tidal hardwood swamps - Maryland Department of Natural Resources

considered a more northern type usually lacking the previously mentioned southern species. This type is
at the southernmost limit of its distribution in Maryland. Aside from the dominant species, landscape
position and soil composition of this type differed from the Pumpkin ash wetland type by apparent
restriction to the uppermost portions of tidal rivers due to gradual elevation gradients and by soils
containing considerable amounts of clay. The two types determined from the project are the Fraxinus
pennsylvanica – Acer rubrum / Polygonum spp. Tidal Woodland (CEGL006165) and the Fraxinus
profunda – Nyssa biflora / Ilex verticillata / Polygonum arifolium Tidal Woodland (CEGL006287).
The third and final group is seen as resulting from “sea level [rise] and coastal subsidence on the
Delmarva Peninsula” (Tiner 1995). The estuarine forested wetlands dominated by Loblolly pine covers
1,253 acres, the majority of which (806 acres) are found in Dorchester County (McCormick 1982). This
group is defined as being open and savanna like in composition and occurs where “low-lying pine
flatwoods dominated by Loblolly pine are now subject to frequent tidal flooding with salt water” (Tiner
1995). Eventually these hydrologic conditions encourage halophytes to move into the understory,
advancing the salt marsh into the bordering Loblolly pine community. According to Tiner, this is “not a
recent phenomena, since similar observations were reported in the early 1900s (Shreve 1910a)” (Tiner
1995). Unfortunately, while Loblolly pine can withstand some flooding, long-term exposure during the
growing season will eventually stress this species until its eventual demise. Tree mortality rates are
extremely high within this community and dead trunks and stressed crowns are commonly seen within
and in the surrounding areas. The Pinus taeda – Morella cerifera / Spartina patens Tidal Woodland
(CEGL006849) is the single type described from this group.
Conservation Implications
Current conservation norms determine protection priorities based on species level information. Although
the conservation of rare, threatened, and endangered species is a reasonable endpoint, often these
species occur in highly fragmented and human dominated landscapes. These habitat conditions may not
allow the persistence of these species. This type of conservation is substantively attempting to maintain
biodiversity through protecting these occurrences as umbrella endpoints. However, the conservation of
biodiversity may be better served through the protection of rare and/or exemplary common examples of
vegetation communities. Vegetation communities can play a much broader role by linking habitat and
process information to specific species requirements (WPC 1998). Potentially, the protection of
vegetation communities will protect the full range of heterogeneity on the landscape, and thus
biodiversity. Communities can have longer term viability than rare, threatened, and endangered species.
Generally, a large scale stochastic event must occur to alter the structure and composition of vegetation
communities at a site, while smaller scale events could eliminate a species from that same site.
Proper documentation and understanding of the biotic and abiotic factors that contribute to vegetation
communities can lead to predictive ability of where these communities occur on the landscape, what
species can be found within them, and what rarity and condition qualities exist. By creating a
classification of Maryland’s forested tidal wetland communities, this project has assisted in these factors.
The information obtained from this project will be used in planning and regulation by state agencies,
federal agencies, municipalities, land trusts, and conservation groups concerned with protection of
ecological values in the following ways:
1) Inventory information is used directly within the state’s regulatory framework. The Wildlife and
Heritage Service, Maryland Department of Natural Resources, serves as a clearing house of
information on the status, location, and distribution of rare plant and animal species and
exemplary natural communities in the state. The Wildlife and Heritage Service administers the
state’s Threatened and Endangered Species Act, which requires the compliance of state
agencies, private land developers in the protection of threatened and endangered species with
the state via permitting for proposed activities affecting said species.
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