Hardwood Forest Ecological System
The Hardwood Forest Ecological System occurs in both extended stretches and small patches along steep slopes at Rock Creek Park, most commonly northwest-facing and above streams.
Natural Communities in This Ecological System
There is only one natural community in the Hardwood Forest Ecological System at Rock Creek Park—the Oak – Beech / Heath Forest.
American beech in the canopy distinguishes this ecological system from the Dry Oak - Pine Forest Ecological System that's found on drier hilltops and some upper slopes. A scarcity of moisture-loving plant species and herbaceous plants (such as ferns, grasses, and flowers) distinguishes it from the Mesic Hardwood Forest Ecological System.
Tip: to see ecological systems on the interactive map of Rock Creek Park, use Layers On/Off to switch the main data layer to Ecological Systems.
Images of This Ecological System
In Rock Creek Park, the Hardwood Forest Ecological System is usually found on steep, rocky slopes, most commonly northwest-facing and above streams. Soils don’t have a chance to accumulate here before being washed away by rain or pulled downhill by gravity.
The slopes are underlain by acidic bedrock, which often protrudes above the surface as rock outcrops. In a few places, the Hardwood Forest Ecological System may grow over ancient river gravels that have washed and tumbled downslope from some of the hilltops in Rock Creek Park. Ecobit: Ridgetop River Terrace Riddle
This physical setting creates soils that are acidic, infertile, shallow, and fairly dry. Plants that live in this ecological system must make do with what little soil and moisture they can find. Dry-site oaks, including chestnut oaks, and American beech form the canopy, and heath-family shrubs, including mountain laurel, form the shrub layer. You won’t see many non-woody plants such as ferns, grasses, and wildflowers, because they have a hard time competing against the trees and shrubs for the limited amount of soil and moisture.
Where to See It in Rock Creek Park
Natural Processes That Maintain This System
Natural processes are responsible for maintaining the character of an ecological system.
Because the Hardwood Forest Ecological System grows on steep slopes in Rock Creek Park, erosion is a powerful natural process. The effects of rain and gravity prevent much soil from accumulating. Plants that grow here are shallow-rooted and prone to falling during storms. Windthrown trees open these forested slopes to sunlight—enough to allow the next generation of sun-loving oaks to mature.
Fire or Not?
Fire was probably infrequent in the Hardwood Forest Ecological System in Rock Creek Park in the past, as attested to by the presence of fire-intolerant species such as American beech (a prominent member of the forest canopy) and red maple.
Although the heath-family shrubs so abundant in this drought-prone habitat have flammable foliage and stems, the landscape position probably kept fire from becoming an important natural process here. The steep slopes are typically above creeks or moist floodplains where fire would be unlikely to start. Fire might start in the dry hilltops above (in the Dry Oak - Pine Forest Ecological System), but fire doesn’t usually travel downhill. In addition, the deep, moist ravines dissecting the landscape would act as natural firebreaks.
Ecological Threats to This System
Over-Browsing by Deer
The large population of white-tailed deer at Rock Creek Park may help to shift the proportions of oak to non-oak tree species in the Hardwood Forest Ecological System. Because deer seem to selectively over-browse oak seedlings, American beech and red maple may gain prominence in the forest canopies of this ecological system, which could be bad news for the wildlife that relies on oak trees and their acorns. Read more about the population dynamics of white-tailed deer in Ecology Basics.
Non-Native Invasive Plants
The Hardwood Forest Ecological System is somewhat resistant to invasion by non-native plants because of the difficult growing conditions—shallow, erosion-prone, and nutrient-poor soils. However, some non-native invasive plants take root even here, including
Read more about non-native invasive plants of Rock Creek Park.
Range Beyond Rock Creek Park
Although it extends into the Piedmont at Rock Creek Park, this system primarily occurs in the northern Atlantic Coastal Plain, often on dry, rolling uplands over coarse, unconsolidated sediments, occupying areas as large as thousands of acres. It ranges from Massachusetts and Long Island, New York (and in places all the way to southern Maine), south to the Coastal Plain and Piedmont portions of Maryland and Virginia, as far south as the James River.