What do you get when you take Dutch elm disease and Mother Nature and mix them with $300,000 of park board money?
Answer: A grinding sound that consumes about 109,090 square inches of tree trunks and lasts all summer.
It is called stump grinding and the Minneapolis Park and Recreation Board will be providing it for the next five years at a cost of $300,000 per year.
“We put out a bid every year,” said Jim Hermann of the park board. “The bid is on price per diameter grind and this year we are paying two and a half to three dollars per inch.”
The winning bidder this year was the Minnesota Department of Forestry.
“We give them a list of the stumps and they go and grind them until the money runs out,” Hermann said. “It’s actually a good deal for the taxpayers because they go in grind the stump down, backfill the hole, and remove the sawdust if the homeowner has no use for it.”
Not only will the city of Minneapolis be grinding stumps this summer but the will also provide for the planting of 3,500 trees at the same cost as the stump removal.
Where this problem comes from is no mystery.
In 2004 and 2005 some 16,332 Minneapolis trees were lost to Dutch Elm disease, resulting in a backlog of tree stumps that need to be removed. According to the Minneapolis Tree Advisory Commission, around $5.75 million in annual urban forest benefits were lost and won’t be recovered for decades if ever.
In comparison, the Park Board spent an average of $183,000 annually on tree stump removals from 2000 to 2004. The number jumped dramatically when the board spent nearly $600,000 on stump removals in 2005 and $432,000 in 2006.
“We have been playing catch up for the past few years,” Hermann said. “It is tough because the money only goes so far.”
It’s important to remove stumps for several reasons. Probably the most important is to stop the spread of disease. While the trees themselves are not able to pass on Dutch elm disease, the rotting stump serves as a breeding ground for the disease-carrying insects.
Also, it’s important to plant of a new tree in the empty hole. “They do one of two types of grinds when removing a stump,” Hermann said. “The shallow and the deep are used depending on if they plan to replant or if they just plan on covering it up.”
According to Hermann the shallow grind is used in parks mostly when there is no plan to replant in the exact location of the last tree; the deep grind is mainly found on the boulevards so that new trees may be planted in the same spots.
According to the Minneapolis Tree Advisory Commission’s 2006 annual report, Minneapolis is home to 1.8 million trees of which nearly 200,000 are public boulevard trees that provide at least $24.9 million in quantifiable annual benefits. These benefits include annual energy savings of more than $6.8 million, reduced storm water runoff benefits equal to $9.1 million in savings, aesthetic and property value increases of at least $7.1 million and additional benefits for noise and air pollution reduction.
“The removal of the stumps is important for the city,” Hermann said. “The $300,000 may seem like a lot but without more funding we’ll be playing catch-up for years to come.”
Other major threats on the horizon to the urban forest include:
• Asian long-horned beetle: While this type of beetle has not yet been found in Minnesota the insect targets and kills most species of trees making it a huge threat. The only remedy is clear-cutting all trees for blocks around. Has been found in Chicago and New York.
• Emerald ash borer: This beetle attacks ash trees only and like the Asian long-horned beetle, the only effective remedy against this pest is clear-cutting all trees for blocks around. While this insect is not found in Minnesota yet, about 22 percent of Minneapolis trees are green ash.