Wednesday, November 17, 2010

A Question of Trees

An Unusual Storm
The tree had to come down.

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.

Related Posts:
A Day in the Country
Why We Should Garden with Biodiversity in Mind
Gardeners' Work
Strengthening the Biotic Community
An Excellent, Timeless Book

Update: Cross posted at Energy Bulletin.

10 comments:

Heather said...

That's too bad about your tree but I like your alternative much better.

We had a 'Crimson King' Norway Maple (the one with the wine colored leaves) in our yard when we moved in and immediately cut it down. I have since been cutting and eradicating 6-10 ft high seedlings (which are green leaved) in our yard from this tree. One characteristic of the Norway maple is the milky sap that will flow from the end of the petiole if you break off the leaf from the branch. Good way to check in case it's a sugar or red maple.

Don Plummer said...

Adrian:
Sternberg and Wilson's book is great! I have a copy. Too bad it's out of print (at least I think it is).

I've got a rather large lot as suburban lots go, so I've planted many trees. All are natives and most I've started from seed: paw paw, persimmon, redbud, flowering dogwood, red maple, white ash, Kentucky coffee tree, hackberry, and two oaks: chestnut and swamp white.

The US lost more tree acreage btw. 2000 and 2005 than Brazil lost rain forest? That's a fascinating--and disturbing--statistic.

If that's true, however, then I suspect you may have left out one of the chief causes. You wrote about farmers cutting hedgerows, clear cutting for timber, and urban sprawl. What might be causing the greatest loss of timberland in the USA is mountaintop removal coal mining.

Edith Hope said...

Dear Adrian, Great minds as they say.....Only recently I wrote about trees, their majesty, their ability to transform a garden and their beauty. But, the powerful points you raise here are so very true and act as warnings for all who may plant a tree without thinking fully of all the implications.

Adrian Ayres Fisher said...

Heather, we have a crimson king on the parkway, and aren't allowed to cut it down. Good point about the milky sap.

Don, your property sounds great. I left out mountaintop removal because I feel like I mention it too much. Maybe I'll put it back in.

Edith Hope, I'll come visit your blog and read what you wrote.

Dave Coulter said...

Very nice. Go oaks, go!

Anonymous said...

Nothing feels as satisfying in the same way as planting a tree--and better yet, the right tree. Lots of thought and information in this piece. I look forward to urging your bur oak to grow.

MRG

Steve Parr said...

I really enjoyed reading your thought process about which tree you decided to choose.

I would like to share a similar story and thought process. I live in Chatham, Ontario, which has a climate like Illinois but probably a bit moderated because we live 20 km north of Lake Erie.

I grew up planting norway maples because they were so easy! The seedlings grew everywhere (like weeds...) Over time as I observed and learned about other trees I gravitated to native species. In a nearby Provincial Park there are 150 year old oaks that I never noticed in my youth but now I stop and marvel at them each time I go there.

I each of the two homes we have owned the front yard included a norway maple. 12 years ago I was able to have the city remove it, but 7 years ago I had to do it myself.

My kids and my wife and I volunteered to help plant 10,000 acorns one spring morning as part of a project to restore a farm field back to forest. We brought some acorns home and I carefully planted them in an enclosure to keep the squirrels and rabbits away from the seedlings. Meanwhile, my son planted one acorn in the front garden without me knowing. It grew fine in spite of not being protected. Six months later when we moved to our current house we brought along my son's tree in a pot. In March 2004 we cut down the existing norway maple in the front yard. In July 04 my son and I planted "his" tree in the spot vacated by the maple even though it was only six inches tall.

It has survived well and is now about 20 ft tall!

I did not know at the time, but the tree my son planted is a....Burr Oak. Each year our three children get their picture taken in front of the oak tree on the first day of school.

Adrian Ayres Fisher said...

HiSteve,

Thank you for your inspiring story.

Steve Parr said...

To further solidify the choice of oak trees:

Quercus—Oaks support an astounding 543 species of Lepidoptera, including Polyphemus and Imperial moths, Banded Hairstreak, Striped Hairstreak, White M Hairstreak, Juvenal’s Duskywing, and Horace’s Duskywing

This is taken from Ecosystem Gardening: Top 10 Best Woody Plants in Ecosystem Gardening

Adrian Ayres Fisher said...

Thanks for the reference. Yeah, pretty much everyone should plant an oak!