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An extension of presence/absence coefficients to abundance data: a new look at absence
Author(s) -
Tamás Júlia,
Podani János,
Csontos Péter
Publication year - 2001
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.2307/3236854
Subject(s) - contingency table , extension (predicate logic) , chronosequence , similarity (geometry) , abundance (ecology) , mathematics , table (database) , statistics , relative species abundance , ecology , computer science , data mining , biology , ecological succession , artificial intelligence , programming language , image (mathematics)
Abstract. Alternative community analyses, based on quantitative and presence/absence data, are comparable logically if the data type is the only factor responsible for differences among results. For presence/absence indices that consider mutual absences, no quantitative alternatives are known. To facilitate such comparisons, a new family of similarity coefficients is proposed for abundance data. Formally, this extension is achieved by generalizing the four cells of the usual 2 × 2 contingency table to the quantitative case. This implies an expanded meaning of absence: for a given species at a given site it is understood as the difference between the actual value and the maximum detected in the entire study. The correspondence between 10 presence/absence coefficients and their quantitative counterparts is evaluated by graphical comparisons based on artificial data. The behaviour of the new functions is also examined using field data representing post‐fire regeneration processes in grasslands and a chronosequence pertaining to forest regeneration after clear‐cut. The examples suggest that the new coefficients are most informative for data sets with low beta‐diversity and temporal background changes.