Modeling of Brazil nut tree fruit production in the Eastern Amazon

Abstract

The objective of this work was to evaluate the variation in the fruit production of Brazil nut (Bertholletia excelsa) trees in the Eastern Amazon through geostatistical techniques and generalized linear models (GLMs). A nine-hectare permanent plot in the Cajari River extractive reserve was analyzed. All trees (61) with diameter at breast height (DBH) ≥10 cm were evaluated. Within each plot, 43 subplots of 250 m² were established for sampling vegetation and soil at a depth of 0–20 cm. The data were processed using geostatistical techniques and the Poisson and negative binomial GLMs. The 20 evaluated variables showed spatial dependence. Although both models were fit to estimate fruit production, the negative binomial model better accommodated data variability. Tree diameter and soil physical attributes (density, clay, and water content) better explain the variation in fruit production, together with magnesium and carbon content that are the main chemical soil properties associated with higher yields.