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In the eye of the b...
In the eye of the beholder : bias and stochastic variation in cover estimates
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- Bergstedt, Johan (författare)
- Linköpings universitet,Ekologi,Tekniska högskolan
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- Westerberg, Lars (författare)
- Linköpings universitet,Ekologi,Tekniska högskolan
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- Milberg, Per (författare)
- Swedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Linköpings universitet,Ekologi,Tekniska högskolan,Institutionen för växtproduktionsekologi,Department of Crop Production Ecology,Linköping University
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(creator_code:org_t)
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- 2009-03-17
- 2009
- Engelska.
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Ingår i: PLANT ECOLOGY. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 204:2, s. 271-283
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Abstract
Ämnesord
Stäng
- Cover estimates by eye is a prevailing method to assess abundance. We examined cover estimates with regard to bias and random variation. Ten observers working with a national forest vegetation survey estimated sixteen 100 m(2)-plots, placed in two different vegetation types. These had similar species composition but were clearly distinguishable in the field. In species-wise analyses, observer bias varied greatly, with Dicranum spp., Vaccinium vitis-idaea and Vaccinium myrtillus having the largest bias. Experience had a surprisingly small impact on variation. Power analysis revealed only small differences between observers in the ability to distinguish the two vegetation types, and little value in averaging the assessments from two, three or four observers. Cover estimates did better than presence/absence data in separating the two vegetation types and multivariate analyses were more powerful than univariate ones.
Ämnesord
- LANTBRUKSVETENSKAPER -- Lantbruksvetenskap, skogsbruk och fiske -- Skogsvetenskap (hsv//swe)
- AGRICULTURAL SCIENCES -- Agriculture, Forestry and Fisheries -- Forest Science (hsv//eng)
- NATURVETENSKAP -- Biologi -- Ekologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Ecology (hsv//eng)
Nyckelord
- Forest vegetation
- Observer bias
- Statistical power
- Sweden
- Visual assessment
- NATURAL SCIENCES
- NATURVETENSKAP
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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