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

Abstract

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 analyse the potential causes of such changes. Location Sweden. Taxon Vascular plants. Methods We used data on forest understorey 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 nonlinearities in the relationship between the mean EIV and the environmental variables. Additionally, Huisman–Olff–Fresco (HOF) models were developed for the relationship between the incidence probability and the environmental variables to analyse if the widths of species niches change along the geographic gradient. Results Our study shows that EIV for N (nutrients), R (pH) and T (temperature) are useful as far north as the Arctic Circle, while those for K (continentality) showed a much weaker relationship with measured continentality. However, the indicative power of the EIV for N and R gradually became weaker towards the north along with shifts towards larger environmental niche widths of the indicator species. Main conclusions EIV are useful indicators of soil conditions in boreal forests located far north of Central Europe. However, the drop in indicative power in the northernmost regions due to increasing environmental niche widths needs to be taken into account when applying EIV along long geographic gradients to avoid spatial bias.

Grasslands ancient and modern: Soil nutrients, habitat age and their relation to Ellenberg N

“…Although the occurrences of individual species could not simply be explained by particular soil nutrients, most species nevertheless showed preferences for nutrient concentrations that, in general, corresponded to their Ellenberg rankings (N1–N8; Figure , Appendix ) — confirming that the Ellenberg N‐values represent indicators that can be used to characterize the overall nutrient preferences of individual species. Our local study in Sweden supports other studies (Hedwall, Brunet, & Diekmann, ; Hill et al, ) that also confirm that Ellenberg N‐values are applicable outside Central Europe.…”

Ellenberg N values of bryophytes in Central Europe*

“…Hill et al (2007) provide Ellenberg-style scores for the UK and Ireland;however, Hill et al (2005) make clear that a comparison of their values for British and Irish bryophytes with corresponding values for, e.g., Central Europe, will not be meaningful due to considerable differences in climate and ecology. This accords with Hedwall et al (2019), who have shown decreasing reliability of EIVs outside of Central Europe.…”

“…This is why EIV values are regarded as a valuable tool and widely used in applied ecology (e.g. Bratli et al, 2006;Chytrý et al, 2009;Bartelheimer and Poschlod, 2016), also outside of Central Europe (Shipley et al, 2017;Hedwall et al, 2019).…”

Rapid plant colonization of the forelands of a vanishing glacier is strongly associated with species traits

“…The Faroe Islands are environmentally similar to the study area and represent the only colder region for which Ellenberg values have been calibrated (cf. Hedwall, Brunet, and Diekmann 2019). When information was missing for some species in Lawesson, Fosaa, and Olsen (2003), original Ellenberg values were used as described in Ellenberg et al (1992), and when still missing, values from Hill (1999) were used.…”