Trees for the Future

“The Times They Are A-Changin'”

For those of you who follow my column, I am picking up where I left off last month. During a tribute to Bob Dylan at the 1997 Kennedy Center Honors, Bruce Springsteen spoke of the meaning of this titled article, a Bob Dylan song. Springsteen succinctly described its meaning as a “struggle for social justice in America”. And while this article has nothing to do with political or social change, it has everything to do with climatic change. Recently I have been involved in talks about trees for the future. Specifically trees that are struggling to adapt to our warming climates.

One fascinating study is being conducted at the Chicago Botanic Garden. “Andrew C. Bell, Ph.D., serves as curator of woody plants and is responsible for managing the development of the Garden’s tree and shrub collections. Dr. Bell’s work includes evaluating and promoting woody plants for sustainable landscapes and studying the effects of climate change on urban street trees.” (my.chicagobotanic.org/science_conservation/trees-for-2050/) Finding trees, now growing in the Garden, which will continue to do well in a warming urban environment, is paramount. The study takes a candid look at some trees growing at the “northern edge of their hardiness” through the year 2050 and beyond. The hard truth is that further data suggests that by 2080 “only 11 percent of the initial trees would continue to do well in Chicago and the upper Midwest.”

The realization is that many trees we are now familiar with may not be around and those we are less familiar with will be. Stephen Schuckman, my long time friend and owner of First Mountain Arboriculture has his MA in botany and is an ISA certified arborist. He shared with me two websites:

USDA Forest Service website, www.fs.fed.us/ne/delaware/atlas/ shows a climate change for 80 Forest Tree Species of the Eastern United States and www.nrs.fs.fed.us/atlas/ has new updates for climate change for trees and birds. The websites are as enlightening as they are scary. Take Sugar Maple, Acer saccharum, for example: the projected models have this tree all but gone in the years ahead. Steve says, “it’s fruitless to plant Sugar Maples at this point” and poses the questions; with this tree gone what will happen to the lumber and maple syrup that this tree provides? Dr. Bell points out two other trees that did not perform well in their study: American Linden, Tilia americana and Shagbark Hickory, Carya ovata.

What we also can take away from these studies, however, are trees that have performed well. Kentucky Coffeetree, Gymnocladus dioicus scored high marks. One of the largest trees in Eastern North America, Kentucky Coffeetree is a great candidate for street tree planting as well as residential and park settings. A wonderful native that has been touted as tolerant to the worst stresses nature and humanity have to offer. Kentucky Coffeetree has rich blue-green bipinnately compound leaves that finish yellow in the autumn. Two deciduous conifers that also performed well were common Baldcypress, Taxodium distichum and Ginkgo, Ginkgo biloba. Baldcypress offers a tall, columnar to pyramidal habit with rich green feather-like foliage. It is this foliage that turns rusty orange in the fall. Fibrous reddish brown bark has always captivated me in the winter months. And while Baldcypress makes an outstanding street tree, many use it as their “Go To Tree” for wet areas. Ginkgo, Ginkgo biloba is a tree that has survived the test of time. Existing unchanged for millions of years, Ginkgo has unique fan-shaped leaves that emerge a bright green and finish the year saffron yellow. Tolerant of just about any setting, Ginkgo makes a handsome, full tree over time and has long been my favorite. Finally, another top performer in the study, and there are others to talk about in a longer article, is Sweetgum, Liquidambar styraciflua. Sweetgum has forever been shunned in residential landscapes because of the “itchy balls” it drops on the lawn. The fruit alone has held back the potential of this tree. Interesting star-shaped green leaves turn shades of yellow, orange, red and purple in the fall. Efforts are being made to select “fruitless” varieties; perhaps ensuring this trees success as we all go forward.

My favorite Chinese proverb is: “The best time to plant a tree was 20 years ago. The second best time is now.” And while many take the quote as meaning it’s never too late to accomplish the things you want to in life, for purposes discussed here I am taking it more literally. We need to carefully select trees we plant today for future generations!