AJUSTE E SELEÇÃO DE MODELOS VOLUMÉTRICOS DE ESPÉCIES COMERCIAIS NO MUNICÍPIO DE IPIXUNA (PA).

Determining equations to estimate with precision the volume of commercial trees is relevant for decision taking on the use of the forest and on the establishment of public policies for the monitoring and control of natural resources, their valorization and investments. Current paper develops volume equations for the Dense Ombrophilous Forest in Ipixuna, northeastern region of the state of Pará, Brazil. The real volume of 296 sample trees was determined according to the Smalian method. Forty-six trees were selected for a database for the validation of the equations. Twelve mathematic models were tested, of which six had simple entrance and six had a double entrance. Simple entrance models proved to have the best adjustment quality for the Hohenald & Krenn model, with equation v = 5.29918-0.1374d+0.00010d² (R²aj. = 0.84, Sy.x% = 19.81; DMP% = -3.63). In the case of double entrance, the best was Schumacher & Hall model, with equation Logv = -3.7657+1.9242.logd+0.7540.logh, (R²aj. = 0.96, Sy.xr% = 10.46, DMP% = -0.34). After validation of selected equations, the Schumacher & Hall was recommended to estimate the volume of commercial trees in the municipality of Ipixuna due to high precision adjustment. [ABSTRACT FROM AUTHOR]