Functional characterizations of Ellenberg indicator values - a review on ecophysiological determinants

Ellenberg indicator values (EIVs) can be used as a numerical system to classify species' habitat niches and their peak occurrence along gradients. By finding correlations of EIVs with morphological or ecophysiological properties, it is possible to identify determinants of species distributions with respect to environmental factors. We surveyed existing literature containing species comparisons from controlled experiments and combined them with EIVs. The picture emerging is that multiple determinants can be identified for nutrient numbers (N), soil reaction numbers (R) and also soil moisture numbers (M), while only few can be found for light numbers (L) and especially for continentality (C) and temperature numbers (T). Functional characterizations of the different EIV can thus be deduced which help to understand the mechanisms and processes driving the ecological niche of a plant. The described approach is a powerful tool to analyse the ecological significance of different plant properties. Species screenings specifically designed to allow for correlations with EIV have large potential for high explanatory power.