Ponded Floodplain Marsh

Description

The reference plant community is categorized as a marsh dominated by hydrophytic vegetation. The three community phases within the reference state are dependent on seasonal flooding and precipitation as well as an average fire return interval of three years. The amount and duration of ponded water alters species composition, cover, and extent, while regular fire intervals and long duration ponding keep woody species from encroaching. Animal disturbances from beaver and muskrats have more localized impacts in the reference phases, but do contribute to overall species composition, diversity, cover, and productivity.

Dominant plant species

1. river bulrush (Bolboschoenus fluviatilis), grass

2. broadleaf arrowhead (Sagittaria latifolia), grass

Submodel

Description

Fire suppression can transition the reference herbaceous marsh community into a woody-dominated marsh. Historically, hot replacement fires occurred on a two to five year cycle and helped to reduce woody encroachment and thatch build-up (LANDFIRE 2009). Over the past 150 years, however, fire suppression policies have allowed shrubs and trees to succeed into areas where they did not historically occur.

Dominant plant species

1. common buttonbush (Cephalanthus occidentalis), shrub

2. water knotweed (Polygonum amphibium), grass

Submodel

Description

Agricultural drainage, stream channelization, and levee construction in hydrologically-connected waters has drastically changed the natural hydrologic cycle of Ponded Floodplain Marshes. Reduced backwater flooding and excessive siltation from upland erosion has caused accelerated soil dehydration. This has resulted in a type conversion from the species-rich herbaceous marsh to a simplified, woody-dominated state (Nelson 2010; Steinauer and Rolfsmeier 2010). In addition, the change in the hydrologic cycle (coupled with agricultural runoff) has resulted in a serious invasion of exotic species (Green and Galatowitsch 2002; Kercher et al. 2007; Nelson 2010).

Dominant plant species

1. silver maple (Acer saccharinum), tree

2. black willow (Salix nigra), shrub

3. narrowleaf cattail (Typha angustifolia), grass

Submodel

Description

The Midwest is well-known for its highly-productive agricultural soils, and as a result, much of the MLRA has been converted to cropland, including portions of this ecological site (USGS 1999). Agricultural tile drains and surface drainage systems used to lower the water table and continuous use of tillage, row-crop planting, and chemicals (i.e., herbicides, fertilizers, etc.) have effectively eliminated the reference community and many of its natural ecological functions in favor of crop production. Corn (Zea mays L.) and soybeans (Glycine max (L.) Merr.) are the dominant crops for the site. These areas are likely to remain in crop production for the foreseeable future.

Submodel