What is a Riparian Area?
Riparian zones or areas have been defined in several ways, but they are essentially the narrow strips of land that border creeks, rivers or other bodies of water. Because of their proximity to water, plant species and topography of riparian zones differ considerably from those of adjacent uplands. Although riparian areas may occupy only a small percentage of the area of a watershed, they represent an extremely important component of the overall landscape. This is especially true for arid-land watersheds, such as those in Eastern Oregon.
Functions of a Healthy Riparian System:
- Sediment filtering
- Bank stablilization
- Water storage and release
- Aquifer recharge
A healthy, functioning riparian area and associated uplands dramatically increase benefits such as fish and wildlife habitat, erosion control, forage, late season streamflow, and water quality. Management decisions must be designed with these processes in mind.
An unhealthy system would have some or all these characteristics:
- Low water table and decreased storage capacity
- Low forage production
- Little shade-Warm water
- Poor fish habitat-Poor water quality
- Low wildlife habitat diversity
- Little vegetation & roots to help protect and stabilize banks
- Reduced late summer stream flows
A healthy system would have some or all these characteristics:
- High water table & increased storage capacity
- High forage production
- Good shade-Cool water
- Good fish habitat-Good water quality
- High wildlife habitat diversity
- Vegetation & roots present to protect & stabilize banks
- Higher late summer stream flows
Principles of Riparian Management
There are many grazing strategies that have been devised to achieve specific ecological or management goals. These strategies can range from loosely supervised, season-long use to intensively managed multi-pasture rotational systems. It is very important to remember that the effectiveness of a given system with respect to sustainability, the restoration of ecosystem structure and diversity will depend upon the ecological characteristics of the stream system. With the exception of exclusion, there is no single grazing management strategy that has been proven to consistently improve degraded western riparian areas.
Because of the complexity of riparian zones devising proper grazing strategies is complicated. For example, under moderate, late season use, productivity and diversity of riparian meadows can be maintained. However, woody plant succession and growth on gravel bars could be hindered. Many grazing strategies fail to consider the proper length of the grazing period- this should be based on the areas cattle are actually using, not the entire area. For example, a study in northeastern Oregon showed that livestock preference and utilization was greatest (40-70%) for dry and moist meadows in late season grazing schemes. Willow-dominated gravel bars were intermediate in preferences with a utilization of 20-45% and the understory of mature cottonwood and alder communities were utilized at levels of less than 20%. Therefore, it is important to remember that management strategies should focus on the specific components of the ecosystem in need of restoration. It is recommended that these strategies be developed with interdisciplinary teams representing several disciplines. These would include, but not be limited to, range specialists, wildlife and or fisheries biologists, soil scientists, botanists, and foresters depending on the resources present in each area.
Generalized recommendations include:
- Tailor each grazing strategy to a particular stream or stream reach. Management objectives and components of the ecosystem that are of critical value must be identified (i.e. woody species recovery, streambank restoration, increased stream channel diversity, etc.) Other information that should be identified includes present vegetation, potential of the site for recovery, the desired future condition and the current factors that are causing habitat degradation or limiting its recovery.
- Describe the relationships between ecological processes that must function for riparian recovery. Assess factors affecting present condition (i.e., management stress versus natural stress) and what conditions will be needed to allow the stream to resume natural functions. Human caused factors that are causing stream degradation must be identified and changed.
- Design attainable goals, objectives, and management activities that will achieve the desired future condition of the riparian/stream ecosystem.
- Implement the plan.
- Design and implement a monitoring plan that will evaluate management, and allow for management corrections or modifications, as necessary.
In the development of riparian grazing systems, managers need to consider the forage base available to livestock and animal behavior. The easiest riparian zone to work with is one that is large enough to be fenced and used as a separate pasture where total control of livestock entry and exit is possible. These cases are rare, but they exist; they provide significant forage base (pounds per acre of forage) and flexibility in an operation. Flexibility may come in the form of forage quality needed for animal gain when surrounding uplands have matured and dried, or early in the season when uplands are sensitive to grazing. The riparian zone herbaceous plants should have adequate soil moisture available for regrowth when grazed at this time whereas uplands may not. Where riparian zones are narrow and fencing into a specialized pasture is impractical, late summer use may be detrimental. When the uplands are dry and of poor forage quality, animals tend to congregate in riparian zones where there is green forage. Woody riparian shrubs may provide the protein lacking in dried upland grasses. Also, cattle hesitate to climb the hills in search of forage when temperatures are hot, particularly where upland water is not developed or is of poor quality. Non-traditional grazing times may also be considered. In areas of intermittent or no snow cover, winter grazing is possible. Adequate supplementation has to be provided to prevent excessive browsing on woody plants. Up-slope water should also be considered. Early spring use during peak run-off periods is yet another option. Grazing is restricted near the stream by high flows. If the pasture is only used in the spring, then regrowth occurring after grazing should be available the following spring along with new growth to provide adequate quality and quantity of forage. The riparian zone vegetation remains ungrazed and protective.
Information and Ideas Were Taken From:
Riparian Areas: Perceptions in Management; Rangelands Vol. 9, No. 6, December 1987.
Wayne Elmore and Robert L. Beschta
Authors are, respectively, State riparian specialist, Bureau of Land Management, Prineville, OR 97754 and hydrologist, Oregon State University, Corvallis, OR 97331
Managing Change: Livestock Grazing On Western Riparian Areas.
Ed Chaney, Wayne Elmore, and William S. Platts, Ph.D.
Produced for the U.S. Environmental Protection Agency by the Northwest Resource Information, Center, Inc., P.O. Box 427 Eagle, Idaho 83616
Riparian and Watershed Systems: Degradation and Restoration in Ecological Implications of Livestock Herbivory in the West
Wayne Elmore and Boone Kauffman edited by Martin Vavra, William A. Laycock and Rex D. Pieper. Society for Range Management, Denver, CO.
Authors are, respectively, State riparian specialist, Bureau of Land Mangement, Prineville, OR 97754 and riparian specialist, Oregon State University, Corvallis, OR 97331
Riparian Areas Their Benefits and Uses, Sponsored by The Oregon Watershed Improvement Coalition.