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Communication at the NABS Annual meeting, Keystone, 2000
(78) APPLICATION OF HISTORICAL CHANNEL AND FOREST CHANGE, FISH ASSEMBLAGES, AND SOCIOECONOMIC PATTERNS IN RESTORATION OF LARGE RIVERS.
S.V. Gregory, R.C. Wildman, L.R. Ashkenas, P. Minear, and D. Oetter. Department of Fisheries & Wildlife, Oregon State University
Floodplain forests and channels have been extensively altered in world rivers. Historical patterns can be used as references for restoration. We present an analysis of historical changes in 290 km of the mainstem Willamette River, Oregon. Based on river surveys from 1850, 1895, 1932, and 1995, we determined amount of channel change, major geomorphic reaches, and associated changes in floodplain forests. We surveyed fish assemblages in multiple channel, tributary junction, and single channel reaches. Three major geomorphic reaches in the Willamette mainstem showed distinct patterns of either loss or gain in complexity. Forests declined sharply in all reaches. Channel complexity decreased in the upstream reach, varied in the middle, and increased slightly in the downstream reach. Large-scale landforms exerted major controls on relative patterns of change. Tributary junctions and multiple channel reaches contained greater fish richness. Proportions of exotic species and fish with abnormalities increased downstream. We used these data to screen the mainstem river for restoration of floodplain forests and channels. Biophysical analyses were integrated with measures of demographic pressures (structures, roads, urban growth) and economic values (property values, land use types). Integration of biophysical and socioeconomic properties of rivers has major implications for long-term success in river restoration.
Presented at 8:00 AM on Tuesday, May 30, 2000 in River and Stream Restoration
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