Thousands of new urban trees threatened by drought

Urban Trees
Bob Belisle, an mobile equipment operator with the Minneapolis Park and Recreation Department, waters trees Wednesday, Sept. 12, 2012 along Sheridan Avenue N. The young trees were planted in the spring to replace those lost during the tornado last year. During dry conditions, like this summer, the water bags need to be filled once a week.
MPR Photo/Jennifer Simonson

Cities around the state routinely cut down and replace old and diseased trees, and spend a lot of time making sure the new trees have plenty of water in order to thrive. But this year's drought has made it hard to keep up.

The challenge is especially acute in north Minneapolis. There, the city planted 3,000 new trees to replace mature trees that were killed when a tornado ripped through the area last year. The planting represented about three-quarters of the city's $1.5 million budget for boulevard trees.

Keeping those trees alive is a priority, and the city has asked neighbors to help out.

All of the new boulevard trees here are anchored by sturdy green plastic bags holding 20 gallons of water, which seeps out gradually through tiny holes in the bottom.

As he worked his way down one street with a watering truck, parks worker Bob Belisle said he and other city workers fill the bags once every 10 days or two weeks.

When a tree goes in the ground, a packet goes on the door of the nearest house to ask for help with watering chores. But the city can't count on help from everyone.

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"It's sporadic, so we make sure we go around to all of them so they don't go completely dry," Belisle said.

Bob Belisle
Bob Belisle, a mobile equipment operator with the Minneapolis Park and Recreation Department, waters trees Wednesday, Sept. 12, 2012 along McNair Avenue N. The young trees were planted in the spring to replace those lost during the tornado last year. During dry conditions, like this summer, the water bags need to be filled once a week.
MPR Photo/Jennifer Simonson

It's been a tough year for trees, said Ralph Sievert, the city's head forester. Last fall was dry, and this year's early spring has made for a long growing season. Follow that up with a record hot summer, and many trees are struggling to survive.

"Trees can adapt, but when you add all those different cycles of dryness then they have harder time, especially some of these younger ones where the root system hasn't really gotten out there yet," Sievert said.

The city's pampering of these little trees is paying off: they're green and healthy-looking.

The neighborhood also shows off a new pattern in tree planting. City foresters have learned from the painful lessons of Dutch elm disease and now the Emerald ash borer, which have been killing off the state's ash trees, and they diversify the tree planting.

"It used to be if you were on a hackberry block, you got a hackberry. Now we intentionally try to mix things up a little bit," Sievert said. "Mainly because of getting that diverse type out there, so if you have an insect or disease specific pest you're not going to lose all the trees in that one area."

The trees on the Minneapolis block where Belisle is watering are maples and elms resistant to Dutch elm disease. Around the corner might be Kentucky coffeetrees, buckeyes, or oaks.

In St. Paul, the city contracts to plant about 3,000 trees each year, with a price tag of about a half-million dollars. This year, 100 of last year's plantings had to be replaced, many of them because of dry weather.

Urban Trees
Some newly planted trees in Minneapolis are tagged with small signs to remind residents to water them, like this tree along Sheridan Avenue N.
MPR Photo/Jennifer Simonson

And tree conditions aren't bad just in the Twin Cities. In Luverne, down in the southwest corner of the state, city tree inspector Ken Vos said rainfall is 7- to 8-inches below normal for the summer.

Vos describes Luverne as a town with 4,500 people and 4,500 boulevard trees. Every year his staff plants 100 new trees at a cost of $30,000 to the city. He said says about 25 young trees have died this summer. In spite of restrictions on water use, the city has been watering this year's plantings every week.

"They've all survived. It's the ones we planted last year, and the year before that and the year before that — the younger trees that we just can't begin to water them all," Vos said. "The new 100 that we planted this year we're still watering. We watered them again this week just because we don't want them to die."

Luverne, like most Minnesota cities, would like more help from homeowners. In Minneapolis, the parks department has calculated the cost of keeping a new tree alive. It would cost a homeowner about $6 to trickle water on a tree for two hours a week for the whole summer.