Swamp white oak basin swamp (S1)
Swamp white oak basin swamps contain an abundance of swamp white oak (Quercus bicolor) and are restricted to depressions and flats on marine sediments, other silty soils, and occasionally on sandy soils in the coastal zone and lower Merrimack River Valley. Species composition is often similar to red maple - Sphagnum basin swamps, but there is a notable shift towards swamp white oak in the canopy. Other differences include a shallower organic layer, less peat moss, and species indicative of silty soils or slightly enriched conditions such as musclewood, American elm, and poison ivy. They are also similar to swamp white oak floodplain forests in several respects. The primary differences from floodplain forests is the isolation from riverine flooding, presence of low to moderate hummocks, moderate to abundant amounts of Sphagnum moss, the lack of several floodplain plant associates, and the presence of typical basin swamp species (e.g., cinnamon fern and highbush blueberry).
These swamps have poorly drained mineral histic soils that are seasonally saturated or seasonally flooded with very little (or only a shallow) organic horizon (up to 5 cm). Plant strata are characterized by a variable amount of Sphagnum, a low to moderate herb layer, and a moderate to dense shrub layer. This community usually has standing water in the spring, and dries up by late summer.
Characteristic vegetation: Swamp white oak (Quercus bicolor) dominates in the canopy. Other species that are abundant or frequent in these swamps include cinnamon fern (Osmunda cinnamomea), highbush blueberry (Vaccinium corymbosum), and sheep laurel (Kalmia angustifolia). Herb cover is sparse. Species composition is similar to red maple - Sphagnum basin swamps, with some indicators of more enriched soil conditions imparted by the silty mineral soils, such as occasional musclewood (Carpinus caroliniana ssp. virginiana), American elm (Ulmus americana), northern arrowwood (Viburnum dentatum var. lucidum), and poison ivy (Toxicodendron radicans).
Species that are less abundant in this community (compared to swamp white oak floodplain forests), include musclewood, silky dogwood, elm, common woodreed, northern lady fern, and sensitive fern.
Good examples of this community occur at
Swamp white oak basin swamp at Stratham Hill Park (photo by Ben Kimball)
The mossy 'feet' of a swamp white oak in a basin swamp in Stratham (photo by Ben Kimball)