Probability of germination after heat treatment of native Spanish pines

Spanish pine forests exhibit a high degree of resilience to frequent wildfi res. For this reason, they have been considered as active pyrophytes. Howev er, the primary evidence of the fire response of some of the seven Spanish pines suggests that they are not real pyrophytes because germination enhanc ement has not been detected. In order to investigate the germination respon se of the Spanish pine seeds after heating, seeds were submitted to differe nt treatments at varying temperatures (50-130 degrees C) and exposure times (1-15 min) to simulate responses to different fire regimes and situations. The probability of germination after heating was modelled by means of mult iple logistic regressions using temperature, time and their interaction as predictors. Very predictive models were found for all the pines, except for Pinus pinea. Seeds germinate readily without treatment, losing their viabi lity within a short time and showing a slight protection from fire. The res ults suggest that, despite the fact that these pines all occur in fire-pron e environments, their germination behaviour has clearly not evolved in rela tion to fire alone. Furthermore, seed behaviour is not related to the gener al syndromes described as typical of fire-evolved plants. Whereas most of t he Mediterranean seeders base their efficient recruitment after wildfires o n the presence of hard-coated seeds, most of the Mediterranean pines have a ttempted other strategies with some variants related to prolific seed produ ction. Only P. pinea regeneration after wildfires depends on the existence of fire-resistant and hard-coated seeds. ((C) Inra/Elsevier, Paris.).