Riparian Ecosystem Creation and Restoration:
A Literature Summary
Planning
Two factors are especially important before one can either identify a problem or begin recovery processes in riparian ecosystems: (1) knowledge of the management objectives and (2) knowledge of the physical environment and biotic communities occupying the site, including the hydrologic regime, physical and chemical characteristics of the soils and substrates, potential for the site to support particular species and plant communities, and vegetation successional patterns (Chapman et al. 1982).
Creation of some riparian ecosystems may be extremely limited due to the difficulty of creating necessary hydrologic conditions. For example, Cooper (1988) doubts that Rocky Mountain peatlands can be restored once peat has been removed. Peat accumulation rates in Rocky Mountain wetlands range from 2,000-5,000 years per meter of peat. Cooper also doubts that the peatland ecosystem could be initiated in today's dry climate of the West. An important factor to consider in decisions of whether or not mountain wetlands can be created is that most fens in the Rocky Mountains today occur in sites where groundwater discharge occurs. This groundwater discharge alone may be sufficient to saturate wetland soils, or more likely the groundwater together with surface water are necessary for continued soil saturation. All sites that have significant groundwater discharge most likely are already wetlands, and a groundwater discharge situation cannot be created.
Plans to restore stream and riparian ecosystems should entail evaluations of the watershed (Platte et al. 1987b). Within a given watershed, the manner in which water and sediment move is influenced by the geomorphic parameters of valleys. The frequency and duration of flooding (water-regime) determine the distribution of contrasting riparian community types (e.g., forested, shrub, and herbaceous).
Anderson and Ohmart (1979) present six basic ingredients for adequate riparian ecosystem mitigation planning: (1) a solid base of data concerning wildlife in the project area and in the area set aside for mitigation; (2) a thorough analysis of the data; (3) creation of predictive models with which to create, in theory, a design for the mitigation; (4) design of required modifications, including site preparation (e.g., clearing, rootripping, leveling, installing an irrigation system), equipment needs, costs, and a careful analysis of probable delays; (5) design implementation, including labor requirements and labor sources; and (6) monitoring, including methods of gathering information, analytical and interpretive techniques, and staff requirements.
Mitigation plans for which adequate funds are not available should not be proposed or, if proposed, the shortage of funds should be explicit (Anderson and Ohmart 1985). The contracting agency should select a contractor whose mitigation proposal has a high chance of success rather than selecting the contractor with the lowest bid. Landowner cooperation is necessary for habitat restoration on private lands and the landowner's interests should be identified and incorporated into the project design.
When planning a creation or restoration project, close proximity to existing high quality riparian ecosystems is advantageous for the added benefit of recolonization. For example, an existing riparian ecosystem was destroyed when a portion of the Carrolls Channel on the Columbia River, Washington, was inadvertently filled during dredge emergency actions following the 1980 eruption of Mount St. Helens (U.S. Fish and Wildlife Service 1983). The contractor was required to remove the fill material to restore previous elevations. The newly created channel was graded into a small natural channel with a number of desirable emergent species. Silt from the Columbia River deposited over much of the area and by 1983 recolonization of plants and use by wildlife was far greater than expected.
Platts et al. (1987b) recommended that preliminary planning involve developers, contractors, engineers, environmental scientists, and representatives of regulatory agencies. The scope, goals, objectives, and general approach to restoration should be established during this preliminary stage.
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