Windstorms that knock down trees and result in power failures seem to be coming more frequently, with two in the past few weeks alone. Observations in our corner of the world are in line with the scientific consensus on climate change, which indicate more intense storms and floods around the world.
Portland lost some 40 trees to mid-October’s windstorm. Beyond those, the city had 275 calls about tree damage, such as blown-down limbs, City Arborist Jeff Tarling said in a telephone interview later that month. On Halloween, the city lost another half dozen trees. These numbers are still in flux, as the city tries to assess damaged trees and to save as many as it can. (On the plus side, tropical storms have not been reaching Maine as hurricanes in the past few years, Tarling said. Let’s hope it stays that way.)
Still, at a time when gardeners are being asked to grow more trees, in part to store carbon to offset warming temperatures, it is disconcerting that more frequent storms seem to be undoing our efforts. In light of the changing weather patterns, we talked with Tarling about which trees he suggests homeowners consider planting and which to avoid.
Many of the trees that suffered storm death or damage last month were non-natives, Tarling said, which still had their leaves, thus catch more of the wind. As an example, he cited linden trees, which originate in Europe or Asia, depending on the species. “For the trees that blew down on Baxter Boulevard, lindens were high on the list,” Tarling said.
According to an article in Annals of Botany, leaf drop varies according to “local environmental effects, including temperature, soil moisture, frost and wind.” Few studies on the subject have been done, but Maine’s native trees would respond to these effects here, presumably, and “know” to drop their leaves earlier to avoid potential wind damage. Tarling said late leaf drop is the most significant factor in determining which trees are likely to be brought down in a storm. Trees planted in clay soil, he added, are also more likely to be blown down — the roots simply pulling up.
Then there are Norway maples. The city stopped planting them about 30 years ago, Tarling said, but 3,000 of the species still grow in Portland; the state now classifies them as invasive. Like lindens, Norway maples retain their leaves late into the season, making them vulnerable to wind. This one species alone causes about 80 percent of the city’s tree problems, Tarling said. He listed Callery pear (also known as the Bradford pear) as another import — the tree is native to Asia — that often sustains heavy damage in Maine’s fall storms. (The state has considered listing the Callery pear as invasive, but hasn’t yet.
And while ash trees are natives, Tarling says avoid those, too. While ashes are an attractive and useful tree, the destructive emerald ash borer was discovered in Payson Park this fall. The invasive, green beetle decimates ash populations, making now a less-than-ideal time to plant an ash tree here.
Which trees should a homeowner plant, then?
Oaks are OK, Tarling said, despite damage in recent years from the winter moth and browntail moth. He thinks oaks will survive these infestations. Oaks keep their leaves longer than maples, so are somewhat susceptible to wind damage. But the trees that suffer storm damage are usually older trees that already have some internal decay, he said. In particular, Tarling likes the swamp white oak, which prefers damp areas, transplants easily and turns orange in the fall.
He also suggests red maples, which come in many good cultivars (although avoid the October Glory, which holds onto its leaves longer), and the stately shagbark hickory. If you like birches, Tarling recommends the River birch.
Homeowners have more unusual options, too. The black tupelo, Nyssa sylvatica, is native to Maine, though Maine is at the northern edge of the tree’s range. The largest one recorded in the state was found growing wild in woods behind O’Donal’s Nursery in Gorham. Black tupelo can grow 75 feet tall and its shiny green leaves turn a bright reddish orange in fall.
Another zone-pushing native is catalpa, which grows 40 to 50 feet tall, has large leaves, clusters of orchid-like flowers in early summer and long seed pods. It is more common in the mid-Atlantic states than it is here. You can find it at local nurseries, but the Arbor Day Foundation offers bare-root catalpas at a significant discount.
Some non-native trees seem to be equipped to handle our storms, as well. The attractive, stately ginkgo, or maidenhair tree, which comes from Asia, thrives under difficult conditions so is often used as a street tree. Come fall, its leaves turn bright yellow. Tarling suggests magnolias and crab apples as good, smaller ornamental non-native trees that thrive in urban yards. I agree with him about the magnolia, but I am not a fan of cleaning up the crab apples that drop to the ground every fall.
Next time you are ready to plant a tree, first consider the changing weather patterns and which species are better-equipped to cope with the more destructive weather. Then go to your local nursery, describe the conditions where you want to plant the tree, and listen to their advice.
You will get an addition to your home that is likely to outlive you — and your children.
Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: tomatwell@me.com.
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