Reproducibility of species lists, visual cover estimates and frequency methods for recording high mountain vegetation

Details

Serval ID
serval:BIB_BBE75779FC73
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Reproducibility of species lists, visual cover estimates and frequency methods for recording high mountain vegetation
Journal
Journal of Vegetation Science
Author(s)
Vittoz P., Bayfield N., Brooker R., Elston D.A., Duff E.I., Theurillat J.-P., Guisan A.
ISSN
1100-9233
Publication state
Published
Issued date
2010
Peer-reviewed
Oui
Volume
21
Number
6
Pages
1035-1047
Language
english
Abstract
Question: When multiple observers record the same spatial units of alpine vegetation, how much variation is there in the records and what are the consequences of this variation for monitoring schemes to detect change?
Location: One test summit in Switzerland (Alps) and one test summit in Scotland (Cairngorm Mountains).
Method: Eight observers used the GLORIA protocols for species composition and visual cover estimates in percent on large summit sections (>100 m2) and species composition and frequency in nested quadrats (1 m2).
Results: The multiple records from the same spatial unit for species composition and species cover showed considerable variation in the two countries. Estimates of pseudoturnover of composition and coefficients of variation of cover estimates for vascular plant species in 1m x 1m quadrats showed less variation than in previously published reports whereas our results in larger sections were broadly in line with previous reports. In Scotland, estimates for bryophytes and lichens were more variable than for vascular plants.
Conclusions: Statistical power calculations indicated that, unless large numbers of plots were used, changes in cover or frequency were only likely to be detected for abundant species (exceeding 10% cover) or if relative changes were large (50% or more). Lower variation could be reached with the point methods and with larger numbers of small plots. However, as summits often strongly differ from each other, supplementary summits cannot be considered as a way of increasing statistical power without introducing a supplementary component of variance into the analysis and hence the power calculations.
Keywords
Accuracy, Biodiversity monitoring, Observer bias, Permanent plot, Pseudo-turnover, Sampling error, Statistical power
Web of science
Create date
24/08/2010 14:57
Last modification date
20/08/2019 15:29
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