Global Ecology and Conservation (Apr 2022)
A winner or a loser in climate change? Modelling the past, current, and future potential distributions of a rare charophyte species
Abstract
Due to human–caused eutrophication and rapid environmental changes, charophytes have become an increasingly rare component of biosphere. One of the rarest charophyte worldwide is Lychnothamnus barbatus, the only extant representative of the genus Lychnothamnus. The species occurs in Europe, Asia, Australia and North America, but the number of locations is scarce and the geographical distribution is uncertain. In this study, multiple species distribution models (SDMs: Bioclim, MaxEnt, random forest (RF) and support vector machines (SVMs)) were used to reveal the potential undiscovered locations and ranges of L. barbatus. We aimed to (1) indicate the most reliable SDM for L. barbatus; (2) determine the most important bioclimatic factor(s) affecting this species distribution; and (3) estimate the current, past (ca. 130 ka) and future (up to 2100) habitat suitability of L. barbatus in Europe and North America. Future climate scenarios were calculated using four global climate models (GCMs): CanESM5, CNRM–CM6–1, MIROC 6, BCC-CSM2-MR and model ensemble. We documented that a SVM model, which is relatively rarely used in SDMs, performed better than commonly used MaxEnt and RF models. The most important predictors for the SVM (i.e., temperature in wettest, warmest and driest quarters; precipitation in warmest and wettest quarters) were partly different than those for MaxEnt (temperature in wettest quarter and annual temperature range). The SVM used predictors more efficiently than did MaxEnt to achieve good performance. Thus, we recommend further exploring the potential of SVMs in SDMs. Furthermore, we tested different GCMs and demonstrated that the predicted future range of Lychnothamnus is heavily dependent on the model type. Nevertheless, all the models indicated expansion of L. barbatus to other areas in Europe when the pessimistic scenario occurred. It is important for biological conservation of currently rare species—more effort could be put to conserve other, warming–vulnerable species.
