Dinâmica de crescimento de Centrolobium robustum (Vell.) Mart. ex Benth. (Leguminosae-Papilionoideae) na Floresta Atlântica, Rio de Janeiro, Brasil

Abstract

Radial growth rhythm and tree longevity are essencial to understand forest dynamics, as well as species development and survival. However these studies are still scarce in the tropics, despite the urgent need for preservation and management of its forests. The objectives of this study are: i) to describe cambial activity and phenology of Centrolobium robustum (Vell.) Mart. ex Benth., correlating these parameters to each other; ii) To evaluate the influence of climate seasonality and photoperiod on cambial activity and phenology and iii) To characterize the structural pattern of growth rings and to determine, from them, the age and radial growth rates of C. robustum in Tinguá Biological Reserve, RJ. For the analysis of cambial activity, samples were collected quarterly and processed according to usual techniques of plant anatomy. The material was observed under light, fluorescence, polarization and transmission electron microscopy. Phenological monitoring was conducted monthly and activity and intensity indexes were used to analyze the vegetative and reproductive phenophases, respectively. For dendrochronological investigations, samples collected with an increment borer were polished and observed in stereoscopic microscope. The results showed an annual cycle of the activity and dormancy, characterized respectively by the presence of cells undergoing division and differentiation next to the cambium and by fully differentiated cells and callose deposition in sieve tube elements adjacent to the cambial zone. Cambial dormancy coincided with leave senescence and fall, while activity was more evident while adult leaves were present in the canopy. Seasonality of cambial activity showed significant correlation with temperature, precipitation and photoperiod in the sampling month. Seasonal cambial activity in association with climate and phenology of the species was determined, allowing characterization of the growth rings as annual. Results allowed the establishment of the dendroecological pattern of C. robustum and the ages and growth rates of the studied trees.