Equações de volume para estimativa de biomassa de castanha-da-amazônia

Abstract

The study was realized in the Cajari River Extractive Reserve, located in the south of Amapá, to develop the specific Amazon nut volume equation. As the Amazon nut slash is prohibited, for the strict cubage were used 24 Amazon nut trees (sample units) have fallen or felled. The cubage was held by Smalian method combined with Hohenald. We adjusted 13 mathematical models (4 single-entry and 9 double-entry), via regression analysis, to estimate the commercial volume with bark of trees. The actual volume obtained from 24 Amazon nut trees was 436.44 m³, with average of 18.19 m³ and a standard error of 2.40 m³. For the simple-entry models, the Koperzky- Gehrhardt equation reported the best fit (R²aj = 0.86; Syx (x) = 23.88%). For the double-entry, Schumacher-Hall model, in his structure no linear, was the best (R²aj = 0.90; Syx (x) = 20.3%). There was no significant difference between the two equations (T = 0.0563; p = 0,955; GL = 46). Single and double input models showed good fits to estimate the Amazon nut timber volume, with data of diameter and height. Therefore, the Koperzky-Gehrhardt may be indicated as more viable procedure for studying Amazon nut volume, because only the diameter variable was used as a predictor. Adding height to the best double-entry model, generates a decrease of 4% in the estimates error, but as the variable height is more susceptible to inventory measurement errors, we recommended the use of single input model