Herbaceous marsh

Herbaceous marsh depressional wetlands are similar in size and shape and occupy the same position on the landscape as cypress domes. The obvious difference is that cypress trees do not dominate marsh depressions. The lack of a cypress tree canopy increases the exposure to the sun so that marsh depressions have a much higher evaporation rate than cypress domes. In general marsh depressions are not as deep and have shorter hydroperiods than cypress domes. Soils are commonly sandy or sandy loam, but organic surfaces are not uncommon in the interiormost portions of the wetland. Marsh depressions generally have vegetative zones that would correlate with the zones described by Stewart and Kantrud in the classic publication Classification of Natural Ponds and Lakes in the Glaciated Prairie Region. The only exception is that many marsh depressional wetlands in Florida do not have a low prairie zone, but transition directly from the upland flatwoods into the wet meadow zone. The first wetland zone adjacent to the upland is the wet meadow zone also referred to as the Hypericum zone (Winchester et. al. 1985) because of the dominance of St. John’s wort in this zone. The wet meadow zone is typically about 30 cm (12 in.) deep. The next zone inward is the shallow marsh or Panicum-Rhynchospora zone. This zone is dominated by maidencane and rush. The shallow marsh is approximately 40 to 50 cm (16 to 20 in.) deep. The deep marsh or mixed emergent zone is the third vegetative zone toward the center of the depressional marsh. This zone is dominated by pickerelweed (Pontederia cordata). The deep marsh zone is about 36 to 50 cm (14 to 20 in.) deep. One or more of the zones described is always found in natural wetlands in the sequence of wet meadow, shallow marsh, and deep marsh. The zones are usually continuous, but in rare cases a zone will only partially extend around the entire wetland. A permanent open-water zone does occur at the innermost portion of some wetlands, but none were sampled as part of this guidebook. However, created or restored wetlands often lack one or more zones or the zones will not form concentric rings.

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Web Date: October 1997
Updated: April 2008