alone.
Starting removals now is part of a strategy to spread costs over time while increasing forest diversity, said state entomologist Robin Pruisner of the Iowa Department of Agriculture and Land Stewardship. “It’s all about eating the elephant one bite at a time,” Pruisner said. “Cities need to do an inventory of ash trees first. If they have a lot of ash trees, it might be best” to remove some now.
By starting the process early, “the new species will get some size, both for shade and aesthetics, instead of having a city where all the trees are gone,” Pruisner said. Getting a jump on removals also will help avert the possibility that large numbers of diseased trees will pose public safety issues and overwhelm workers, said Emma Bruemmer, urban forestry coordinator for the Iowa Department of Natural Resources. Staggering the growth of replacement trees also is intended to help avoid a hole-in-the-smile look like the 1960s Dutch elm disease outbreak caused.
Back then, public works crews often planted the fast-growing, shade-producing ashes to replace elms. In the average Iowa town, 12 percent of the trees along roads are ashes. The Department of Natural Resources has inventoried ash trees in more than 60 small towns, in part with a federal grant. The percentage of ash trees along streets can range from zero to 60, Bruemmer said. More inventories are planned.
Pruisner said it is highly likely all ash trees in Iowa will die at the hands of the beetle, which burrows under the bark and cuts off a tree’s food supply. “As of right now, there is nothing on the horizon that shows any promise of stopping or drastically slowing down the emerald ash borer,” Pruisner said. Much of Iowa’s forest includes ash trees, which also are common in city parks. The state estimated there are 52 million ash trees in Iowa’s 3 million acres of forest, and 88 million altogether.
The expected loss of ash trees represents a huge economic loss to the state. The trees will have to be removed and replaced, and their shade and value for wood will be lost. Some will be lost altogether for wood, or the wood will have to be treated before a sawmill can sell it.
The loss of an estimated 3.1 million urban ash trees in Iowa could cost cities $7.3 billion for removal, replacement and lost landscape value, the natural resources department said. The state economy also would lose $330 million because of the loss of ash trees for sawmills, the department reported. The first confirmed sighting of the beetles in Iowa came last May. They’re probably munching elsewhere in the state now, Pruisner said.
Often the borers are busy cutting off the trees’ food supply for five years before they are detected, despite the state’s system of traps and trees purposely damaged to see whether the beetles show up.
The borer, which has devastated forests in Michigan and other states, can fly only a few miles but is easily spread via firewood.
In Des Moines, Public Works Director Bill Stowe said the city removed about 40 young ash trees in the Brook Run neighborhood in northeast Des Moines. There are an estimated 10,000 ash trees in public parks and along city streets. City crews will replace ash trees with other species as removals continue, Stowe said. “It will be very selective and focused on younger trees where we can easily get in and out and plant a replacement tree without a lot of canopy loss.”
City Councilman Skip Moore wants to spread the financial pain over many years. Moore, who retired as Des Moines’ longtime forester after he was elected in December 2009, said he sees no choice. Cedar Rapids plans to cut down more than 300 ash trees over the next three months. The city has identified 520 trees at 440 sites that need to be removed. Altogether, the city has 9,000 to 12,000 ash trees along city streets, plus those in parks.
Iowa State University removed several dozen ash trees in a bid to reduce its concentration from 20 percent of campus trees to 8 percent, Bruemmer said. The trees will be replaced with other species. At Saylorville, crews are cutting down selected ash trees, even healthy ones, in part because they account for 40 percent of the trees at some campgrounds, said forester Brian Nail. It would mean less shade later if they aren’t replaced now.
Polk County found about 775 ash trees in high-use areas such as parks, campgrounds, golf courses. About 10 percent already have been cut down, said Mark Dungan, natural resources manager for Polk County Conservation. Ankeny passed a moratorium on ash tree planting two years ago, said Todd Redenius, parks and recreation director. The suburb plans to cut down some ash trees before the borer’s arrival.
Related Resources:
The Des Moines Register- Iowa takes an ax to ash trees
Trees Forever