An assessment of some improved techniques for estimating the abundance (frequency) of sedentary organisms

Morrison, David A. and Le Brocque, Andrew F. and Clarke, Peter J. (1995) An assessment of some improved techniques for estimating the abundance (frequency) of sedentary organisms. Vegetatio, 120 (2). pp. 131-145. ISSN 0042-3106


The traditional sampling method for estimating frequency (the number of sub-quadrats containing a basal part of the
organisms) is compared, using both computer simulations and direct comparison in the field, to two new methods that use a compound series of variable-sized concentric sub-quadrats. Both the new frequency-score and the new
importance-score methods are closer approximations of density than is the standard frequency method, and the
estimates produced by both of the new methods are less affected by the choice of sub-quadrat size and the spatial
distribution (dispersion) of the organisms (i.e. clumping and regularity). Thus, the two nested-quadrat methods
appear to ameliorate the usual frequency limitations associated with sub-quadrat size and organism dispersion, by
the use of a range of different sub-quadrat sizes. This is important in community studies, where the component
species may show a wide range of densities and dispersions. Both of the new methods are easily employed in the
field. The importance-score method involves no more sampling effort than does standard qualitative (presenceabsence)sampling, and it can therefore be used to sample a larger quadrat area than would normally be used for frequency sampling. This makes the method much more cost-effective as a means of estimating abundance, and it allows a greater number of the rarer species to be included in the sampling. The frequency-score method is more time-consuming, but it is capable of detecting more subtle community patterns. This means that it is particularly useful for the study of species-poor communities or where small variations in composition need to be detected.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Author version not held.
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 09 Apr 2010 12:20
Last Modified: 14 Nov 2013 06:43
Uncontrolled Keywords: abundance; frequency; frequency-score; importance-score; presence-absence; sampling
Fields of Research : 06 Biological Sciences > 0602 Ecology > 060208 Terrestrial Ecology
05 Environmental Sciences > 0501 Ecological Applications > 050102 Ecosystem Function
06 Biological Sciences > 0602 Ecology > 060202 Community Ecology(excl. Invasive Species Ecology)
Socio-Economic Objective: D Environment > 96 Environment > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified
D Environment > 96 Environment > 9605 Ecosystem Assessment and Management > 960599 Ecosystem Assessment and Management not elsewhere classified
Identification Number or DOI: 10.1007/BF00034343

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