fire, management of exotic species invasions, and large herbivore management may be necessary to maintain natural characteristics and functions and to sustain them over time. Because degraded riparian areas are so prevalent in many portions of the nation, protecting any that remain relatively uninfluenced by human perturbations should be a high priority. Measures to protect intact areas are often relatively easy to implement, have a high likelihood of being successful, and are less expensive than the restoration of degraded systems (NRC, 1992; Cairns, 1993).
Definitions of the verb restore commonly include to reestablish, to put back into existence or use, to bring back into the former or original state, to renew, to repair into nearly the original form, and to bring back into a healthy state. These definitions point to the reestablishment of former conditions, processes, and functions (i.e., making healthy again). Although seemingly simple in concept, the restoration of degraded riparian areas is often a scientific and social challenge. In some instances, the natural or pristine conditions of a particular riparian area may no longer exist or may not be known with certainty. In others, multiple causes of degradation may have occurred over long periods of time—hence, cause-and-effect relationships that define existing conditions may not be well known or easy to decipher at either local or landscape scales.
Restoration may refer both to the process of repairing degraded riparian areas and to the desired end goal of such actions, although the term is sometimes used to refer only to the latter. Thus, for example, NRC (1992) defined restoration of aquatic ecosystems as representing the “re-establishment of pre-disturbance aquatic functions and related physical, chemical, and biological characteristics.” It further indicated that “restoration is different from habitat creation, reclamation, and rehabilitation—it is a holistic process not achieved through the isolated manipulation of individual elements.” This definition has the stated goal of regaining predisturbance characteristics, which this report categorizes specifically as ecological restoration. Thus, a working definition of ecological restoration for riparian areas, based upon the above as well as upon definitions within Jackson et al. (1995), Kauffman et al. (1997), and Williams et al. (1997) might be:
The reestablishment of predisturbance riparian functions and related physical, chemical, and biological linkages between aquatic and terrestrial ecosystems; it is the repairing of human alterations to the diversity and dynamics of indigenous ecosystems. A fundamental goal of riparian restoration is to facilitate self-sustaining occurrences of natural processes and linkages among the terrestrial, riparian, and aquatic ecosystems.
Ecological restoration of riparian areas results in the reestablishment of functional linkages between organisms and their environment, even though these