Physiognomy and Structure: No Data Available

Floristics: This community is a broadleaf deciduous floodplain forest which exhibits high canopy diversity and good herbaceous diversity (although lower herbaceous diversity than mesic floodplain forest). Ulmus americana was once the most prominent member of this forest, but Dutch elm disease (Ceratostomella ulmi) and logging have eliminated many of the largest mature Ulmus spp. from most of the species natural range (Collingwood and Brush 1984). Fraxinus pennsylvanica dominates on moist flats and shallow sloughs, while Celtis laevigata is most prevalent on new land or front sites. Other species commonly encountered include Carya aquatica, Quercus lyrata, Liquidambar styraciflua, and Acer negundo. The subcanopy is often dense and dominated by Fraxinus pennsylvanica which sprouts prolifically. Fraxinus pennsylvanica, however, is considered a pioneer species and does not maintain its canopy position under intense shading found in later successional stages (Voigt and Mohlenbrock 1964). Shrubs typical of this forest include Cornus drummondii, Ilex decidua, and Crataegus spp. The herbaceous layer is dense and diverse, dominated by Galium spp., Viola spp., Carex spp., Leersia spp., Boehmeria cylindrica, Laportea canadensis, Pilea pumila, Impatiens capensis (= Impatiens biflora), and Impatiens pallida. Vines most often encountered include Toxicodendron radicans, Campsis radicans, and Parthenocissus quinquefolia (TNC 1995a).

Species variability within and among occurrences of this community is great and directly related to the level of saturation of the substrate. Alluvial deposition varies and slight ridges may favor sugarberry, while depressions will favor green ash. Species variability and composition within this community are considerable as a result of a mosaic of moisture conditions controlled by seasonal flooding and local topography. In the northern part of the range (north-central Oklahoma, northern Arkansas, Missouri, Tennessee, Kentucky, southern Illinois, southeastern Indiana), this community coincides with the distribution of Celtis occidentalis. In this section Celtis occidentalis is often a dominant in the canopy-subcanopy. In Louisiana, Mississippi, Alabama, Arkansas, and southwestern Missouri, Quercus texana is a major associate in this type. Celtis laevigata is especially abundant on river front and disturbed sites. Fraxinus pennsylvanica is relatively more abundant on saturated flats or shallow sloughs. Berchemia scandens is common in this community northward through southeastern Virginia and Tennessee. Areas that have been cleared or logged in the past may have locally abundant disturbance species such as Acer rubrum, Pinus taeda, Liquidambar styraciflua, or Platanus occidentalis.

Dynamics:  Frequent or prolonged ponding due to excessive rainfall or beaver activity results in considerable variations in vegetative structure and composition, often causing high tree mortality. Flooding occurs during the winter and spring and often extends into the growing season. Although this community can be early-successional, occurring on river fronts and other recently disturbed areas, this is a generally long-lived type (Eyre 1980, Diamond 1993). This community is usually located in transitional areas between Quercus michauxii - Quercus pagoda floodplain forests and Quercus lyrata - Quercus phellos bottomland forests.