Phenology and wood density of plants growing in the semi-arid region of northeastern Brazil

摘要

Nineteen woody species growing in the semi-arid region of northeastern Brazil were examined to evaluate the relationship between wood density and their vegetative and reproductive phenophases. Wood density varied between 0.29 g/cm3 and 0.83 g/cm3, and these values were inversely related to the quantity of water stored at saturation. The six species that initiated vegetative and/or reproductive phenophases during the dry season had low wood densities (<0.55 g/cm3) and were able to store large quantities of water (110-271% of the dry weight of the wood). Leaf fall in these species occurred during the transition period between the rainy and the dry season, and it occurred earlier than in species with denser wood. Leaf flush among low wood density species was positively related to the photoperiod. Species with high wood densities, on the other hand, were strongly dependent on rainfall for leaf flush, flowering, and fruiting, as they are able to store only limited quantities of water in their trunks; leaf fall in these species occurred during the dry season. These results point to a strong correlation between wood density and phenology among the species studied.