By Bill Sublette
Piedmont Master Gardener
Fall is almost upon us, bringing with it the ideal time to add trees to our landscapes. In addition to providing shade and beauty, increasing tree cover in our community provides a host of environmental, economic and health benefits. According to the Virginia Department of Forestry, neighborhoods with a robust tree canopy have lower crime rates, less air pollution, lower energy costs and higher property values. Planting a tree in your yard is good for all of us.
It’s also a decades-long commitment. When we plant a tree today, we should keep in mind the challenges it will face in the years ahead. This means selecting a tree that can weather the expected impacts of climate change.
Dr. Eric Wiseman, associate professor of urban forestry at Virginia Tech, is working with Extension Master Gardeners and Tree Stewards to help Virginia localities create and expand tree canopies that are ready for what the future holds. He recommends looking to our coastal plain and southward to identify tree species that can stand up to the vagaries of a changing climate, including not only rising temperatures but also more severe storms and erratic precipitation patterns that can swing from droughts to rainfalls that drop inches in a day.
“As we begin to think about creating resilient urban forests in the future, we should be looking at species that are thriving further south and able to tolerate the changing climate that may be coming to our area,” explained Wiseman, who worked as a Certified Arborist before entering academe.
This isn’t simply a matter of picking a species from, say, central Georgia and plopping it in Albemarle County. Even as average temperatures in our area rise over time, we’re still likely to experience the occasional night when the mercury dips into single digits or even below zero. Such an event would spell the end for a tree that currently won’t survive north of Atlanta.
So, Wiseman is urging us to select highly adaptable trees that will thrive here right now and continue to thrive as conditions change. For our area, he suggests a range of candidates, including natives of the Southeast as well as non-natives that “play nice” and won’t invade our natural areas. Many are already familiar members of our local treescapes. Here are some examples.
Ginkgo biloba. Often described as “living fossils,” the Ginkgoes among us today stem from a line that stretches back some 200 million years. This tree is beloved for its fan-shaped leaves and its brilliant autumn display. Examples in our area include the University’s iconic Pratt Gingko, planted in 1860 and named for U.Va.’s first superintendent of buildings and grounds. It stands northwest of the Rotunda and is famous for dropping its leaves virtually all at once to create a carpet of gold. Ginkgos are dioecious, meaning there are male and female trees. Choose a male tree if you wish to avoid the odor of the females’ fleshy seed coverings.
Bald Cypress (Taxodium distichum) and its more southernly cousin Pond Cypress (Taxodium ascendens). These deciduous conifers drop their needles in the fall. Although associated with swamplands, they make fine landscape trees in dry upland areas. In fact, the Charlottesville Area Tree Stewards recently planted bald cypresses on a hillside in Mint Springs Valley Park. To see a mature specimen, look up from the intersection of University and Rugby Avenues. You will see several huge bald cypresses toward the University Chapel. These trees are fast growers and long-lived. The late “Big Mama” in what is now Cypress Bridge Swamp Natural Area Preserve between Emporia and Suffolk was believed to be at least 1,500 years old when it died in 2008.
Kentucky Coffeetree (Gymnocladus dioicus). This tough, handsome tree is known for its lush and long compound leaves (leaves made up of smaller leaflets), its fragrant flowers, and the beanlike pods that drop from the females. The seeds inside look like coffee beans and were roasted for food by Native Americans and made into a coffee-like brew by early settlers. In Charlottesville, you will find Kentucky Coffeetrees along the south side of U.S. 250 East approaching Interstate 64 from the Pantops area. Don’t eat the seeds right off the tree; they are toxic if not cooked.
Swamp Chestnut Oak (Quercus michauxii). As its name suggests, this fast-growing member of the White Oak group is happy to live with wet feet, but it will also grow vigorously in dry areas. Just take a look at the young example in front of the reconstructed outbuildings at James Monroe’s Highland. Right now, it’s showing the pyramidal form typical of youthful trees, but it will spread more broadly as it matures. Wiseman also recommends the Swamp White Oak (Quercus bicolor) and the Overcup Oak (Quercus lyrata), a member of the White Oak group suitable for smaller spaces.
Shumard Oak (Quercus shumardii). Also known as the Swamp Red Oak, this is another coastal or bottomland tree that grows well in our “mesic” (moderately dry) terrain. Often planted as a street tree, it’s admired for its dark, shiny leaves and for its open, domed-shaped crown at maturity. A magnificent example can be found at the southeast corner of the Jefferson-Madison Regional Library on Market Street, designated a Landmark Tree by the Charlottesville Area Tree Stewards. Another recommended member of the Red Oak group is the Nuttall Oak (Quercus nuttalli or Quercus texana), an adaptable floodplain tree considered a sprinter in the growth department. It’s also a popular choice as a street tree.
Honey Locust (Gleditsia triacanthos). This lowland tree has naturalized in our area and seems to take whatever nature throws at it, including drought, high winds and poor soil. Its sharp spikes are even more menacing than those of the more familiar Black Locust (Robinia pseudoacacia). Its large, leathery seedpods are distinctive as well. You will see one of these trees on the right as you walk into the Ivy Creek Natural Area, but don’t try to climb it.
London Planetree (Platanus x acerifolia or Platanus x hispanica). This cross between the American Sycamore (P. occidentalis) and Oriental Planetree (P. orientalis) has been a staple of urban streetscapes for centuries, thanks to its reputed ability to withstand pollution and much more. Like its American forebear, it displays mottled, peeling bark, but it can be told apart by its double rather than single prickly fruiting balls and its more deeply lobed leaves. A stately row of London Planetrees can be seen along a road off the right of Fifth Street SW heading south, just before the I-64 exit.
Other durable trees and shrubs on Wiseman’s recommended list include Black Gum (Nyssa sylvatica), Hawthorns (Crataegus species), Sweetbay Magnolia (Magnolia virginiana) and southern conifers such as the Pond Pine (Pinus serotina) and the Longleaf Pine (Pinus palustris), which once covered millions of acres of the southeastern coastal plain, stretching from Tidewater Virginia to Texas.
Wiseman also warns against planting trees that are likely to struggle in a changing climate. Highland conifers such as the Balsam Fir (Abies balsamea) and Fraser Fir (Abies fraseri) are already imperiled by pest pressures and are sure to fare poorly at our lower altitudes. Likewise, he urges caution when planting the cool-climate Sugar Maple (Acer saccharum). Site it away from heat sources such as a south-facing wall or an asphalt parking lot or driveway. As an alternative, Wiseman recommends the Southern Sugar Maple (Acer barbatum or Acer floridanum), a southeastern native that offers a colorful fall display and tolerates heat and drought once established. And steer clear of the Eastern White Pine (Pinus strobus), which falls prey to storms when mature. Those of us who lost White Pines in the 2012 derecho can attest to that.
Furthermore, Wiseman emphasizes that the benefits of planting a tree come with the obligation to take care of it. “There is strong evidence that trees on a preventive maintenance regimen will be more sturdy in storms and more tolerant of any form of urban stress,” he noted. Consistent, long-term care—including appropriate pruning—is important not only for our community’s tree canopy but also for all of us who live under it.
For more detailed descriptions of the recommended trees, see The Tree Book by Michael A. Dirr and Keith S. Warren, or search online for the Missouri Botanical Garden’s Plant Finder or the Virginia Tech Dendrology Factsheets.