Main Article Content
The objective of this study was the evaluation of the heartwood diameter (dcerne) at breast height on stand trees, for Eucalyptus globulus Labill and the hybrid Populus x euramericana. The data used was collected in eucalyptus and popular pure plantations in Central and North Portugal. The non destructive methods tested in the evaluation of heartwood diameter at breast height were  visual identification of the heartwood on core samples and  indirect estimation using mathematic models. The results allow to consider that visual determination of dcerne is appropriate for Populus, and development of prediction models based diameter at breast height (d), total height (h) and age (t), give better results for eucalyptus.