Rock Creek Park Vines

Native vines are an important part of the Rock Creek Park forests, but they sometimes get tangled up in the fight against non-native invasive plants. Here’s why we should even “embrace” poison ivy, while being wary of the sweet-smelling Japanese honeysuckle vine.

Vines in Rock Creek Park

The tube-shaped flowers of the native trumpet creeper vine are a favorite of hummingbirds.

NPS/Nortrup

Rock Creek Park is one of the largest natural parks in an urban center. At approximately 2,000 acres, it is twice as big as New York’s Central Park and is 81% forested. The park was established in 1890 to protect the natural resources of what was then a rural retreat at the edge of a growing city.
To protect this treasure, National Park Service staff from the Inventory and Monitoring (I&M) program monitors for­ests in Rock Creek Park, tracking the growth of park vegeta­tion including trees and vines.
Monitoring takes place at nineteen plots in Rock Creek where every tree is inspected for the presence of vines and the species of each vine is recorded. This brief presents the most recent data on vines found in I&M forest plots in Rock Creek.

What's a Non-Native Invasive Vine?

A vine is a weak-stemmed plant that requires other plants or structures to support itself and grow upward.
Non-native plants are plants introduced from other regions or habitats. They’re sometimes called weeds, exotics, or invasives. Non-native invasives can disrupt naturally-balanced plant and animal communities by growing aggressively, adapting quickly to new habitats, and multiplying. Wildlife that is dependent on native plants is often unable to adapt and is forced to migrate to the ever shrinking suitable habitat that remains.

Rock Creek's Top 10 Vines

The 10 most common vines on trees in Rock Creek Park.

This graph shows the ten most widespread vine species in Rock Creek Park. Half are natives (in blue) and half are non-native, invasives (in red). Overall, vine numbers are increasing across the National Capital Region, with non-native, invasives like Japanese honeysuckle, oriental bittersweet, and winter creeper spreading faster than native vine species.

Vines & Wildlife

Vines provide an important food resource for birds, deer, and native moth species. Some vines, such as the native frost grape (Vitis vulpina), can be one of the only food sources for resident birds during the cold winter months. Vines can also offer nesting material for birds from their shredded bark and they provide shelter for many mammals.

Embracing Poison Ivy!?!

Poison ivy, "leaves of three, leave them be."

NPS/Nortrup

Typically, poison ivy (Toxicodendron radicans) gets a bad reputation for being a nuisance that causes itchy rashes in humans. However, it is actually an important food source for many wildlife species. Eastern cottontail rabbits, white-tailed deer, and muskrats have been known to eat the leaves and stems. Poison ivy’s fruit is an especially important food source for many animals such as crows, bluebirds, and turkeys. Birds, such as northern cardinals and American goldfinches use the vine’s thread-like hairs to build their nests. Poison ivy’s leaves can also provide shelter for a variety of small animals and provides food for many insect species as well. Despite all of the negative attention it receives, poison ivy is a welcome native. For these reasons, Rock Creek Park only manages poison ivy on trails and in areas where it is directly affecting park visitors.

Twining and Clinging

Many non-native, invasive vines such as Oriental bittersweet (Celastrus orbiculatus) and Japanese honeysuckle (Lonicera japonica) are known to strangle and kill trees. They do so by twining tightly around parts of the tree, cutting through the bark, and blocking the tree’s internal flow of water and nutrients. This twining trait is generally more common for non-native, invasive species and can stunt tree growth, as well as increase tree mortality.
Other methods of climbing are less destructive. Native vines like Virginia creeper (Parthenocissus quinquefolia) will climb high into the tree canopy by adhesively clinging to the bark. Native grape vines will climb trees using tendrils that grasp onto branches and other supporting objects. Unlike strangling, twining vines, grapes will hang loosely from the trees and normally do not choke their host tree.

Effects of Vines

Vines covering a forest edge.

NPS/Nortrup

All vines have the potential to spread out and cover branches, blocking needed sunlight and eventually killing a tree. An infested tree can show signs of decline for several years before it dies. Although the death of a tree can allow for more sunlight to reach the forest floor, that sunlight can fuel both native vine species and harmful non-native, invasives. Non-native invasives have successfully exploited these opportunities and are increasing at a faster rate than their native competitors.
As vines grow higher onto tree branches and stems, their sheer weight is capable of snapping large limbs. The loss of these branches means a loss of leaves and reduces the ability of the tree to gain energy from the sun. Resulting tree death can lead to a less biodiverse forest and an unhealthy mature tree canopy. Additionally, large falling branches can pose a safety and financial hazard for the park and its visitors.

Help Lend a Hand

We welcome you to join us as a volunteer to help control these non-native, invasive vines. You can join Rock Creek Park staff or one of the park’s partner groups (e.g. Dumbarton Oaks Park Conservancy or Rock Creek Conservancy) to assist on removals. But remember, removing vines in Rock Creek without authorization is illegal and poor methods or mis-identification of species can cause great harm.
You can browse a helpful, photo-rich identification key to vines in Rock Creek Park. To learn more about NCRN forest monitoring, visit the NCRN website.