Common (Translated Scientific) Name: (Common Buttonbush) / Threeway Sedge - (Swamp Smartweed, Creeping Mannagrass, Marsh Mermaidweed) Marsh

Colloquial Name: Central Appalachian Montane Depression Pond (Threeway Sedge - Buttonbush Type)

Hierarchy Level:  Association

Type Concept: This community occurs in mostly seasonally flooded (rarely semipermanently flooded) depression ponds in the Central Appalachian, Ridge and Valley, and Northern Blue Ridge provinces. Habitats are thought to have formed by solution or collapse of underlying bedrock strata. Occurrences range from 470 m (1540 feet) to over 900 m (3000 feet) elevation. Topographic position varies from ridge crests to mountain-foot alluvial. Ridge and Valley ponds developed on sideslope benches resulting from landsliding and catastrophic slope failure are often referred to as "sag ponds." Ponds developed by solution and collapse of carbonate rocks underlying acidic alluvial and colluvial materials eroded from the Blue Ridge and deposited along the eastern edge of the Great Valley of Virginia in massive alluvial fans are often referred to as "Shenandoah Valley sinkhole ponds." These topographically variable wetlands range from seasonally to semipermanently flooded, with water levels maintained by continually perched groundwater or seepage inputs. Overall hydrologic regime is best characterized as seasonally flooded, but two or three of the ponds are almost always flooded year-round. Substrates are generally organic, and the surficial peat in which emergent plants are rooted is extremely acidic. Vegetation varies from entirely herbaceous to a fairly dense shrubland dominated by Cephalanthus occidentalis. Many of the ponds are primarily herbaceous but have outer zones, discrete patches, or islands of shrubs within them. Where present, Cephalanthus occurs in variable abundance, often being limited to marginal zones or specific areas of the pond. In the typical, seasonally flooded ponds, the herb layer is typically dense and dominated by Dulichium arundinaceum. The most frequent and characteristic herbaceous associates are Glyceria acutiflora, Polygonum hydropiperoides, and Proserpinaca palustris. Some ponds have a deep center that is dominated by a zone of Nuphar advena. Several other forbs and graminoids, including Bidens discoidea, Carex canescens ssp. disjuncta, Carex lasiocarpa var. americana, Carex lupulina, Carex stricta, Carex vesicaria, Glyceria septentrionalis, Glyceria canadensis, Glyceria obtusa, Scirpus ancistrochaetus, Schoenoplectus torreyi, Triadenum virginicum, Triadenum fraseri, and Utricularia spp. are inconstant but locally patch-dominant. Semipermanently flooded ponds tend to be floristically depauperate and contain a high proportion of floating or submersed aquatic species, including Torreyochloa pallida, Eleocharis palustris, Glyceria acutiflora, Potamogeton spp., Proserpinaca palustris, and Utricularia spp.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This type was based on quantitative analysis of all montane depression wetlands in Virginia (Fleming and Patterson 2009b). Excellent examples occur in the Maple Flats pond complex in the Shenandoah Valley (Augusta County, Virginia), and the type also appears to be the major type of ridge crest pond in the Ridge and Valley province (Fleming 1998). Other examples include Browns Pond (Warm Springs District, George Washington National Forest), Potts Mountain Pond (New River Ranger District, Jefferson National Forest), and Peters Mountain Pond (James River District, George Washington National Forest).

Similar NVC Types: No Data Available

note: No Data Available