Dinâmica foliar e crescimento de Bertholletia excelsa Bonpl. em resposta a tratamentos silviculturais

Abstract

Bertholletia excelsa Bonpl. is a partially shade tolerant forest species of great socioeconomic and ecological interest. The species has been used in different planting systems (for example, pure plantations, enrichment plantations and agroforestry systems). The photosynthetic plasticity of the species has been indicated as an important mechanism for the establishment of B. excelsa in different environmental conditions. However, changes in leaf dynamics as a growth strategy have not been evaluated. In this study, the main objective was to investigate the influence of silvicultural treatments on the leaf dynamics and the changes associated with growth rates and photosynthetic performance of B. excelsa seedlings. The seedlings were planted under different levels of canopy refinement (0, 20, 40, 60, 80 and 100% of basal area reduction) together with the removal of understory. The leaf production was six and five times higher in 80 and 100% when compared to control plots. The growth rates (diameter and height) also increased with the intensity of silvicultural treatments. Changes in growth were positively associated to variation in leaf liquid gain. Silvicultural treatments also affected the leaf age composition in the different environments, which not exhibited significant differences in the photochemical performance. Changes in leaf dynamics represent important mechanisms associated with the growth responses of B. excelsa to silvicultural treatments.