Different approaches on seed germination to look into global warming effects on Araucaria angustifolia

Abstract

Araucaria angustifolia is a key species in the South America. Trustworthiness of the forecast reduction of Araucaria forests due to the global warming requires germination studies. We simulated daily temperature oscillations based on soil temperatures observed in the summer and obtained greater germination performance as compared to when germination was studied under constant temperatures. However, A. angustifolia seeds are dispersed in the winter, and germination performances obtained either under daily temperature oscillations or constant conditions suggest that these seeds require temperatures that are higher than those we observed in its natural habitat during seed dispersal. Therefore, these seeds may not germinate immediately after dispersal in the field. Based on scientific projections, only unlikely temperature raises will lower germination performances of A. angustifolia seeds, eventually affecting its success. We propose that germination performance measured under constant temperatures must be carefully interpreted and that laboratory data intended for extrapolation to field conditions needs a more complex model, still not available.