Resumo. ABSTRACTThe study aimed to calibrate the model 3-PG forEucalyptus salignafor the following the diameter variablesat breast height (DBH), total height, wood volume and branch, bark and wood biomass. The study tookplace in the region of Guaíba, Rio Grande do Sul state, Brazil. Clonal plantations ofEucalyptus salignainvarious spacings were used. Six different ages were selected along the crop cycle (2nd to 7th year). Afterthe forest inventory was carried out, the biomass of three trees fractionated into wood, bark, branches andleaves was collected. The biomass of roots on the average tree of each plot was measured to a depth of 1m. Physical and chemical analyses were performed in soil samples from the layers: 0 to 20 cm, 20 to 40 cmand 40 to 100 cm. Litter deposition was estimated by allocating 4 square collectors of 0.5 m². The leaf areawas obtained through digital photographs and thus the specific leaf area was estimated. The physiologicalparameters were measured in six plots, one at each age. Climatic parameters were provided by EEA ofUFRGS University, located in Eldorado do Sul, RS state. The model validation was not statistically accepted, but their estimated data can be used to estimate the studied variables, demonstrating the potential ofits use although additional studies for the application of the model to this species are still needed.