With Ellenberg indicator values towards the north: does the indicative power decrease with distance from Central Europe?

Aim: Ellenberg indicator values (EIV) are frequently used in regions outside their Central European origin as proxies for environmental conditions, a practice further boosted by the increasing scientific focus on global change. The performance of EIV outside their geographic origin and over long gradients has, however, rarely been tested. The aim of this study was to evaluate if the indicative power of EIV changes over a large geographic gradient and to analyze the potential causes of such changes. Location: Sweden Taxon: Vascular plants Methods: We used data on forest understory vegetation and soils from >15 000 plots from the Swedish National Forest Inventory to model how the relationship between community mean EIV and measured environmental variables changes along an extensive latitudinal gradient (>15°). We used Generalized Additive Mixed Models to account for the inventory design, and for potential non-linearities in the relationship between the mean EIV and the environmental...