Wetlands
Wetland Functions and Values
The physical, chemical, and biological properties of the Commonwealth’s wetlands work in concert to perform “wetland functions”. Wetland functions may include: storage of water, ground water recharge, sediment trapping, transformation of nutrients, and wildlife habitat. Wetlands are some of the most productive habitats on earth, providing nursery grounds for shellfish, fish and other vertebrate wildlife.
The benefits society derives from wetlands functions are often referred to as wetland values. Some widely applicable wetland values include: flood attenuation, water purification, and wildlife habitat. When wetlands store water along a larger waterbody, they often serve to attenuate periodic flood waters. The process of storing water also slows water to trap sediment and pollutants caused by over land or upstream water flow. As wildlife habitat, wetlands provide hunting and fishing opportunities.
Virginia Wetland Diversity, Virginia Landscape Diversity
An exceptional diversity of wetlands is found across the Virginia landscape. Swamps, tidal marshes, wet meadows, bogs, pocosins and sinkhole wetlands are some of the many types of wetlands found here. The Commonwealth has
five physiographic regions each with specific elevation, geologic, and hydrologic influences. Extending from the eastern coast to the western state-line, and exhibiting increasing elevation, Virginia’s physiographic regions are the Coastal Plan, Piedmont, Blue Ridge Mountains, Valley and Ridge, and Appalachian Plateau. In the Coastal Plain, wetlands are predominantly tidal marshes and tidal forests. In the Piedmont region, isolated or stream-side freshwater forests are the dominant wetland type. In the Blue Ridge Mountains, Valley and Ridge, and Appalachian Plateau; most wetland forests or marshes are associated with streams.
Virginia’s landscape also is commonly categorized by seven
ecoregions. According to the U.S. EPA, “Ecoregions reflect areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources, they are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components
”(
Woods et al. 2003). The
seven ecoregions in Virginia include:Piedmont, Middle Atlantic Coastal Plan, Northern Piedmont, Southeastern Plains, Blue Ridge, Ridge and Valley, and Central Appalachian. Each ecoregion contains a characteristic, geographically distinct assemblage of natural communities and species. The biodiversity of flora, fauna, and ecosystems that characterize an ecoregion tend to be distinct from that of other ecoregions.
Lesser Known Wetlands of Virginia
Sinkhole or Karst Depressional Wetlands. In Virginia, the karst, or swiss cheese topography of eastern Augusta, Rockingham, and PageCounties in the central Shenandoah Valley exhibit ancient sinkhole wetlands. Sinkhole wetlands are a type of
Montane Depression Wetland. Because they are largely impermeable, many sinkhole wetlands store rainwater long into the drier seasons. Karst regions contain caves and other openings formed from the dissolution of rock such as limestone. They provide unique wildlife habitat and are often linked to aquifers capable of holding large volumes of groundwater.
Vernal Pools. As the name suggests vernal pools are areas that are accumulate water during the spring months. They provide safe breeding habitats for frogs and salamanders. Because they become completely dry in the fall, they lack predators such as fish and bullfrogs. During drier seasons, vernal pools may be difficult to identify as a wetlands making them very vulnerable to development. Vernal pools are found throughout the state in forests and meadows.
Coastal Plain Depression Wetlands are one type of vernal pool described by the
The Natural Communities of Virginia.
Pocosins. Found in the southeastern coastal plain, pocosins typically sit on hillside plateaus and accumulate acidic peat like northern bogs. Pocosins experience occasional fires and therefore exhibit a diversity of shrubby evergreens. Like so many wetlands in the Coastal Plain, pocosins serve as important migratory and over-wintering habitat for birds. Pond Pine Woodlands and Pocosins, and Streamhead Pocosins are differentiated in
The Natural Communities of VirginiaFloristic Quality Assessment Index (FQAI)
As part of the scope of work for the Wetland Monitoring and Assessment grant, DEQ worked with botanical experts and wetland scientists from various regions of Virginia to develop a Floristic Quality Assessment Index (FQAI) to be used as a qualitative indicator of a wetland’s relative condition. The FQAI has been shown in other states to be a reliable means of assessing wetland quality with minimal data collection. Development of a FQAI specific to Virginia involves determining Coefficient of Conservatism values (C-values) for vascular plants frequently encountered in tidal and nontidal wetlands in Virginia. The assignment of C-values is the first phase of developing a FQAI to help assess relative wetland function and quality as part of DEQ’s on-going wetland monitoring and assessment efforts.
Using the Calculator
Enter the plants you have found by genus and species using the FQAI Calculator’s drop down boxes. (Note: Upon selecting another genus your previous entry will be alphabetized in the list.) The calculator will perform the computation to determine the Floristic Quality Assessment Index as defined by an committee of expert botanists and wetland scientist. A committee of four (4) botanical experts (chaired by VDEQ staff) determined, through consensus, a coefficient of conservatism (C) for each plant species on the list. The C-value will range from 0 (most likely to occur in disturbed landscapes or a non-native species) to 10 (most likely to occur in undisturbed landscapes). Intermediate integers will be assigned based upon the species tolerance to disturbance.
Survey Notes
It is recommended that your survey area be at least 100 meters square for the most valid results, and it is important to identify every plant in that area. The season in which you perform your survey may affect your results, so it would be interesting to revisit the same sites in different seasons. Mid July is recommended for wetland and riparian sites as sedge and grass identification to species is important.
Use Calculator