Drought-induced effects in coexisting Mediterranean shrubs in relation to species' bioclimatic niche

Climate-induced drought is one of the principal factors altering plant community dynamics and composition as well as species' geographic distributions in the Mediterranean basin. The use of bioclimatic models that consider both bioclimatic conditions and species' geographic distributions to predict potential scenarios under these climatic conditions have recently become extensively developed. However, studies relating the effects of drought over community dynamics with regional-scale patterns are very scarce. Here I relate field observations made in a Mediterranean community (NE Iberian Peninsula) on the effects of a climatic drought anomaly over local-population traits driving community dynamics (abundance and resistance to drought estimated from defoliation) with the species bioclimatic niche assessed at regional scale from Species Distribution Models. Results highlight that species' abundance increases when the average bioclimatic conditions are more suitable. Resistance to drought is not related with species' bioclimatic suitability at such locality, estimated from average climatic conditions, but it diminishes when the displacement induced by the climatic anomaly over the species' bioclimatic suitability is higher. Less frequent species appears more resistant than more common ones, suggesting the relevance of acclimation or natural selection over populations, and thus determining community dynamics under climate change scenarios. These results suggest that a drought climate scenario could lead to shifts in community dynamics and species' distributions and the emergence of new communities better adapted to the new conditions. I conclude that bioclimatic models can reflect both regional and local scale patterns and can be useful to predict community shifts in front of bioclimatic anomalies and I provide a procedure to link patterns at such distant scales. Further investigation is needed to assess and improve the prediction ability of this procedure as well as the importance of these climatic anomalies