, Volume 19, Issue 3, pp 545–559 | Cite as

Recent wetlands trends (1981/82–1994) in the Willamette Valley, Oregon, USA

  • Joseph A. Bernert
  • Joseph M. Eilers
  • Benn J. Eilers
  • Elaine Blok
  • Steven G. Daggett
  • Kenneth F. Bierly
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A two-stage, stratified, systematic sample design was implemented in the Willamette Valley, Oregon, USA, to quantify wetland and land-use changes from the 1980s to the 1990s. The Stage 1 sample (n=711) was drawn from public land survey sections and was stratified by land use and runoff potential. The Stage II sample (n=114) re-sampled the Stage I sample stratified by the amount of hydric soils identified in the Stage 1 sample. Wetland and upland classes were delineated on large-scale aerial photographs, digitized into ARC/Info coverages, and compared to quantify land-cover changes. Total loss of wetlands to uplands during the study period was about 3,800 ha, representing a 2.1 percent wetland loss from the 1980s. The net loss after adjusting for wetland gains was about 2,750 ha. During the study period, 70 percent of the wetland loss was associated with agriculture, six percent was lost to urbanization, and 24 percent was lost to other changes. The loss of wetlands to agriculture and the conversion of wetland types was consistent with a pronounced climatic component related to below-normal precipitation from 1985 to 1994, although continued installation of tile drains and expansion of irrigated agriculture also may have contributed to the changes. The loss of wetlands to agriculture raised questions regarding the effectiveness of current agricultural wetland policy, which appears ill-prepared to protect small wetlands or to deal with loss of wetlands from intensified use of existing farmland. This study identified a larger number and area of wetlands compared with national wetland surveys because of the larger scale data used in this study, the nature of the strata used in the statistical design, and the inclusion of palustrine farmed wetlands in the landuse classification.

