Wetlands

, Volume 18, Issue 3, pp 329–334 | Cite as

Bias in quadrat-derived estimates of number of prairie wetlands

  • Rex R. Johnson
  • Kenneth F. Higgins
Article
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Abstract

Estimates of number of wetlands derived from quadrat sampling are inherently biased when wetlands on quadrat boundaries are counted. Bias complicates comparisons of wetland density or abundance between years or studies, or between regions with different wetland sizes. Simulated quadrat sampling was conducted to evaluate the magnitude of bias in estimates of the number of temporary, seasonal, semipermanent, and total wetlands from samples of square quadrats of different sizes. All estimates were biased except for number of temporary wetlands derived from samples of the largest quadrats. Bias ranged from +101% (SE=0.39%) for estimates of the number of semipermanent wetlands sampled with 0.64 km2 quadrats to +0.19% (SE=0.19%) for the number of temporary wetlands sampled with 25.60 km2 quadrats. Bias was greatest when large wetlands were sampled using small quadrats and was related to quadrat perimeter: area ratio (km/km2) and to quadrat size. Managers and researchers should correct for bias in estimates of number of wetlands by deriving correction factors with the equations presented or by deriving correction factors using aerial photographs to determine the geometric centers of wetlands in and around a subset of sample quadrats.

Key Words

bias correction estimation prairie pothole region South Dakota quadrat sampling wetland 
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Literature Cited

  1. Besag, J. and J. T. Gleaves. 1973. On the detection of spatial patterns in plant communities. Bulletin of the International Statistical Institute 45:153–158.Google Scholar
  2. Brewster, W. G., J. M. Gates, and L. D. Flake. 1976. Breeding waterfowl populations and their distribution in South Dakota. Journal of Wildlife Management 40:50–59.CrossRefGoogle Scholar
  3. Cowardin, L. M. 1982. Some conceptual and semantic problems in wetland classification and inventory. Wildlife Society Bulletin 10:57–60.Google Scholar
  4. Cowardin, L. M., D. S. Gilmer, and C. W. Shaiffer. 1985. Mallard recruitment in the agricultural environment of North Dakota. Wildlife Monogrphs 92.Google Scholar
  5. Cowardin, L. M., D. S. Gilmer, and L. M. Mechlin. 1981. Characteristics of central North Dakota Wetlands determined from sample aerial photographs and ground study. Wildlife Society Bulletin 9:280–288.Google Scholar
  6. Cowardin, L. M., D. H. Johnson, A. M. Frank, and A. T. Klett. 1983. Simulating results of management actions on mallard productivity. Transactions of the North American Wildlife and Natural Resources Conference 48:257–272.Google Scholar
  7. Cowardin, L. M., T. L. Shaffer. and P. M. Arnold. 1995. Evaluation of duck habitat and estimation of duck population sizes with a remote-sensing-based system. National Biological Service, Washington, DC, USA. Biological Science Report No. 2.Google Scholar
  8. Diggle, P. J. 1975. Robust density estimation using distance methods. Biometrika 62:39–48.CrossRefGoogle Scholar
  9. Hammack, J. and G. M. Brown, Jr. 1974. Waterfowl and wetlands: toward bioeconomic analysis. Resources for the Future, Inc., Washington, DC, USA.Google Scholar
  10. Johnson, D. H. and J. W. Grier. 1988. Determinants of breeding distributions of ducks. Wildlife Monographs 100.Google Scholar
  11. Johnson, R. R., and K. F. Higgins. 1997. Wetland Resources of Eastern South Dakota. South Dakota State University, Brookings, SD, USA.Google Scholar
  12. Krebs, C. J. 1989. Ecological Methodology. Harper Collins Publishers, New York, NY, USA.Google Scholar
  13. Martin, F. W., R. S. Pospahala, and J. D. Nichols. 1979. Assessment and population management of North American migratory birds. p. 187–239.In J. Cairns, Jr., G. P. Patil, and W. E. Waters (eds.) Environmental Biomonitoring. Assessment, Prediction, and Management—Certain Case Studies and Related Quantitative Issues. International Cooperative Publishing House, Fairland, MD, USA.Google Scholar
  14. Ruwaldt, J. J., Jr., L. D. Flake, and J. M. Gates. 1979. Waterfowl use of natural and man-made wetlands in South Dakota. Journal of Wildlife Management 43:375–383.CrossRefGoogle Scholar
  15. SAS Institute, Inc. 1989. SAS/STAT User’s Guide, Version 6. Fourth ed. SAS Institute, Inc., Cary, NC, USA.Google Scholar
  16. Sugden, L. G. and G. Butler. 1980. Estimating densities of breeding canvasbacks and redheads. Journal of Wildlife Management 44:814–821.CrossRefGoogle Scholar
  17. U.S. Fish and Wildlife Service and Canadian Wildlife Service. 1987. Standard operating procedures for waterfowl population and habitat surveys in North America. U.S. Fish and Wildlife Service and Canadian Wildlife Service, Office of Migratory Bird Management, Laurel, MD, USA.Google Scholar
  18. Weigert, R. G. 1962. The selection of an optimal quadrat size for sampling the standing crop of grasses and forbs, Ecology 43:125–129.CrossRefGoogle Scholar

Copyright information

© Society of Wetland Scientists 1998

Authors and Affiliations

  • Rex R. Johnson
    • 1
  • Kenneth F. Higgins
    • 2
  1. 1.Department of Wildlife and Fisheries SciencesSouth Dakota State UniversityBrookingsUSA
  2. 2.South Dakota Cooperative Fish and Wildlife Research Unit U.S. Geological Survey-Biological Resources DivisionSouth Dakota State UniversityBrookingsUSA

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