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<br />WATERSHED RESTORATION
<br />in and around stream channels, the influence of those
<br />manipulations on trout densities was insignificant and
<br />actually hurt the natural restoration process of the riparian
<br />and stream ecosystem (Beschta et al. 1994; Inter-Fluve 1995;
<br />W. S. Platts, Don Chapman and Consultants, personal
<br />communications).
<br />Livestock grazing has been perhaps the most prevalent
<br />cause of ecological degradation for many western riparian
<br />and stream ecosystems (Kauffman and Krueger 1984;
<br />Kauffman 1988; Fleischner 1994). After extensive field
<br />reviews of fish habitat improvement projects in eastern
<br />Oregon, Beschta et al. (1991) and Kauffman et al. (1993)
<br />concluded that the cessation of livestock grazing in ripari-
<br />an zones of eastern Oregon vas the single most ecological-
<br />ly effective approach to restoring salmonid habitats.
<br />While many reviews of grazing effects on riparian veg-
<br />etation have been general in nature (e.g., Platts 1991;
<br />Elmore and Kauffman 1994), recent research is providing
<br />improved insights into the effects of grazing on woody
<br />riparian species. This research is important because wil-
<br />lows, cottomvoods, and alders are significant features of
<br />terrestrial wildlife habitat, stream channel morphology,
<br />and aquatic habitat. In central Oregon, Busse (1989) found
<br />a lack of willow and cottonwood reproduction in grazed
<br />misinterpreting ecosystem needs is
<br />common with many instream
<br />rehabilitation and ::enhancement
<br />programs
<br />riparian zones of the Crooked River National Grassland.
<br />After constntcting corridor fencing, she recorded a wide-
<br />spread and rapid rate of willow and cottonwood establish-
<br />ment. In northeast Oregon, similar rates of woody species
<br />recovery after cattle grazing stopped have been quantified
<br />(Green and Kauffman 1995; Case and Kauffman, in press).
<br />Three years after cattle grazing stopped on Meadotiv Creek
<br />(a tributary of the Grande Ronde River), Case and Kauff-
<br />man (in press) reported that the average crown volume o.`
<br />«-illo~ws increased nearly 300`-~. A~•erage crotivn volume of
<br />black cottonwood and alder increased X00 ~ and 2009,
<br />_spetti~-el-. Comparing 10 year of no ,razing kith light
<br />to moderate late-season grazing use ii; northeast Oregon,
<br />Green and Kauffman (199~~ reported significant increases
<br />in both the density and stnuhiral complexity of willo~~•s
<br />and cottonwoods in ungrazed exclosures. Although posi-
<br />tive trends in willow density and height also occurred in
<br />the lightly to moderately grazed areas (three weeks annu-
<br />ally late in the season), recovery rates were significantly
<br />less than those of the ungrazed areas.
<br />Reviews of instream habitat management projects
<br />throughout the western United States clearly indicate that
<br />passive restoration has been the critical first step in suc-
<br />cessful riparian restoration programs (Beschta et al. 1991;
<br />Kauffman et a1. 1993; Beschta et al. 1994). In many cases,
<br />this eras all that ryas needed to initiate restoration of ripar-
<br />_.i^, e~~osystems. Bzcause of the high costs and potential for
<br />failure with active restoration and manipulation, we rec-
<br />ommended that project managers monitor and observe the
<br />natural recovery process for an appropriate period oftime
<br />(e.g., 10 years) after implementing passive restoration.
<br />Then, if managers ascertain that natural recovery is limit-
<br />ed or not occurring, implementation of active restoration
<br />projects might begin.
<br />Active Restorrltio~i
<br />After implementing passive restoration, a site still may
<br />remain in an ecological state that is unlike what would
<br />occur naturally (Figures 2 and 3). These situations can
<br />occur when an ecosystem is sufficiently degraded such
<br />that the i~lherent capacity to recover has been lost. To
<br />achieve ecological restoration in such situations, active
<br />manipulations ~vill be necessary.
<br />Many factors may prevent a return to a natural dynam-
<br />ic system when using only passive restoration-species
<br />extinctions [particularly keystone species such as cotton-
<br />wood or beaver (Cn~tor eannden;is)], exotic predators
<br />[smallmouth bass or bullfrogs (Rnnn cntesheiana)], exotic
<br />competitors [carp (Ci/E~rinus cnryio), reed canary grass
<br />(Phnlnris nrundinncen), or knapweeds (Certtnttren spp.)], loss
<br />of hydrologic function and alteration of hydrologic distur-
<br />bance regimes (e.g., diversions, regulated flows by dams,
<br />disruptions of groundwater flow patterns), and alteration
<br />of geomorphic features (e.g., channel incision, soil erosion,
<br />compaction). tiVhile some of these barriers to recovery
<br />might be easily ameliorated, others can be sufficiently
<br />severe in their magnitude and persistence that restoration
<br />may not be technologically feasible.
<br />Biotic manipulations representing active ecological
<br />restoration include the reintroduction of beaver or plant
<br />species that have been extirpated from the area. Reintro-
<br />ductions are most successful when a feasibility analysis
<br />has confirmed that suitable habitat is present for the
<br />organism to be reintroduced. In the case of beaver, ade-
<br />quate habitat conditions inchide sufficient availability of
<br />forme and suitable structure of riparian plant communi-
<br />ties. If introduced into degraded or recovering ecosystems
<br />before «~oodv species have sufficiently reestablished,
<br />beaver can actually limit ecological recovery (Kauffman et
<br />al. 19>?; Case L°~~. ~lternati~: e1~; «•hen reintroduced in
<br />suitable riparian habitat conditions, file beaver can dra-
<br />matically accelerate the restoration process through its
<br />influence on the hydrology, ~retland extent, species com-
<br />position, and quality of salmonid habitats (Naiman et al.
<br />1988; Lowry 199 ~).
<br />Vegetation plantings are a commonly proposed restora-
<br />tion technique. Ho~yever, after passive restoration is
<br />implemented, the natural capacity for rapid reinvasion of
<br />woody species on suitable sites often makes artificial
<br />plantings unnecessary (Busse 1989; Schulz and Leineger
<br />1990; Case and Kauffman, in press). Where shrubs and
<br />other goody species have been eliminated and the poten-
<br />tial for natural reinvasion no longer exists, active revegeta-
<br />tion will be required. For example, ~rhere high-flow
<br />regimes ha~•e been si` ni`icantl~ altered (e.g., below a
<br />- =~- ~~ecial Issu? o^. VYat?rs~~~?r r estora'i ~~ Fisheries ~= ~ ;
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