tidal hardwood swamps - Maryland Department of Natural Resources

Pocomoke River Worcester and Somerset Counties, Maryland
USGS QUADS
Snow Hill, MD
Pocomoke City, MD
PRIMARY REASON FOR SELECTION
Pocomoke River contains high quality occurrences and one of Maryland’s best examples of the
Taxodium distichum - Nyssa biflora / Bignonia capreolata tidal forest (CEGL006059).
The term high quality occurrence is defined by four factors: 1) the site includes a very
representative example of the vegetation type as defined in the Maryland Vegetation
Classification, 2) the occurrence is in good to excellent condition -- the habitat supporting this
community type is less degraded than other known occurrences, 3) the occurrence has a good to
excellent viability -- long term prospects for the continued existence of this occurrence are high,
and 4) the occurrence has good to excellent defensibility -- this occurrence can be protected from
extrinsic human factors.
SITE DESCRIPTION
Pocomoke River contains an expansive occurrence (>40 hectares) of Taxodium distichum -
Nyssa biflora / Bignonia capreolata tidal forest community along its main channel and tributaries.
This site is located from the mouth of Nassawango Creek to just north of Milburn Landing. Mean
salinity at time of study was 0.0 ppt. The Taxodium distichum - Nyssa biflora / Bignonia
capreolata tidal forest community occurs along much of the Pocomoke River. The total length of
this occurrence spans from Porter’s Crossing Bridge southwest to Hickory Point Cypress Swamp,
including tributaries for approximately 42 kilometers. This community type is bordered by a
mixture of tidal and non-tidal communities that includes a variety of emergent vegetation types,
tidal shrublands, tidal woodlands, Chamaecyparis thyoides swamps, and dry, upland sand ridges
dominated by pines and oaks. The microtopography within this community is composed of
pronounced hummock-and-hollow formations with high concentrations of root material,
woody/organic debris and cypress knees mixed throughout the mucky substrate. Canopy cover
is closed due to the crown density of Taxodium distichum, however both shrub and herb layers
are exceptionally diverse.
Emergent vegetation throughout the freshwater portion of Pocomoke River includes narrow zones
of Nuphar lutea ssp. advena and scattered patches of dense Zizania aquatica. Small, but dense
tidal shrubland communities dominated by Alnus maritima are scattered throughout the lower
portion of Nassawango Creek. While these shrublands are generally found along the tidal
forested community edge, Alnus maritima also has a tendency to form small dense island-like
pockets surrounded by either open water or dense emergent vegetation such as Nuphar lutea
ssp. advena.
Dry, upland forests dominated by oaks and pine are found throughout the region and border most
of the lowlands adjacent to Pocomoke River, including the tidal forests. The width of the
transition zone between the pine forests and the tidal forests can vary from narrow to broad,
depending on the rate of increase in elevation between the lowland and the upland. The
transition zone may include tree species such as Chamaecyparis thyoides, Pinus taeda,
Juniperus virginiana, Quercus spp., Liriodendron tulipifera and Betula nigra and typically includes
a dense evergreen shrub layer composed of a few species that include Kalmia latifolia, Ilex glabra
and Morella cerifera (=Myrica cerifera) (Beaven & Oosting 1939).
Land-use in the surrounding uplands is primarily agricultural; the extensive tidal and upland
forests serve as buffers between farmland and the Pocomoke River along most of its length.
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