D³ database

Ranking Indices

RANKING INDICES are indices that allow an assessment how well a species is adapted to a certain dispersal mode in comparison to other species and dispersal modes. They are derived from indicators, i.e. dispersal traits or experimental assessments.

RANKING INDICES are here calculated as the percentile rank of this indicator in relation to all species for which data are available in D³. They range from 0 to 1 with 0 addressing species with the lowest and 1 addressing species with the highest dispersal potential (details see in the respective section). Please note that we used the lowest rank in case of identical values.


For example, Fraxinus excelsior (anemochory ranking = 0.70, epizoochory ranking = 0.01, hydrochory ranking = 0.17) is well adapted to anemochory (wind dispersal). 30 % of the species for which data are available in D³ show a lower (or identical) terminal velocity and are better (or equal) adapted to wind dispersal. In contrast, F. excelsior shows nearly no adaptation to epizoo- or hydrochory in comparison to the other species in the database.