A deciduidade foliar indica a vulnerabilidade de espécies lenhosas ao fogo

Abstract

Studies demonstrated that the occurrence of fires may cause phenological behaviours that diverge from commonly described patterns. The aim of this study was to evaluate whether the vulnerability of woody species to fire can be indicated by leaf deciduousness. The activity index and the intensity index of different phenophases were compared between burned and unburned individuals of woody species with different levels of leaf deciduousness (deciduous, semideciduous and evergreen). For the deciduous species, the vegetative phenophases were similar between burned and unburned individuals. For the semideciduous species, burned individuals showed higher intensity and activity of the vegetative phenophases. For the evergreen species, the stimulus for production of new leaves and retardation of expanded and senescent leaves was recorded in burned individuals. In terms of reproductive phenology, in burned individuals, lower intensity and activity of unripe and ripe fruits were recorded for deciduous and semideciduous species, whereas the stimulus for flowering and fruiting was recorded for evergreen species. The periodicity of the phenophases can be modulated by the occurrence of fire even after an interval of two years. The effect of the fire was gradually more pronounced from deciduous to evergreen species, indicating the higher vulnerability of evergreen woody species to this type of disturbance.