Yield and structure of two Brazil nut (Bertholletia excelsa O. Berg) native populations in Roraima.

Abstract

This work was carried out with the objectives of studying the population structure, spatial distribution, height -diameter curve and the fruits and seeds yield of Brazil nut in two native populations in the south of the state of Roraima, Brazil. Two permanent sample plots of 300 x 300 m were located and all the individuals with DBH (diameter at breast height) ≥ 10 cm, were identified, mapped and measured. In each tree were appraised the light climate, crown form and the lianas load. To identify the spatial distribution pattern was used the medium variance/average rate and the Morisita^’s Index. The height – diameter relationship was obtained by regression analysis, being tested 6 models. The yield data were obtained by the count of the fruits, and weight of seeds of 150 trees during the year of 2006. As results, great predominance of adult individuals was observed (DBH≥ 50 cm), representing 69% of the total tree number. Young individuals (DBH <50 cm) corresponded to 31%. The space distribution analysis showed that adult individuals presented random distribution and the youngs tendency of grouping. The model presented the best fit to describe the height – diameter relationship should be fitted separately by place. The medium number of produced fruits was of 23 with a medium of 4,07 kg of seeds by tree.