The development of heartwood and sapwood in blackwood (Acacia melanoxylon R. Br.) was studied in a total of 20 trees with a 40-cm-diameter class sampled over four stands in northern Portugal at harvest for timber production. Stem discs with 5-cm thickness were taken at different height levels (stem base and 5, 15, 35, 50, 65, 75, 85 and 90 per cent of total height). Crosssectional area and heartwood area were measured by image analysis. Heartwood represented a substantial part of the trees and within the tree it attained on average 81 per cent of total height, and represented 69, 62, 58 and 44 per cent of the stem cross-sectional area, respectively, at 5, 35, 50 and 65 per cent of total tree height. The heartwood followed closely the stem wood profi le both axially and radially. Estimation of heartwood dimensions from external wood diameters (either over or under bark) was possible using a linear model, which had a very high correlation coeffi cient (R 2 = 0.97). The sapwood radial width showed a very small variation within and between trees and maintained a constant value of 31 mm up to ∼ 65 per cent of tree height. No site infl uence was found for the heartwood development and the between-tree variation was small. The species and the sampled individuals in Portugal showed potential for the diversifi cation of forest production and increasing the industrial supply of a valuable timber hardwood.

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Eucalypt wood is known worldwide as a raw-material for pulping but only a few species are used by the industry. One of the important features for pulping is the wood structure and anatomy, including cell biometry and cell type proportion. This work makes a prospective study of nine eucalypt species aiming at a pulping use by an early assessment of wood anatomical features. Young 50-month-old trees grown in the same environment of Eucalyptus camaldulensis, Eucalyptus globulus, Eucalyptus maculata, Eucalyptus melliodora, Eucalyptus ovata, Eucalyptus propinqua, Eucalyptus sideroxylon, Eucalyptus tereticornis and Eucalyptus viminalis were studied in relation to wood anatomy, cell biometry and proportion, and morphological fibre ratios. The nine species are structurally similar with typical eucalypt wood features, e.g. diffuse porosity with predominantly solitary vessels and simple perforations plates, and most anatomical differences between species related to rays and axial parenchyma. The wood is in general uniform and the radial variation of cellular dimensions is of small magnitude. The species showed a higher diversity regarding proportion of fibres (15-50%) and morphological characteristics e.g. slenderness ratio (39-48) and flexibility coefficient (0.37-0.65). The eucalypt species position themselves differently as regards the combination of morphological parameters, therefore allowing species targeting for specific paper properties. By considering these indicators, and the relative species growth, it seems promising to further study E. maculata, E. ovata and E. sideroxylon as potential new paper making eucalypt species, in parallel to the prized E. globulus and the already used E. camaldulensis.

-The radial variation of ring width and wood density was studied in cork oaks (Quercus suber) using microdensitometry. The observations were made in young never debarked cork oaks (30-40 years of age) and in mature trees under cork production (37-60 years of age). The cork oak wood is very dense (mean ring density 0.86 g.cm −3 , between 0.79 g.cm −3 and 0.97 g.cm −3 ) with a small intra-ring variability (mean earlywood density 0.80 g.cm −3 and latewood density 0.90 g.cm −3 ). The density components decreased from pith to bark more rapidly until the 15th ring, and then only slightly. There were no significant differences in the mean density components between never debarked trees and trees under cork production but their outwards decrease was accentuated in the never debarked trees. The annual growth was high, with a ring width mean of 3.9 mm (4.2 mm in the first 30 years) and the latewood represented 57% of the annual growth.Quercus suber / cork oak / density / ring width / latewood Résumé -Variation radiale des composantes de la microdensité du bois et de la largeur de cerne dans le chêne-liège. La variation radiale de la largeur des cernes et de la densité du bois a été étudiée dans le chêne-liège (Quercus suber) par microdensitométrie. Les observations ont été réalisées dans des arbres jeunes jamais écorcés (âge 30-40 ans) et des arbres en phase de production de liège (37-60 ans). Le bois de chêne-liège est très dense (densité moyenne 0,86 g.cm −3 , variant entre 0,79 g.cm −3 et 0,97 g.cm −3 ) avec une variabilité dans le cerne faible (densité moyenne du bois initial 0,80 g.cm −3 et du bois final 0,97 g.cm −3 ). Les composantes de la densité diminuent du coeur à la périphérie rapidement jusqu'au 15 e cerne, puis plus lentement. Les différences entre valeurs moyennes des composantes de la densité du bois des arbres non écorcés et écorcés ne sont pas statistiquement significatives, quoique la diminution radiale soit plus accentuée dans les arbres non écorcés. La croissance annuelle était élevée avec une largeur moyenne de cerne de 3,9 mm (4,2 mm dans les premiers 30 ans) avec le bois final correspondant à 57 % de la croissance annuelle.Quercus suber / chêne-liège / densité / largeur de cerne / bois final

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