Common (Translated Scientific) Name: Pin Oak - Swamp White Oak / Blackhaw / Whitegrass - Orange Jewelweed Wet Forest

Colloquial Name: Pin Oak - Swamp White Oak Seasonal Pond

Hierarchy Level:  Association

Type Concept: This wetland forest community is nearly endemic to hardpan soils of the Culpeper Basin in northern Virginia and Montgomery County, Maryland, with a few known outliers elsewhere in the Piedmont and the Ridge and Valley of Maryland, Virginia, and West Virginia. Habitats are shallow, seasonally flooded upland basins and wet, elongated bottoms along sluggish small streams with little or no active alluvial deposition. These habitats are characterized by shallow seasonal flooding induced by perched groundwater. Moderate hummock-and-hollow microtopography is often present, and maximum flooding depth is usually <25 cm (10 inches). A-horizon soils are dark brown to blackish, loamy clays which typically exhibit pronounced orange and white mottling and have moderate base status. This type is most common on areas underlain by diabase but also occurs on some soils weathered from siltstone and other metasedimentary substrates. The vegetation is an open forest or woodland dominated by Quercus palustris, mixtures of Quercus palustris and Quercus bicolor, or less frequently Quercus bicolor alone. Fraxinus pennsylvanica and Acer rubrum are the most frequent subcanopy trees. Viburnum prunifolium is the sole shrub dominant, while Smilax rotundifolia, Toxicodendron radicans, and Parthenocissus quinquefolia are common climbing and scrambling vines. The herb layer is usually open or sparse. The most constant and characteristic herbs are Leersia virginica, Cinna arundinacea, Impatiens capensis, Arisaema triphyllum, Symphyotrichum lateriflorum, Galium obtusum, Lycopus virginicus, and Juncus tenuis. Less constant herbs that can be locally common or abundant include Carex pellita, Carex festucacea, Dichanthelium acuminatum var. lindheimeri, Eleocharis tenuis var. tenuis, Glyceria striata, Scirpus georgianus, and Stachys pilosa var. arenicola. The invasive exotic Microstegium vimineum can be problematic on the drier edges and hummocks.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Classification of this association is supported by analysis of a 1250-plot regional dataset assembled for the NCR vegetation mapping project. In that analysis, this type was represented by 16 Virginia and Maryland plots. Field-collected qualitative data also exist for additional Virginia sites. This association is similar to the partly sympatric ~Quercus palustris - Quercus bicolor / Carex tribuloides - Carex radiata - (Carex squarrosa) Wet Forest (CEGL006497)$$, which occurs in backswamps, sloughs, wet flats, and depressions of large-stream and small-river floodplains in the same region. The relationship between these types is somewhat problematic. In their typical floristic expressions and habitats (i.e., floodplain backswamps vs. isolated upland basins), the two types are quite distinct. However, because of very low topographic relief in the Culpeper Basin, there is considerable ambiguity between alluvial and non-alluvial landforms, and composition of stands can be a continuous gradient between the typical expressions. The two groups do not separate well in cluster analysis, but do separate convincingly in ordinations studies. Ultimately, very intensive head-to-head analytical comparisons support the recognition of two types. However, some individual stands will be hard to assign by subjective field assessment. One stand located around a sinkhole depression pond in the Ridge and Valley of West Virginia is attributed to this association based on similar composition and non-alluvial landform. Atypical species at the West Virginia site include Cephalanthus occidentalisand Scirpus ancistrochaetus.

Similar NVC Types: No Data Available

note: No Data Available