State of the Wetlands

The purpose of the State of the Wetlands Report is to paint the big picture of wetlands in North and South Carolina. The report establishes a baseline for measuring future trends in wetlands in the Carolinas. We strive to provide answers to following questions:

  • What is the state of our wetlands?
  • How many wetlands do we have?
  • What are the most important wetlands?

Wetland protection is becoming more and more important as both State and Federal regulations are being eroded by changes in WOTUS (at the federal level) and shifts in regulatory priorities in both state legislatures. Fortunately, Carolina’s citizens and conservation and environmental organizations are active protectors of wetlands and their vital position where the “water and the land meet”.

Many creatures depend on wetlands for habitat, food sources, and enjoyment.

Wetlands are special ecosystems

Carolina wetlands are diverse habitats found across the coastal plain, piedmont, and mountain regions of North and South Carolina. Wetlands are transitional areas where land meets water near streams, rivers, lakes, and estuaries, or in low-lying flat areas or natural depressions in the landscape. The depth and duration of water logging combined with landscape position are key factors in determining when wetland soils develop and plant species inhabit them to create a wetland community.

In North and South Carolina, the National Wetlands Inventory (NWI) estimates there are 8.1 million acres (over 12,600 square miles) of wetlands, with 4.2 million acres in North Carolina and 3.8 million acres in South Carolina. This means that wetlands account for about 14% of the land area in North Carolina and almost 20% of South Carolina!

Most of these wetlands are found in the coastal plain, with only 4.8% in the piedmont and less than 0.2% in the mountains. That means these wetlands are even more important because they are critical hydrologic components of the watershed and provide habitats for threatened and endangered species. Click here to view a map of all the wetlands in the Carolinas.

In terms of vegetation type, Carolina wetlands are mostly freshwater forested or shrub-covered (87%) with only 4% as freshwater emergent/herbaceous marsh vegetation and 9% estuarine/marine marsh vegetation (Exhibit 2).

 Exhibit 2. U.S. Fish and Wildlife Service National Wetland Inventory for North and South Carolina

National Wetland Inventory

Acres

Sq. Miles

%

Estuarine and Marine Wetland

708,635

10,964

8.8%

Freshwater Emergent Wetland

341,030

533

4.2%

Freshwater Forested/Shrub Wetland

7,016,716

5,016

87%

Other

549

1

 

Total

8,066,929

12,605

100%

In 2011, the U.S. Environmental Protection Agency (EPA) embarked on the first national scale evaluation of the ecological condition of U.S. wetlands called the National Wetlands Condition Assessment (NWCA). Close to 1,000 wetland sites were randomly chosen across the  U.S. Forty-seven (47) sites in North Carolina and 40 sites in South Carolina were surveyed which is reflective of the fact that North and South Carolina have the third and fourth highest amount of wetland lands in the conterminous U.S. behind Louisiana and Florida. 

The condition of wetlands in North and South Carolina was similar with the majority of the wetlands sampled in good condition.

North Carolina 

  • 57% rated good 
  • 28% rated fair 
  • 15% rated poor

South Carolina

  • 55% rated good
  • 25% rated fair 
  • 20% rated poor

Source: US EPA, National Wetland Condition Assessment

Based on U.S. Environmental Protection Agency (EPA)’s 2011 National Wetlands Condition Assessment (NWCA), the leading stressors in wetlands were caused by physical disturbances to wetlands and their surrounding habitat. The leading stressors for our wetlands are as follows:

North Carolina

  • 26% Ditching 
  • 9%    Non-native vegetation
  • 6%    Compacted soils 
  • 4%    Vegetation loss or removal  

South Carolina

  • 23% Vegetation loss or removal 
  • 18% Ditching
  • 10% Compacted soils
  • 3 %  Non-native vegetation

Source: US EPA, National Wetland Condition Assessment

Carolina wetlands provide a host of valuable ecosystem services to human and other residents. Most (over 85%) of Carolina wetlands are wetland forests and a recent study by the Dogwood Alliance conducted a state-by-state valuation of the services that wetland forests provide in the southeast. Exhibit 3 totals and presents the ecosystem services provided by forested wetlands in the Carolinas. In total, the study estimates that wetlands provide almost $70 billion in ecosystem services to North and South Carolina citizens.

