Pocosin

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Pocosin is a term for a type of palustrine wetland[1] with deep, acidic, sandy, peat soils. Groundwater saturates the soil except during brief seasonal dry spells and during prolonged droughts. Pocosin soils are nutrient deficient (oligotrophic), especially in phosphorus.[2]

Pocosins occur in the Atlantic coastal plain of North America, spanning from southeastern Virginia, through North Carolina, and into South Carolina. However, the majority of pocosins are found in North Carolina.[3] They occupy poorly drained higher ground between streams and floodplains. Seeps cause the inundation. There are often perched water tables underlying pocosins.

Shrub vegetation is common. Pocosins are sometimes called shrub bogs. Pond pines (Pinus serotina) dominate pocosin forests, but loblolly pine (Pinus taeda) and longleaf pine (Pinus palustris) are also associated with pocosins. Additionally, pocosins are home to rare and threatened plant species including Venus flytrap (Dionaea muscipula) and sweet pitcher plant (Sarracenia rubra).[2]

A distinction is sometimes made between short pocosins, which have shorter trees (less than 20 feet (6.1 m)), deeper peat, and fewer soil nutrients, and tall pocosins, which have taller trees (greater than 20 feet (6.1 m)), shallow peat, and more soil nutrient.[2] Where soil saturation is less frequent and peat depths shallower, pocosins transition into pine flatwoods. A loose definition of "pocosin" can include all shrub and forest bogs, as well as stands of Atlantic White Cypress (Chamaecyparis thyoides) and loblolly pine on the Atlantic coastal plain. A stricter definition (promulgated by A. W. Kuchler) restricts pocosins to shrubby "short pocosins" and pond pine-forested "tall pocosins".[2]

Pocosins are formed from thousands of years of organic matter build up that resembles black muck. The accumulation of this material causes the area to be highly acidic and nutrient deficient. The thickness of the organic buildup varies depending on where you’re at. Near the edges it’s only several inches thick but as you reach the center it can be up to several feet thick. The vegetation also varies throughout. On the edges you have more pond pine, lots of titi, Zenobia (a shrub that is unique to pocosins), and lots of greenbrier vines.[4] Closer to the center you find lots of thin trees that have been stunted, but less and less shrubs and vines.[5]

Pocosins are very important for birds living in cold climates during the winter months due to the abundance of various types of berries that are available.[5]

Pocosin ecosystems are fire-adapted (pyrophytic). Pond pines exhibit serotiny, such that wildfire can create a pond pine seedbed in the soil. Wildfires in pocosins tend to be intense, sometimes burning deep into the peat, resulting in small lakes and ponds.

Wildfires occurring about once a decade tend to cause pond pines to dominate over other trees, and cane (Arundinaria) rather than shrubs to dominate the understory. More frequent fires result in a pyrophytic shrub understory. Annual fires prevent shrub growth and thin the pond pine forest cover, creating a flooded savanna with grass, sedge, and herb groundcover.

The word pocosin comes from an Eastern Algonquian word meaning "swamp-on-a-hill",[1] however, a more accurate description of a pocosin would be a “raised bog”.[4] The city of Poquoson, Virginia, located in the coastal plain of Virginia (see Tidewater region of Virginia), derives its name from this geographic feature.

Notes[edit]

  1. ^ a b Curtis J. Richardson (1983). "Pocosins: Vanishing Wastelands or Valuable Wetlands?". BioScience 33 (10): 626–633. JSTOR 1309491. 
  2. ^ a b c d Snyder, S. A. (1993). Pocosin. In: Fire Effects Information System, (Online). Fire Sciences Laboratory, United States Forest Service. Retrieved 2011-02-16.
  3. ^ Rapid Assessment Reference Condition Model: Potential Natural Vegetation Group: Pocosin. n.p. (2005). PDF. 9 Oct. 2013.
  4. ^ a b Pocosin Wilderness. Wilderness, n.p. n.d. Web. 9 Oct. 2013.
  5. ^ a b Mid-Atlantic Coastal Plain. n.p. n.d. PDF. 9 Oct. 2013.

References[edit]