Key Words

wetlands land use Willamette Valley Oregon wetland loss surveys 


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Literature cited

  1. Benner, P. A. and J. R. Sedell. 1997 Upper Willamette River landscape. A historic perspective. p. 23–47.In A. Laenen and D. A. Dunnette (eds.) River Quality: Dynamics and Restoration. Lewis Publishers, New York, NY, USA.Google Scholar
  2. Berry, B. J. L. and A. M. Baker. 1968. Geographic sampling. p. 91–100.In B. J. L. Berry and D. F. Marble. Spatial Analysis. Prentice-Hall, Inc., Englewood Cliffs, NJ, USA.Google Scholar
  3. Boyd, R. 1986. Strategies of Indian burning in the Willamette Valley. Canadian Journal of Anthropology 5:65–86.Google Scholar
  4. Clarke, W. E., D. White, and A. L. Schaedel. 1991. Oregon ecological regions and subregions for water quality management. Environmental Management 15:847–856.CrossRefGoogle Scholar
  5. Cochran, W. G. 1977. Sampling Techniques. Third Edition. John Wiley & Sons, New York, NY, USA.Google Scholar
  6. Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, USA. FWS/OBS-79/31.Google Scholar
  7. Dykaar, B. B. and P. J. Wigington, Jr. 1999: Floodplain formation and cottonwood colonization patterns on the Willamette River, Oregon, USA. Environmental Management: (in press).Google Scholar
  8. Frayer, W. E. 1991. Status and trends of wetlands and deepwater habitats in the conterminous United States. 1970s to 1980s. Michigan Technological University. Houghton, MI, USA.Google Scholar
  9. Frayer, W. E. and J. M. Hefner. 1991. Florida wetlands. Status and trends, 1970’s to 1980’s. U.S. Department of Interior, Fish and Wildlife Service, Southeast Region, Atlanta, GA, USA.Google Scholar
  10. Gabriel, J. T. 1993. A modified synoptic analysis of the status of Oregon’s Willamette Valley Wetlands. Master’s Degree Research Paper. Oregon State University, Corvallis, OR, USA.Google Scholar
  11. Gedrey, D. R. and B. A. Hiserte. 1989. Changes in land use in western Oregon between 1971–74 and 1982. USDA Forest Service, Corvallis, OR, USA. Resource Bulletin PNW-RB-165.Google Scholar
  12. Gilbert, R. O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand Reinhold Co., New York, NY, USA.Google Scholar
  13. Habeck, J. R. 1961. The original vegetation of the Mid-Willamette Valley, Oregon. Northwest Science 35:65–77.Google Scholar
  14. Hagood, M. J. and E. H. Bernert. 1945. Component indexes as a basis for stratification in sampling. Journal of the American Statistical Association 40:330–341.CrossRefGoogle Scholar
  15. Hall, J. V., W. E. Frayer, and B. O. Wilen. 1994. Status of Alaska wetlands. U.S. Fish and Wildlife Service, Alaska Region. Anchorage, AK, USA.Google Scholar
  16. Hefner, J. M., B. O. Wilen, T. E. Dahl and W. E. Frayer. 1994. Southeast wetlands. Status and Trends, mid-1970’s to mid-1980’s. U.S. Dept. of the Interior Fish and Wildlife Service, Atlanta, GA, USA and U.S. Environmental Protection Agency. Atlanta, GA, USA.Google Scholar
  17. Holland, C. C., J. E. Honea, S. E. Gwin and M. E. Kentula. 1995. Wetland degradation and loss in the rapidly urbanizing area of Portland, Oregon. Wetlands 15:336–345.CrossRefGoogle Scholar
  18. Johannessen, C. L., W. A. Davenport, A. Millet, and S. McWilliams. 1970. The vegetation of the Willamette Valley. Annals of the Association of American Geographers 61:286–302.CrossRefGoogle Scholar
  19. Kagan, J. and S. Caicco. 1992. Manual of Oregon Actual Vegetation. Draft Report prepared for the Oregon Gap Analysis Program. Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Moscow, ID, USA in cooperation with the Oregon Department of Fish and Wildlife and the Oregon Natural Heritage Program, Portland, OR, USA.Google Scholar
  20. Kentula, M. E., J. C. Sifneos, J. W. Good, M. Rylko, and K. Kunz. 1992. Trends and patterns in Section 404 permitting requiring compensatory mitigation in Oregon and Washington, USA. Environmental Management 16:109–119.CrossRefGoogle Scholar
  21. Leibowitz, N. 1995. Oregon’s Wetland Conservation Strategy: Issue analysis, public discussions & recommendations. Division of State Lands. Salem, OR, USA.Google Scholar
  22. Newell, A. D. and J. A. Bernert. 1996. Oregon Lakes: Overview to Special Lake Issue. Northwest Science 70:1–12.Google Scholar
  23. Quenouille, M. H. 1949. Problems in plane sampling. Annals of Mathematical Statistics 20:355–375.CrossRefGoogle Scholar
  24. Sedell, J. R. and J. L. Froggatt. 1984. Importance of streamside forest to large rivers: the isolation of the Willamette River, Oregon USA from its floodplain by snagging and streamside forest removal. Verhandlungen der Internationalen Vereinigung fur Theoretische und Angewandte Limnologic (International Association of Theoretical and Applied Limnology) 22:1828–1834.Google Scholar
  25. Shaich, J. A. and K. T. Franklin. 1995. Wetland compensatory mitigation in Oregon: A program evaluation with a focus on Portland Metro projects. Division of State Lands, Salem, OR, USA.Google Scholar
  26. Taylor, G. H. 1998. Impacts of El Niño/Southern Oscillation on the Pacific Northwest. http://www.ocs.orst.edu/reports/enso_pnw.html.Google Scholar
  27. Tiner, R. W. 1997. NWI maps: What they tell us. National Wetlands Newsletter 19(2):7–12.Google Scholar
  28. Tolman, J. 1997. How we achieved no net loss. National Wetlands Newsletter 19(4):1.Google Scholar
  29. U.S. Department of Agriculture. 1992a. 1992 National Resources Inventory. NRI Backgrounder. USDA Soil Conservation Service, Washington, DC, USA.Google Scholar
  30. U.S. Department of Agriculture. 1992b. State Soil Geographic Data Base (STATSGO) of Oregon. USDA. Soil Conservation Service, Washington, DC, USA.Google Scholar
  31. U.S. Fish and Wildlife Service. 1997. Status and Trends of Wetlands in the Conterminous United States: Projected Trends 1985 to 1995. U.S. Fish and Wildlife Service. Washington, DC, USA. Draft Report to Congress.Google Scholar
  32. U.S. Fish and Wildlife Service. 1994. Continuous Wetland Trend Analysis Project Specifications (Photointerpretation and Cartographic Conventions). St. Petersburg, FL, USA.Google Scholar
  33. U.S. Fish and Wildlife Service. 1991. Status of National Wetlands Inventory: Region 1. Portland, OR, USA.Google Scholar

Copyright information

© Society of Wetland Scientists 1999

Authors and Affiliations

  • Joseph A. Bernert
    • 1
  • Joseph M. Eilers
    • 1
  • Benn J. Eilers
    • 1
  • Elaine Blok
    • 2
  • Steven G. Daggett
    • 3
  • Kenneth F. Bierly
    • 4
  1. 1.E&S Environmental Chemistry, IncCorvallisUSA
  2. 2.U.S. Fish and Wildlife ServicePortlandUSA
  3. 3.SRI/SHAPIRO/AGCO, Inc.PortlandUSA
  4. 4.Oregon Division of State LandsSalemUSA

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