Riparian classification is a process for grouping and describing riparian communities with similar floristics, environmental characteristics, and management potentials. In the US Forest Service, teams with expertise in plant taxonomy and ecology, soils, water relationships, stream and watershed function, and geology and landforms conduct riparian classification work. Riparian classification results in a written guide to riparian plant communities, including keys, descriptions, photos, and management characteristic.
In the Pacific Southwest Region, both riparian and transitional sites are classified. These include streambanks, active channel shelves, floodplains, overflow channels, as well as the sub-surface irrigated meadow and terrace sites that lie between the wettest areas and the true uplands.
Riparian classification begins by sampling within stratified areas of similar vegetation, soils, stream type, geology, and landform. These data are analyzed, enabling the ecologist to classify the sites into similar groupings. Because disturbed, early seral ecosystems are common in riparian areas, both existing and potential plant communities are typically described.
The information on community types and seral pathways provided by riparian classification enables resource managers to be very specific when developing management prescriptions for other resources (e.g. livestock, timber, fisheries) within a riparian system. The following examples illustrate the application of riparian classification to management decisions for riparian systems:
Example 1: A management plan is being developed for a site with the following existing conditions: a 2 percent gradient, cobble fragment, perennial stream channel with 35 percent hardwood cover. Riparian classification identifies a site potential for 85 percent hardwood cover in this stream type and land form. The land managers want a mix of site characteristics that provide streambank protection and shading, thermal cover, livestock forage, and species diversity. Classification aids in the identification of the optimal seral stage-one with 60% hardwood cover-that provides a better mix of desired characteristics than that which occurs in the existing or the potential plant community. Managers can now prescribe specific management to develop and maintain the desired plant community.
Example 2: A restoration plan is being developed for a downcut meadow channel with a high width-to-depth ratio. Vegetation is an array of grazing-disclimax communities such as mountain silver sagebrush, Kentucky bluegrass, forbs, and Douglas sedge. Water temperatures and sediment levels are high, and the stream has no pools. Riparian classification identifies this site as disturbed and early seral. Short-term potential (10-20 years) exists for development of willow, Nebraska sedge, and bulrush communities. Longer-term potential (50-100 years) is for formation of a narrow, deep, perennial, meandering sedge-dominated channel with undercut banks, low stream temperatures, and beaked and wooly sedge communities. The classification identifies seral pathways and key management species, as well as specific actions to speed up succession, including grazing management, species-specific vegetation plantings, and appropriateness of instream structures. In this example, managers use the classification to select specific short-term and long-term actions that will advance the site towards desired condition-in this case, site potential.
Riparian classifications have been published for National Forest areas of Eastern Oregon, Nevada, Utah, and Idaho. Classification efforts are currently underway in the Pacific Southwest Region on the Inyo, Modoc, Lassen, Six Rivers, and Plumas National Forests.
For more information, contact Terry Hicks, Ecologist, Inyo National Forest (619-873-5841), or Sydney Smith, Ecologist, Modoc National Forest (916-233-5811)
