Plants and Animals

Other Websites

Rock Creek Park

Explore this page

Plants

Although the canopy is mostly oak species today, American chestnut once grew in the canopy of this dry natural community, though probably not as commonly as in more mesic communities.1  American chestnut sprouts can be observed in the tall shrub layer of the Mixed Oak / Heath Forest off the Western Ridge Trail near Picnic Area 19. These sprouts can develop into small trees, but the chestnut blight, a non-native fungus, prevents most trees from maturing much beyond this point. Ecobit: Chestnut blight

Flowering dogwood, a beautiful shade-tolerant native tree in the understory, blooms in mid-spring and adds nutritional value to the landscape. Ecobit: Flowering Dogwood: Not Just a Pretty Face Sadly, dogwood anthracnose, an introduced fungus, can greatly damage and kill flowering dogwood. Ecobit: Dogwood Anthracnose As flowering dogwoods are lost, red maple, sassafras, and blackgum trees will likely take over their space in the understory.

Canopy Trees

The trees whose crowns intercept most of the sunlight in a forest stand. The uppermost layer of a forest.

Photo album

The canopy of the Mixed Oak / Heath Forest includes a combination of white oak, northern red oak, black oak, chestnut oak, and scarlet oak, as well as the occasional southern red oak, or pine tree.

Understory Trees

Small trees and young specimens of large trees growing beneath the canopy trees. Also called the subcanopy.

Photo album

Black cherry, flowering dogwood, sassafras, blackgum, mockernut hickory and red maple are shade-tolerant, drought-hardy understory trees—and American beech is becoming more common, perhaps because deer prefer to eat oak seedlings rather than American beech seedlings.

Sassafras leaves vary in shape from oval to three-lobed to mitten-shaped. When crushed, they smell like lemon. In fall, they turn brilliant yellow. Sassafras leaves, bark, and roots can be used for making tea. Sassafras tea is sold as a dietary supplement, but if consumed regularly, it can cause cancer and liver damage.

Shrubs, Saplings, and Vines

Shrubs, juvenile trees and vines at the right height to give birds and others a perch up off the ground but below the trees.

Photo album

Mapleleaf viburnum, common serviceberry, and American witch-hazel are typical tall shrubs here.

Heath family shrubs are also prevalent—blueberries, huckleberries, and pink azalea. Ecobit: Heaths

Greenbrier is another common low-lying shrub or thorny vine.

Low Plants (Field Layer)

Plants growing low to the ground. This includes small shrubs and tree seedlings.

Photo album

The field layer of this community is usually sparse, and typically characterized by hardy woody seedlings of canopy trees and shrubs instead of herbs. One herb that is occasionally seen is striped prince's-pine, a small, dark evergreen, waxy-leaved plant with a white stripe down the middle of each leaf. Native Americans made tea from this plant, and used crushed leaves for treating the sick and dressing sores and wounds. Another inconspicuous plant sometimes encountered in this natural community is cranefly orchid. These single-leaved plants appear in the fall or winter as scattered individuals on the forest floor, just above the leaf litter. The leaf (up to 4 inches long and 3 inches wide) of this plant can be a dull green on top, but underneath, it is deep purple. By the time a delicate spike of orchids blooms in the summer, the leaf is usually gone. The inconspicuous, half-inch, greenish to purple flowers resemble the crane fly, hence the name.

Non-Native Invasive Plant Species

Because of the meager living conditions here, not many non-native invasive plants would normally be a problem in this natural community. However, being bordered by residential neighborhoods, there is a constant supply of seeds from non-native plants. Read about them in Stewardship and Ecological Concerns of Rock Creek Park.

Notable Variations

Some occurrences of this natural community have scattered Virginia pines in the canopy, probably remnants of a pioneer pine forest that invaded an old pasture. A few Table Mountain pines (rare outside of the Appalachian mountains) are also scattered in Rock Creek Park’s Mixed Oak / Heath Forest.

These pines were more common in Rock Creek Park’s dry hilltop stands as late as the 1970s, when burning, logging, or plowing on these sites was more recent history.1  Now the pines are gradually dying out from old age and toppling over. As the old pines die out, new pine seedlings will be unable to get established without disturbances that introduce sunlight and expose mineral soil on the forest floor. Ecobit: Forest Succession—Clues to the Past

Animals

Eastern gray squirrel (Sciurus carolinensis) collecting nesting materials.
Photographer: Christopher Johnston

Keep an eye out in the Mixed Oak / Heath Forest for elusive red foxes, scampering chipmunks, woodpeckers, white-breasted nuthatches, white-tailed deer, and abundant gray squirrels, including black-colored ones. Ecobit: When Black Is Only Gray All of these animals and more feast on the abundant acorn crop supplied by the oak canopy. Look up in the oak trees for big leaf piles in the nooks of the branches—squirrel nests. A squirrel will chew off twigs or gather individual leaves in her mouth and carry them, one by one, up into the nest.

Standing and fallen dead trees serve as shelter, feeding, and resting sites for many animals in the Mixed Oak / Heath Forest.

Hillside blueberry, black huckleberry, and common serviceberry bushes provide cover for ground- and shrub-nesting birds, such as ovenbird. Their berries feed many types of wildlife.

Several animal species including deer eat sassafras leaves and twigs.

Horizontal lines of holes drilled into some of the tree trunks are evidence of yellow-bellied sapsucker, a woodpecker that spends the cooler months at Rock Creek Park, feeding on tree sap that it licks from the holes. The sap that runs from these holes—and insects that are trapped it—are important food sources for several other birds, bats, squirrels, and other animals.1

Hilltops that host the Mixed Oak / Heath Forest around the Nature Center at Rock Creek Park are locally known as migrant traps. One can often find migrating birds on these hilltops on early mornings during spring and fall bird migration. Hungry, tired, and cold after a long night of flying north, migrating birds may find insects enlivened by the first rays of the early morning sun.2  In fall, when insects are fewer, migrating birds feast on the fleshy fruits of mapleleaf viburnum and the occasional American holly shrub in this natural community.