Eucalypt modeling as a function of spatial arrangement in agrosilvopastoral systems

The objective of this study was to evaluate height-diameter, volumetric, and taper models to estimate tree height and volume to describe the bole profiles of a eucalypts clone established in three agrosilvopastoral spatial arrangements (18 × 2.5; 5 × 2 + 40; 3 (3 × 2) + 30) in Coronel Xavier Chaves, Minas Gerais state, Brazil. The diameter at breast height, total height, and diameter outside bark along the stems of the sample trees were collected. Height-diameter, volume, and taper models were fit to the observed data for each spatial arrangement and were compared to select the best alternative. The mean annual increment for single, double, and triple lines at 48, 60, and 72 months of age, respectively, ranged from 26.0 to 34.6 m 3 ha −1 year −1 , as well as individual volume ranged from 0.41 to 0.53 m 3 tree −1 . The height-diameter curves showed a distinct tendency for each spatial arrangement and can be represented by different equations. The equations to estimate volume and taper fit well to the data, and the Spurr and Garay models were selected as the best fitting, respectively. In addition, Graybill's F-test (Theory and application of the linear model. Duxbury Press, Massachussetts, 1976) showed that a single equation could fit the Spurr and Garay models for all spatial arrangements.