|An Unusual Storm|
During the “Chi-clone” of late October, which would have qualified as a Category 3 storm had it been over the ocean, a large limb split off from the Norway maple at the back of my house and fell in slow motion across my neighbor’s deck. She, outside checking on her planters, froze with disbelief and nearly got killed. The next day a couple of friendly, energetic men came over, scrambled up in the branches, commenced cutting and within three hours the tree was felled. Oh, the sudden light lancing through the western windows of my house!
The tree didn’t leave the premises, however. Two stout sections of trunk sit by the fence, acting as a mini-windbreak for a newly planted young shrub while awaiting a future use, possibly as the supports for a bench. A third that widens at the base like an elephant’s foot now sits, a water-filled flowerpot saucer on top, in a sunny spot between the pagoda dogwood and the prairie patch, to the birds’ delight. The rest of the tree went in the chipper and landed in a pile on the parkway to be shoveled and raked level: one more spot of lawn reduction accomplished. Some of the chopped-up, still green leaves went on the compost heap.
This summer I had been, again, looking at the tree with a critical eye—large Norway maple, too close to the house, a hazard in increasingly-common extreme weather events, annoyingly bountiful seeds and seedlings. But I generally don’t take out trees and shrubs just ‘cuz. Twenty years ago, when I still believed horticulture industry recommendations, I got the tree as part of a giveaway after a gardening lecture. Thrilled to get a free tree, I stuck the whip in the ground and over years, took photos of growing tree and children together. Eventually it provided cooling shade--and also turned out to be a shallow-rooted water thief beneath which neither grass nor flowers would willingly grow. Why, I wondered, was it so widely touted?
The Norway maple’s history turns out to be similar to that of many other exotic ornamentals that get imported, recommended, planted widely, and then, “escape” into the wild where— surprise!—with aggressive colonizing proclivities and few known predators, they make life difficult for native trees and forbs and the wildlife that depend on them. Quaker botanist John Bartram first imported Norway maples in 1756, and George Washington bought two from the Bartram nursery in 1792. It gained esteem as an easily-grown, durable shade tree that could thrive in unfortunate urban conditions, though I remain puzzled as to why it would be preferred, since the U. S. is nothing if not full of native maples and other perfectly good species.
|Norway Maple (Acer platanoides)|
Various cultivars came into wide use when the devastation of the elms denuded urban streets in the 1950s and 60s. Until the early 2000s, when Asian Longhorned Beetles hitched rides on packing cases, it was the preferred choice for individuals or municipalities wishing to purchase utilitarian ornamental trees. Even now, when many people think of a shade tree, they think of the Norway maple, without perhaps, knowing what it is. You may see one outside the window of the room where you are sitting at the moment. These days, many respected sources list it as an invasive species. The City of Chicago, with approximately twenty-one percent of its tree stock in Norway maples, discourages its use. Yet it is still widely offered for sale.
Nearly everyone agrees it is good to plant a tree, or trees. Even while North America lost more forest acreage between 2000 and 2005 than Brazil lost rainforest, caring Americans have applauded tree-planting efforts in other parts of the world: the African green wall, the Chinese tree-planting campaign, and farmer managed regeneration efforts in Burkina Faso. The U.S. has Arbor Day and national champion trees. Tree planting has long formed an important cultural meme, even as our farmers continue to sacrifice hedgerows and woodlots to the demands of corn and soy, even while clear-cutting for timber continues, mountain tops get removed, and urban development expands.
While so many agree on this, and while one of the first things the owner of a newly constructed house will often do is go to the big box store and bring home a tree to plant, many fail to remember the second part of the sentence. It’s good to plant a tree, and what we plant matters to the ecosystem. Homeowners (including my younger self) may not know any better. After all, knowledge of the local plant communities and native tree identification rarely form part of school curricula. Some landscape architects, garden designers and horticulture professionals forget this first principle, entranced by spatial design and tethered to industry trends. When a non-native tree is put in, it may have a nice columnar shape or good fall color or some other desirable visual characteristic. It may be pest-resistant and low maintenance. But in terms of design, it also helps de-localize and homogenize the U.S. landscape in the same way that large corporations nearly succeeded in homogenizing and de-localizing the American food industry during the twentieth century.
