National Park Service

Appalachian Highlands Network (APHN)

Cobble Bar Monitoring

Field crew sampling a cobble bar habitat [photo by Nora Murdock]
Field crew sampling a cobble bar habitat [photo by Nora Murdock]

Resource Brief: Cobble Bar Monitoring in APHN

Cobble Bar Monitoring Protocol

There are currently no other documents or reports pertaining to this topic.

For more information contact: Evan Raskin

Affected Parks

  • Big South Fork National River & Recreation Area (BISO)
  • Obed Wild and Scenic River (OBRI)

Importance / Issues

Cumberlandian cobble bars (also called "river scour prairies") are unique plant communities endemic to the Cumberland Plateau of Tennessee and Kentucky. Ranked as Globally Imperilled (G2) by The Nature Conservancy and vulnerable to extinction throughout their range, they exist on open, flood-scoured exposures of bedrock, cobble or gravel along large rivers.

Typically thick with grasses and flowering herbs, these river scour prairies share many characteristics with the tallgrass prairies of the American Midwest. Whereas fire is the driving force sustaining Midwestern prairies, water is the ecological driver in the bottoms of the deep river gorges of the Cumberland Plateau. Raging floods wash over these habitats on multiple occasions each year, scouring out species that are not adapted to disturbance, including most trees and other woody species. Grasses, herbs, and some low shrubs thrive under these punishing conditions. Several extremely rare plants, including some that grow nowhere else in the world, flourish in these unique riparian prairies. Among these are two Federally-listed species - Cumberland rosemary (Conradina verticillata) and Virginia spiraea (Spiraea virginiana), as well as several dozen other globally or regionally rare plants.

Monitoring Objectives

The goals of this long-term monitoring effort are to determine whether cobblebar communities are being negatively impacted by changes in natural flood cycles or degradation of water quality. If normal flood cycles are disrupted by upstream impoundments or water withdrawal, these open, grassy communities could vanish, replaced by woody species—including non-natives—that would not ordinarily be able to survive here.

Specific objectives are to document:

  1. Long-term trends in community structure (e.g., cover, density by height class of woody species, cover and density of grasses and herbs).
  2. Long-term trends in abundance and size class distribution of selected rare, threatened and endangered plant species on the cobble bars.
  3. Long-term trends in cobble bar substrate composition (sand, gravel, cobble, boulder, coal sediment).
  4. Presence and abundance, by species, of invasive exotics.

Management Applications

Information gathered from this monitoring, in concert with water quality monitoring, will provide park managers with a baseline against which to assess future changes in this imperiled community and its rare inhabitants, detrimental resource changes associated with water quality degradation and disruptions of natural hydrological cycles, as well as early detection of invasive exotic species.

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Last Updated: October 05, 2017 Contact Webmaster