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Taking on tree terrorists: St. Paul's new trees fight Emerald Ash Borer
Call it a pre-emptive strike against hostile invaders.
First discovered in Minnesota in the South Saint Anthony neighborhood of St. Paul in May 2009, the Emerald Ash Borer (EAB) is an invasive pest that has already laid waste to urban forests in cities across Michigan. The adult beetle lays its eggs underneath the bark of healthy ash trees, killing them over the course of a few years as their larvae feed on the tree from the inside.
Though difficult to detect initially, EAB spreads quickly and it could more than decimate the city of St. Paul's tree population, which the city estimates to be 25 to 30 percent ash, within the next decade.
"We're not going to be able to beat this bug," said Cy Kosel, Acting Operations Manager for the City of St. Paul's Parks and Recreation Department. "We have been told it's just a matter of time."
The Minnesota Department of Agriculture awarded the city a $722,600 grant to start strategic maneuvers early.
In an effort to soften the upcoming blow to the city's public trees and the resources it takes to manage them, the parks department is managing a citywide "structured removal" of ash trees from boulevards even though they are not yet infested.
The city is concentrating on boulevards, because that's where widespread tree death could cause the most damage to vehicles, property, and people. Unfortunately, it's also where trees are seen the most. "[The removal of trees] is making some of the streets look pretty sad," a commenter on an online neighborhood forum posted recently.
Since spring 2009, the city has removed more than 1000 ash trees from city boulevards. So far the removal has been distributed evenly across city wards, but some areas such as Highland, Hazel Park, and parts of Como have a heavier concentration of ash planted, and will end up looking barer.
For every ash tree removed, a new species is being put in its place. As replanting continues, the blocks will become more diverse to help reduce future threats of pests or disease knocking out swaths of the city's trees. In the past, one tree species has been "mono-cropped" for up to six blocks at a time, but Kosel says urban planners have learned their lesson. Twice.
After Dutch Elm disease hit city blocks in the 1970s, urban foresters saw ash as a "silver bullet" for elm replacement, Kosel says. Ironically, that put the city in the predicament it is in today.
Kosel explained that the new strategy plants pairs of trees together and switches pairs each block. "The key is more diversity, more switching of tree types," Kosel said.
Not far from the site of the original infestation, Barbara Spears, a trained urban forester, lives in the Hamline-Midway neighborhood. Upon the discovery of an EAB-infested ash within the neighborhood's borders, Spears' training told her that the health of the residential ash trees in her neighborhood could soon be on the decline, and fast.
Unlike the city, however, Spears didn't know how hard hit her neighbors could be as the beetle spread; there aren't any numbers on how many ash trees are planted on private property.
So, with Spears' guidance and some funding from the Hamline Midway Coalition, 25 volunteers (including a four-year-old and a six-year-old) undertook a "tree census." They counted all 6700 trees in the neighborhood, 680 of which were ash species.
"They walk their dogs, they walk their kids, but they never thought about the trees, so that's why they got involved. [They] came away with a better appreciation of our urban forest," Spears said.
After the census was complete, the group offered free replacement trees to property owners with ash trees and enough room to plant a replacement large shade tree species on their lot. Spears said they distributed more than 60 trees to homeowners in the neighborhood, and will offer them again in the spring.
Through a partnership with Outback nursery, they were able to offer all native tree species "We want to emphasize native species in the neighborhood, especially in the backyard," Spears said.
Though she recognizes she has a degree in Urban Forestry to guide her, she hopes her team's project can serve as a model for other communities that may soon be affected by EAB. "The resources are out there for communities to do this," Spears said, but "it just takes people to just take the time. [Without] Barb just doing it out of her home, it wouldn't have happened."
And it's worth more than just keeping the sidewalks shady, Spears said, "[It's] a chance to connect with your neighbors and rally around the community and the community of trees."
©2010 Sarah Vig