Exhibit 3. Ecosystem Services Provided by Forested Carolina Wetlands

Ecosystem Service

Value

Protection from extreme events

$20 B.

Aesthetics, recreation, tourism     

$16 B.

Water filtration/treatment             

$15 B.

Food/pollination

$ 9.5 B.

Regulating services

$ 5.9 B.

Total

$67 B.

Examples of the ecosystem services performed by Carolina wetlands include:

  • Protection from extreme events. Wetlands help shelter and protect coastlines and inland areas from damage from storm surge and help mitigate flooding from excess rainfall.
  • Water filtration and treatment. Wetlands can improve water quality by fixing nitrogen, retaining phosphorous, and filtering out sediment and toxic metals.  
  • Regulating services. Wetlands regulate water flow and landscape hydrology by contributing dynamic water storage during high flows and limiting peak flow frequency, magnitude, and duration. Wetlands are also central to carbon cycling in the environment, serving as a primary sink for sequestering carbon across the landscape.
  • Food/Pollination. As wildlife refuges and critical supporting habitats for fish and shellfish, wetlands support recreational hunting and commercial and recreational fishing in the Carolinas.
  • Aesthetics, Recreation, and Tourism. Wetlands are beautiful and offer great places to hike and paddle. Examples of great wetlands to visit are our Wetland Treasures of the Carolinas

As the Carolinas get warmer and wetter, wetlands provide numerous benefits and services related to mitigating negative impacts of a changing climate.

  • Wetlands sequester carbon – in trees and shrubs, and in the peat that accumulates in them
  • Wetland forests cool the landscape and improve regional microclimates
  • Wetlands protect against storm damage from increasing winds and storm surge
  • Wetlands mitigate flooding and regulate flow as rainfall increases & sea levels rise

Wetlands also are affected by climate change. For example

  • Coastal freshwater wetlands are vulnerable to sea level rise and stronger, slower, and more frequent storms.
  • Floods can wash out sequestered carbon
  • Rising temperatures can change species compositions by eliminating cool-weather species.
  • Drought can change wetlands to dryland and eliminate the hydroperiods critical to wetland health
  • Change in temperature and precipitation can favor invasive species

Active research across the Carolinas is ongoing on how climate change impacts wetlands and how wetlands can impact climate change. 

Carbon Sequestration

Wetlands play a significant role in climate change mitigation by acting as carbon sinks. Click here to read more.

Pocosin Restoration

Restoration efforts aim to restore the natural hydrology of the drained pocosins to promote carbon storage. Click here to read more.

Acreman, M., and J. Holden. 2013. How wetlands affect floods. Wetlands 33(5): 773-786. October. https://link.springer.com/article/10.1007/s13157-013-0473-2

Bridgham, S.D., J.P. Megonigal, J.K. Keller, N.B. Bliss, and C. Trettin. 2006. The carbon balance of North American wetlands. Wetlands 26(4): 889-916. December. https://link.springer.com/article/10.1672%2F0277-5212%282006%2926%5B889%3ATCBONA%5D2.0.CO%3B2#citeas

Capps, K.A., R. Rancatti, N. Tomczyk, T.B. Parr, A.J.K. Calhoun, and M. Hunter. 2014. Biogeochemical hotspots in forested landscapes: the role of vernal pools in denitrification and organic matter processing. Wetlands 17(8): 1455-1468. December. https://link.springer.com/article/10.1007/s10021-014-9807-z.  

