Manassas Battlefield Park is located in Virginia's Piedmont, a region of mixed-deciduous/coniferous forests within which there is much variation. Soil type, microclimate, and other factors can influence the types of forests found here. Although the park is known for its meadows, several forest community types exist within MNBP. A 2002 study done by the Virginia Department of Conservation and Recreation found several classified forest types within the park. They are described below.

Piedmont/Mountain Swamp Forest: These wet forests occur in seasonally-flooded sloughs and back swamps in the Bull Run floodplain north and south of US Highway 29. They are completely inundated every 1 to 3 years, but generally contain standing water in winter and spring and are drier by summer. The canopy is dominated by Pin Oak, Swamp White Oak and Green Ash. Smaller trees commonly found are American Elm and Red Maple. Black Haw and American Hornbeam are common shrubs. Reeds and Sedges grow from the soggy, highly acidic soil.

Upland Depression Swamp: This community type is found in shallow, seasonally-flooded upland basins and along small stream bottoms such as Young's Branch. Pin Oak and Swamp White Oak make up the canopy; Green Ash, Red Maple, Persimmon and American Elm are understory trees found here. Hickories grow along the margins of these habitats. The shrub layer is composed mainly of Black Haw, and Poison Ivy and Virginia Creeper are commonly found clinging to the trunks of trees. The herb layer is mostly open, with various sedges and grasses, and flowers such as Jack-in-the-Pulpit emerge from the moderately acidic soil.

Piedmont/Mountain Bottomland Forest: These forests are found on elevated terraces and floodplain levees bordering streams in the park With well-drained strongly acidic soils with high mineral content, they are occasionally inundated with water for brief periods. The canopy contains Bitternut Hickory, Hackberry, Green Ash, Black Walnut, Tulip Poplar, Pin Oak, Shumard Oak, American Sycamore, and American Elm. Boxelder is dominant in the understory. Our native banana, Paw-Paw, can be found in the shrub layer, along with American Hornbeam and Spicebush. Close to the ground in the herb layer grow Wild Ginger, sedges, Lowland Brittle Fern, and Wood Nettle as well as wildflowers such as Virginia Bluebells, Golden Ragwort, Downy Yellow Violet, and Striped Violet.

Basic Mesic Forest: This forest type is confined to a very small area within the Park on a bluff bordering the inner edge of the Bull Run floodplain. Highly fertile, well drained, moist and only moderately acidic, the soils here support a canopy of Bitternut Hickory, White Ash, Hackberry, Chinkapin Oak (rare in other parts of the park), Northern Red Oak, and Slippery Elm. There are very few understory trees, but the shrub layer contains Paw-paw, Eastern Redbud, Spicebush and Bladdernut. A lush herb layer is dominated by Lowland Brittle Fern, Virginia Waterleaf, Nebraska Sedge, Wild Ginger, a variety of grasses, and flowers such as Green Violet, Harbinger of Spring, and Large-Seeded Forget-Me-Not.

Basic Oak-Hickory Forest: These forests are widespread in the park, occupying low ridges and upland where soils have a hardpan clay sublayer and are moderately to highly acidic. White Oak and Pignut Hickory dominate the canopy, along with Northern Red Oak and Red Hickory. Post Oak, White Ash, Mockernut Hickory, Black Walnut, and Black Oak are occasional canopy trees. The understory is home to young hickory and White Ash trees. Eastern Redbud, with its brilliant spring blossoms, is the most common small tree/shrub layer inhabitant, along with Easter Red Cedar, Flowering Dogwood, Eastern Hophornbeam, Slippery Elm, Hackberry, American Hornbeam and Fringetree. The shrub layer is home to a variety of dry site grasses and small plants such as Virginia Copperleaf, Snakeroot, Rattlesnake Fern, Wild Comfrey, and American Pennyroyal. Several flowers are also found here, among them Rue Anemone, Three-Lobed Violet, and Woodland Sunflower. These are only a sampling of the many species found, however. This forest type is the most diverse in the park.

Acidic Oak/Hickory Forest: This forest type is also widespread within the park, and is found on low ridges and rolling to flat uplands in extremely acidic soils. It is generally drier than the Basic Oak/Hickory Forest. White Oak is the leading dominant canopy tree. Black Oak, Red Oak, Red Hickory, Pignut Hickory and Scarlet Oak are occasional associates. In the understory, Hickories dominate, but Sassafras, Red Maple and Black Gum may also be found. Flowering Dogwood, Downy Serviceberry, Deerberry and young hickories make up the shrub layer. Low heath family shrubs such as Early Blueberry and Black Huckleberry populate the herb layer, along with dry site grasses and sedges. Some wildflowers found here include Large Summer Bluets and Solomon's Seal.

Eastern White Pine/Hardwood Forest: This forest type is found only in a small area on the west side of Bull Run northwest of the Stone Bridge on relatively steep slopes of a ravine system and bluff top along the stream. Extremely acidic and infertile soils make this a Pine-dominated community type, with Eastern White Pine and Eastern Hemlock leading, followed by various oaks such as Chestnut, White, Northern Red, and Scarlet. Virginia Pine is also present in the canopy. Red Maple and Black Gum are the primary understory species, but Flowering Dogwood, Sassafras, Mockernut Hickory, and young pines are also found. In the shrub layer, heath species such as Mountain Laurel, Black Huckleberry, Early Blueberry, and Deerberry are prevalent. The herb layer is very sparse, with only Northern Bracken Fern and Partridge Berry occasionally appearing.

Eastern Red Cedar Successional Forest: This forest type, which is short-lived, occurs around the park in former fields and clearings abandoned within the last 80 years. Clay rich, low nutrient soils support early successional species such as Eastern Red Cedar and Virginia Pine. Some stands are actually monocultures of one species or another; others are a mixed composition of the two. Older stands also contain Flowering Dogwood and various hardwood saplings in the understory. The herb layer is nearly bare on densely shaded sites where canopy trees grow close together. A successional forest is only temporary, however. As hardwoods in the understory grow upward and overshadow the pines in these stands, the forest type changes.

As northern Virginia becomes more and more developed, conservation of forest community types becomes a critical concern. Along with its vibrant meadows MNBP contains examples of many of the Culpeper Basin's forest habitats, thus providing for the conservation of diverse ecosystems in the region. MBNP's management of the landscape for historic preservation purposes goes hand in hand with protecting these forests.