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dc.contributor.authorSymstad, Amy J.
dc.contributor.authorWienk, Cody L.
dc.contributor.authorThorstenson, Andy D.
dc.date.accessioned2020-09-05T07:12:45Z
dc.date.available2020-09-05T07:12:45Z
dc.date.issued2008-07-01
dc.identifier.citationSymstad, A. J., Wienk, C. L., & Thorstenson, A. D. (2008). Precision, repeatability, and efficiency of two canopy-cover estimate methods in northern Great Plains vegetation. Rangeland Ecology & Management, 61(4), 419-429.
dc.identifier.issn0022-409X
dc.identifier.doi10.2111/08-010.1
dc.identifier.urihttp://hdl.handle.net/10150/642969
dc.description.abstractGovernment agencies are subject to increasing public scrutiny of land management practices. Consequently, rigorous, yet efficient, monitoring protocols are needed to provide defensible quantitative data on the status and trends of rangeland vegetation. Rigor requires precise, repeatable measures, whereas efficiency requires the greatest possible information content for the amount of resources spent acquiring the information. We compared two methods—point frequency and visual estimate—of measuring canopy cover of individual plant species and groups of species (forbs vs. graminoids, native vs. nonnative) and plant species richness. These methods were compared in a variety of grassland vegetation types of the northern Great Plains for their precision, repeatability, and efficiency. Absolute precision of estimates was similar, but values generally differed between the two sampling methods. The point-frequency method yielded significantly higher values than the visual-estimate method for cover by individual species, graminoid cover, and total cover, and yielded significantly lower values for broadleaf (forb + shrub) cover and species richness. Differences in values derived by different sampling teams using the same method were similar between methods and within precision levels for many variables. Species richness and median species cover were the major exceptions; for these, the point-frequency method was far less repeatable. As performed in this study, the visual-estimate method required approximately twice the time as did the point-frequency method, but the former captured 55% more species. Overall, the visual-estimate method of measuring plant cover was more consistent among observers than anticipated, because of strong training, and captured considerably more species. However, its greater sampling time could reduce the number of samples and, therefore, reduce the statistical power of a sampling design if time is a limiting factor. 
dc.language.isoen
dc.publisherSociety for Range Management
dc.relation.urlhttps://rangelands.org/
dc.rightsCopyright © Society for Range Management.
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectgrasslands
dc.subjectobserver error
dc.subjectplant canopy cover
dc.subjectpoint-frequency model
dc.subjectvegetation monitoring
dc.subjectvisual estimates
dc.titlePrecision, Repeatability, and Efficiency of Two Canopy-Cover Estimate Methods in Northern Great Plains Vegetation
dc.typetext
dc.typeArticle
dc.identifier.journalRangeland Ecology & Management
dc.description.collectioninformationThe Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.
dc.eprint.versionFinal published version
dc.description.admin-noteMigrated from OJS platform August 2020
dc.source.volume61
dc.source.issue4
dc.source.beginpage419-429
refterms.dateFOA2020-09-05T07:12:45Z


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