Well-known bioindicators of forest health, air and soil quality, lichens are also considered potential indicators of climate change. Drivers of changes to lichen proliferation and distribution, however, may be linked, and disentangling effects is necessary to understand the true impact.
To explore the validity of lichens as indicators of climate change, this study used GBIF-mediated occurrences coupled with Worldclim bioclimatic data to model habitat suitability of 45 designated indicator species in Central Europe. Only 17 species, however, had sufficient historic data for modelling.
The resulting models revealed that half the investigated species had substantial fractions of their modern occurrences in areas previously considered unsuitable, while the majority of records for just under half of the species were found in suitable climates.
While data was lacking for many proposed indicator species, the results of modelling for half the species with sufficient data showed that distributional shifts occurred within areas historically considered suitable, indicating that taxa may be responding to other, more local drivers such as shifting pollution.
These results question whether the remaining taxa are indeed strong positive indicators of climate change, and the authors call for more quantitative, evidence-based derivations of indicators.