Mana, D.
A test application of the SHE method as a biostratigraphical parameter

Geo.Alp 2, 2005, p. 99–106

Biodiversity – the index "expressing the variety and variability of living organisms and of the ecological systems comprising them" (Ferrari, 2001) – is essential in the characterization and study of past and present biological systems, and is generally expressed by a number (the "biodiversity index"), statistically derived from empirical observations.
The SHE indexing method (Buzas & Hayek, 1996, Hayek & Buzas 1997), is expressed by the Shannon Index, H (a measure of the system’s entropy) as the composition of two factors representing respectively the number of species in the sample (S) and the distribution uniformity (E).
The SHE index does not only describe in a thorough way the system’s biodiversity, but, as a function of abundance and evenness, can be used to identify biofacies (SHEBI – SHE for Biofaces Identification) or to characterize the whole structure of the analysed community (SHECSI – SHE for Community Structure Identification).
SHE analysis, independently of its application purposes, appears to be highly flexible, does not require the adoption of specific computer packages beyond a common spreadsheet, and is based on a simple graphical analysis; widely adopted in botanics, SHEBI analysis in particular has been applied with satisfactory results to the study of benthic foraminiferal faunas from the Atlantic ocean (Buzas & Hayek,1998].
In this work, the SHEBI method has been applied to 87 samples from the Falconara section (Southern Sicily) – the purpose of the study is to verify the possibility of applying SHE/SHEBI to Messinian planktonic foraminiferal assemblages.
Our study has to face issues that are typical of planctonic faunas – such as the lower number of species and the ample variability in single taxa abundances; a further factor to be taken into account in setting up and executing the analysis is the progressive deterioration of the ecosystem as the peak of the Messinian crisis approaches. Biofacies identification through SHEBI in less than ideal conditions, but on such a widely studied and described section, offers an excellent opportunity to test the method and its limits, its application range and the reliability of its results.

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