More importantly, each inappropriately chosen, inappropriately planted non-native tree tears a tiny hole in the four-dimensional fabric of our biotic community. Just as locally sourced organic food benefits the local community in myriad ways, compared to produce trucked in from elsewhere, so do locally grown native trees. Each time we plant an appropriate native, we are helping mend and strengthen the biotic community, of which our human community is a part. An appropriate native tree will join the biotic community, adding to its complexity, and thus its health and resiliency. It will also improve the overall design, as Wilhelm Miller, who originated the name “prairie style” for architecture and landscape design, first pointed out back in 1915 when he proselytized for the beauties of what he called the “characteristic local landscape.” (See my review of his book here.)
I am not advocating cutting down every non-native ornamental tree in the U.S. Even though I had discovered that Norway maples are invasive, I probably would not have had the one out back taken down, had not nature made the decision for me. Large properties have more room to play, and could possibly carry non-natives planted mainly for form. I’m thankful I can go visit the Morton Arboretum any time I want to walk among and study trees from parts of the world I’ll never visit. There are also fuzzy areas at the boundaries of the definitions of native and non-native. The ginkgo, that living fossil and popular street tree, was native to the U.S. 2 million years ago. Are we simply bringing it home after a long absence? When I see ginkgo seedlings from the parkway trees out front join the Norway maple seedlings among the blue-eyed grass and prairie dropseed, how should I feel? But these are special cases.
Now, nature has indeed decided for me. Questions arise. What native tree can I plant that will be appropriate to the yard while contributing to the ecosystem? That will be resilient in the face of the more frequent wind and rain events, drought and heat promised by the climate change models? That will eventually offer shade to help cool my house (important in a low carbon future), yet not act like a backyard bully?
These are important questions, especially when, as an urban/suburban gardener, you haven’t much room. I am jealous of some friends who live on a farm, who have enjoyed the luxury of planting an entire hickory grove. I wish I had the space of the twelve-acre property in Putnam County, Illinois, where I’m helping create a native-species-based landscape, and trees planted so far include several species of oak, sycamores, native maples, and redbuds to complement the existing black walnuts. (See earlier post here.)
But no. Discipline and restraint must prevail. Like so many other urban gardeners, I can pick exactly one large tree to help carry our living earth into the future. What I do on such a small scale may be trivial—but if every property owner planted appropriate native trees, a degraded regional urban/suburban ecosystem might begin to heal. So I’ve spent mornings looking at trees in neighborhood and forest preserve and evenings studying books such as Landscaping with Native Trees (by Jim Wilson and Guy Sternberg) and Forest Trees of Illinois. I’ve been considering the fact that my neighborhood was probably low prairie before European settlement. Hackberry or honeylocust? Kentucky coffeetree or catalpa? Red oak or white oak? I sound the names in my head and imagine each tree full grown in the yard.
Yet I know I’m just playing. The choice was made long ago—before I was born, before houses were built, before Father Marquette traveled up “my” river, the Des Plaines. The spirit of the place keeps whispering “bur oak,” a name echoed by several friends with whom I have spoken. Bur oak (Quercus macrocarpa), the fabled tree of the prairies that doesn’t mind wet feet or drought and finds clay subsoil tolerable. It moves into the prairie before the other oaks and survives where they can’t. Its strong limbs withstand strong winds, its acorns are edible and it can live 400 years. Bur oak. I know where to get some acorns and how to start one for free.
A Day in the Country
Why We Should Garden with Biodiversity in Mind
Strengthening the Biotic Community
An Excellent, Timeless Book
Update: Cross posted at Energy Bulletin.