Chapter 4 Habitats
4.3.5 Floodplains – Brownwater Systems 4.3.5.1 Ecosystem Description
This ecosystem group includes the vegetated communities that occur on brownwater floodplains. In contrast to blackwater rivers, they carry heavy loads of mineral sediment, particularly clay and silt. The water is generally near neutral pH and high in nutrients. The deposition of sediment in the floodplain provides a periodic nutrient input that keeps the soils rich. Depositional topographic features such as natural levees, point bars, ridge-and-swale systems, and sloughs are well developed, with their size depending on the size of the river.
Communities that occur in blackwater floodplains include the following themes ( Schafale 2024) .
• Brownwater bottomland hardwoods (high, low, swamp transition subtypes) • Brownwater levee forest (bar, high levee, low levee, and medium levee subtypes) • Coastal plain semipermanent impoundment (cypress-gum, open water, Sandhills marsh, Sandhills mire, and typic marsh subtypes) • Cypress-gum swamp (brownwater and intermediate subtypes) • Oxbow lake • Sand and mud bar (brownwater and narrowleaf pond-lily subtypes) • Sandhill streamhead swamp 4.3.5.2 Location of Habitat Brownwater rivers originate in the Mountains or Piedmont and flow eastward into the Coastal Plain ecoregion. Though brownwater floodplain forests of various conditions and sizes can be found throughout the Coastal Plain ecoregion, the number of them is limited to the Roanoke, Tar/Pamlico, Neuse, and Cape Fear rivers. The condition of Coastal Plain floodplain forests of all types has been greatly reduced in recent years throughout North Carolina and the entire Southeast (Weller and Stegman 1977; Schafale and Weakley 1990, Schafale 2024) by a variety of anthropogenic factors. 4.3.5.3 Problems Affecting Habitats Chapter 5 Threats provides more information about 11 categories of threats most likely to impact North Carolina’s wildlife and natural communities. The list of threats is based on definitions and classifications published by Salafsky et al. (2008, 2024) . The following information focuses on current and anticipated threats for this habitat. Flooding . Factors that impact these systems include flooding regime patterns that have been changed by dams and other development, habitat fragmentation, changes in water chemistry and organic matter loads, increased nitrogen from agricultural and development-related runoff, exotic species and high-grading of stands and logging that reduces wide buffers. All these factors individually or interactively produce abrupt or gradual changes in floodplain plant and wildlife communities. In particular, the sediment load in many brownwater rivers is now a
4 - 151
2025 NC Wildlife Action Plan
Made with FlippingBook Ebook Creator