Cohen et al. 2016. Do geographically isolated wetlands influence landscape functions? PNAS 113(8): 1978-1986. https://www.pnas.org/content/113/8/1978

Craft, C.B., and W.P. Casey. 2000. Sediment and nutrient accumulation in floodplain and depressional freshwater wetlands of Georgia, USA. Wetlands 20(2): 323-332. June. https://link.springer.com/article/10.1672/0277-5212(2000)020[0323:SANAIF]2.0.CO;2    

Dahl, T.E., and S.M. Stedman. 2013. Status and trends of wetlands in the coastal watersheds of the Conterminous United States 2004 to 2009. U.S. Department of the Interior, Fish and Wildlife Service and National Oceanic and Atmospheric Administration, National Marine Fisheries Service (46 p.). https://www.fws.gov/wetlands/documents/Status-and-Trends-of-Wetlands-In-the-Coastal-Watersheds-of-the-Conterminous-US-2004-to-2009.pdf

Gambrell, R.P. 1999. Trace and toxic metals in wetlands – a review. Journal of Environmental Quality 23(5):883-891. September. https://www.researchgate.net/publication/240784057_Trace_and_Toxic_Metals_in_Wetlands_-_A_Review

Golden, H.E., H.A. Sander, C.R. Lane, C. Zhao, K. Price, E. D’Amico, J.R. Christensen. 2016. Relative effects of geographically isolated wetlands on streamflow: a watershed‐scale analysis. Ecohydrology 9:21-38. March. https://onlinelibrary.wiley.com/doi/full/10.1002/eco.1608  

Gordon, D.H., B.T. Gray, R.D. Perry, M.B. Prevost, T.H. Strange, and R.K. Williams. 1989. South Atlantic coastal wetlands. p. 57-92 in: Smith, L.M, R.L. Pederson, and R.M. Kaminski. Habitat management for migrating and wintering waterfowl in North America. Texas Tech University Press. Lubbock, TX.

McLaughlin, D.L., D.A. Kaplan, and M.J. Cohen. 2014. A significant nexus: Geographically isolated wetlands influence landscape hydrology. Water Resources Research 50: 7153-7166. September. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013WR015002

Min, J-H., D.B. Perkins, and J.W. Jawitz. 2010. Wetland-groundwater interactions in subtropical depressional wetlands. Wetlands 30(5): 997-1006. October.  https://link.springer.com/article/10.1007/s13157-010-0043-9

Morris, J.T., J. Edwards, S. Crooks, and E. Reyes. 2012. Assessment of Carbon Sequestration Potential in Coastal Wetlands. In: Lal, R., K. Lorenz, R.F. Hüttl, B.U. Schneider, and J. von Braun (Eds.).  Recarbonization of the Biosphere – Ecosystems and the Global Carbon Cycle. Springer Netherlands.  https://link.springer.com/chapter/10.1007/978-94-007-4159-1_24

Reddy, K.R., R.H. Kadlec, E. Flaig, and P.M. Gale. 1999. Phosphorus retention in streams and wetlands: A review. Critical Reviews in Environmental Science and Technology 29(1): 83-146. https://www.tandfonline.com/doi/abs/10.1080/10643389991259182

U.S. EPA (Environmental Protection Agency). 2016. National Wetland Condition Assessment 2011: A Collaborative Survey of the Nation’s Wetlands. EPA-843-R-15-005. Office of Wetlands, Oceans and Watersheds, Office of Research and Development. Washington, DC. May. https://www.epa.gov/sites/production/files/2016-05/documents/nwca_2011_public_report_20160510.pdf

USGS (U.S. Geological Survey). 1996. National Water Summary-Wetland Resources. Water-Supply Paper 2425. USGS. Reston, VA. https://pubs.er.usgs.gov/publication/wsp2425.

Whigham, D.F., C. Chitterling, B. Palme. 1988. Impacts of freshwater wetlands on water quality: A landscape perspective. Environmental Management 12(5): 663-671. September. https://link.springer.com/article/10.1007/BF01867544

Let us know if have suggestions and/or questions about the State of Wetlands in the Carolinas. Contact the Science Committee co-chairs: at info@carolinawetlands.org.