Can Ellenberg’s indicator values for Mediterranean plants be used outside their region of definition?

Sandrine Godefroid, Elías Dana

Onderzoeksoutput: Articlepeer review

43 Citaten (Scopus)

Samenvatting

Aim The aims of the present study are: (1) to explore the relationships between the Ellenberg indicator values (light, temperature and moisture) recently developed for two different Mediterranean regions (Italy and Greece); (2) to evaluate the possibillity of using these values in other Mediterranean areas.

Methods A global matrix containing 966 items of information (161 species x 3 indicator variables x 2 values assigned in each study, one e-in Italy and one in Greece) was constructed. A test of the accuracy of the values in predicting actual environmental conditions was provided by a DCA on published vegetation relevés from the Mediterranean region. To express relationships in ecological indicator values between both regions, we used the Gamma statistic. We also compared pairs of indicator values calculated for each species with Wilcoxon Matched Pairs tests.

Results Results showed that indices developed for Greece and Italy were not similarly correlated to sample scores along DCA axis 1. Species indicator values for Italy and for Greece were highly significantly correlated for light and moisture and significantly correlated for temperature, but the correlations were weak (0.20 <Gamma <0.31) Pairwise testing gave significantly different indicator values for both regions. Discrepancies below or equal to 2 units on the 9-point scales (12-points for moisture) were found for 88, 70 and 54% of the species respectively for light, temperature and moisture indices. A substantial number of species showed higher discrepancies from 3 up to 6 units.

Main conclusions In the light of the present work, it seems clear that the indicator values developed for Italy and for Greece should not be used outside the region for which they were defined. This constitutes additional evidence that the indicator values can be influenced by the identity of potential competitors. It also underlines the need for using standardised methods for calibrating indicator values against measured variables in such a way that indicator systems can serve as general reference systems.
Originele taal-2English
Pagina's (van-tot)62-68
Aantal pagina's7
TijdschriftJournal of Biogeography
Volume34
StatusPublished - 2007

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