ABOUT 15 YEAR AGO, when my husband and I bought a Victorian rowhouse in Washington, D.C., the "landscaping" consisted of a few scattered weeds. Not long after moving in, we began clearing and planting the tiny yard. There was room for only one tree, and we selected a Bradford pear. It turned out to be a terrible choice.
Even though this Asian native is planted by tens of thousands of homeowners across the country, I soon learned these trees attract very little wildlife. Butterflies ignored its blossoms. The neighborhood catbirds and robins shunned it. Only flocks of invasive starlings came to dine on its stone-hard fruit.
"Many people make this mistake," says D.C. landscape architect Mary Pat Rowan. "A serviceberry would have been better." These small native trees, also called juneberry or shadblow, entice more than two dozen species of birds to their fruit. Their beautiful spring foliage is equal to that of the Bradford pear, and their fall foliage is superior. One popular cultivated variety is called "Autumn Brilliance." A western species, Saskatoon serviceberry, also lures birds and grows as far north as central Alaska.
"The way I look at it, planting a native tree is always better," says Rowan. But many people--like me--buy trees that are originally from other parts of the world, even though these introduced species often offer very little to local wildlife. For example, the frequently recommended but nonnative Kousa dogwood has berries that are too big for most North American birds to swallow. Ted Stiles, a biology professor at New Jersey's Rutgers University, explains that Kousas evolved in Japan, where its large red fruits are mostly eaten by primates.
But our flowering dogwood--found in the East--has bird-sized berries that nourish nearly 75 species. And unlike the Kousa, this tree has another benefit: Its fruit is high in lipids--or fats--which provide birds with more energy than sugars do. In late summer and fall, songbirds use these native dogwood berries to help layer on the extra fat needed to fuel their long-distance migrations.
According to Rowan, another good reason to avoid introduced trees is that some exotics have the potential to escape suburbia and take over the surrounding woodlands. One especially bad actor is the Norway maple, a popular landscape tree in many parts of the country.
"They can alter the forest pretty severely," says Kurt Reinhart, a graduate student at the University of Montana who is finishing up his dissertation on the effects of Norway maples in riparian areas of the Northern Rockies. "Native species seem to decline whenever Norway maples gain a foothold," says Reinhart. "When you think about what you're going to plant in your yard, especially if you're near any natural areas, be very careful."
Instead of using a Norway maple, try a North American variety, such as sugar maple, big leaf maple, chalk maple or Rocky Mountain maple. "I don't recommend maples, though, unless a homeowner really wants one," says Rowan. She thinks one of the more than 50 species of oaks found in the United States and Canada is a better choice for wildlife. One of her favorites is willow oak. Other possibilities, depending on where you live, include coast live oak, chestnut oak, bur oak, pin oak, northern red oak and Arizona white oak.
Finding a native tree to landscape your yard often takes more effort, although some species--such as live oak--are readily available. Look for a nursery near you that specializes in natives. If you can't find one, horticultural or native plant societies can be a good resource.
Sometimes you can even turn up natives in your own backyard. Let a small corner of your property grow naturally, without disturbing the soil. An oak or pine tree may soon sprout. Also, if you're building a new home, don't let the contractor bulldoze the entire lot. They can work within a restricted space, saving much of the natural vegetation.
That's what we did when we moved from Washington to South Carolina. I remember standing between our house-in-progress and a 15-foot-tall black tupelo, talking to our builder. Since the tree was close to the house, he wanted to take it down. I was determined to save as many plants as possible, so it stayed. When autumn arrived, a pair of pileated woodpeckers began to visit that tupelo to gulp down its blue-black fruit. This time, I knew I had made the right choice.
South Carolina writer Doreen Cubie last wrote about native vines in the August/September issue. For more information about native plants and attracting wildlife to your yard, see Certified Wildlife Habitat.
Why Trees Are Worth Their Weight in Gold
For most, autumn is the season when we most notice trees. With their spectacular rich fall colors, it's hard not to appreciate their beauty. But trees in the yard are much more than decorations--or shelter for wildlife.
Researchers at the USDA Center for Urban Forest Research at the University of California–Davis say that a large tree can save homeowners and taxpayers as much as $160 a year. "A shade tree can reduce air-conditioning costs by up to 30 percent," says center director Greg McPherson. In fact, according to the San Francisco Tree Council, urban neighborhoods with mature trees can be up to 11 degrees cooler in summer than neighborhoods without trees.
In winter, trees can serve as windbreaks and reduce heating costs. The U.S. Bureau of Statistics reports that a line of evergreens can reduce cold-season fuel bills by up to 20 percent.
Trees are also important because they can intercept thousands of gallons of storm water a year--preventing flooding, filtering impurities and renewing groundwater. "It's possible for a 40-year-old ash tree in California to intercept more than 4,800 gallons of storm water and remove six pounds of air pollutants a year," says McPherson.
Further research indicates that an acre of mature trees can absorb enough carbon dioxide each year to offset the pollution of a car driven 26,000 miles.
But perhaps most significant to the homeowner is that mature trees increase the property value of a home, sometimes by as much as 10 percent.
It's sound proof that money does grow on trees.--Heidi Ridgley