Variation of heartwood and sapwood in 18-year-old Eucalyptus globulus trees grown with different spacings

Abstract

Heartwood and sapwood development was studied in 18-year-old Eucalyptus globulus trees from pulpwood plantations with different spacings (3 9 2, 3 9 3, 4 9 3, 4 9 4 and 4 9 5 m), on cross-sectional discs taken at breast height. The trees possessed a large proportion of heartwood, on average 60% of the wood cross-sectional surface. Spacing was a statistically significant source of variation of heartwood area, which ranged between 99 and 206 cm 2 for the closer (3 9 2) and wider (4 9 5) spacings, respectively. There was a positive and high statistical significant correlation between heartwood diameter and tree diameter (heartwood diameter = -0.272 ? 0.616 dbh; r 2 = 0.77; P \ 0.001), and larger trees contained more heartwood regardless of spacing. Heartwood proportion in cross-section remained practically constant between spacings but increased with tree diameter class: 55.1, 62.2, 65.0 and 69.5% for diameter at breast height classes \15, 15-20, 20-25 and [25 cm, respec-tively. The sapwood width did not depend on tree diameter growth and remained practically constant at an average of 18 mm (range 15-21 mm), but sapwood area showed a good linear regression with tree diameter. Therefore, tree growth enhancement factors, such as wide spacings, will induce formation of larger heartwoods that can negatively impact raw-material quality for pulping. The increase in heartwood in relation with tree dimensions should therefore be taken into account when designing forest management guidelines.

Acacia melanoxylon in Argentina: heartwood content and its relationship with site, growth and age of the trees

“…In A. melanoxylon plantations in New Zealand, Haslett (1986) pointed as usual a thickness of 2-5 cm, whereas in 18-year-old trees (DBH= 15.3 cm) in Tasmania, Bradbury et al (2011) reported a thickness of 2.7 cm, values that are in agreement with that observed in this study. On the other hand, a constant thickness of sapwood along the stem has also been observed in other commercial genera such as Eucalyptus (Hillis, 1987;Taylor et al, 2002;Miranda et al, 2009). The amount of sapwood in a tree is related to its conductive needs that are in relation with its crown development and therefore, the formation and development of heartwood progresses within the tree to regulate the amount of sapwood (Bamber, 1976;Berthier et al, 2001).…”

“…The amount of sapwood in a tree is related to its conductive needs that are in relation with its crown development and therefore, the formation and development of heartwood progresses within the tree to regulate the amount of sapwood (Bamber, 1976;Berthier et al, 2001). This explains the different distribution pattern of heartwood and sapwood within the stem and the positive relation of tree growth with heartwood content (Climent et al, 2002(Climent et al, , 2003Bradbury, 2005;Searle & Owen, 2005;Knapic et al, 2006;Gominho & Pereira, 2000, 2005Miranda et al, 2009).…”

“…Several authors consider the age of the trees as the main factor that control the contents of heartwood and sapwood (Harrison, 1974;Stokes & Berthier, 2000;Taylor et al, 2002;Climent et al, 2002Climent et al, , 2003Bradbury, 2005;Searle & Owen, 2005). It has also been found that the content of heartwood is related to the growth rate, the site, the silvicultural practices, and a moderate genetic control (Hillis, 1987;Zobel & Jett, 1995;Taylor et al, 2002;Knapic et al, 2006;Gominho & Pereira, 2000, 2005Miranda et al, 2009;Bradbury et al, 2011). However, in the present study, we found no significant linear relationship between the heartwood content (both in relative and absolute terms) and the age, at least at the age ranges that characterized this material (9-32 years).…”

“…Besides this, the economic interest in heartwood/sapwood ratio for a number of forest species has directed numerous research efforts to the study of the relations between heartwood and other traits of the tree, eg. the relevance of tree age or radial growth on heartwood width (Bamber, 1976;Taylor et al, 2002;Climent et al, 2002Climent et al, , 2003Bradbury, 2005;Searle & Owen, 2005;Knapic et al, 2006;Gominho & Pereira, 2000, 2005Miranda et al, 2009).…”

Variation of wood and bark density and production in coppiced Eucalyptus globulus trees in a second rotation

“…It is also an objective to compare data on wood density, tree volume and stand productivity of the coppice with the first single stem previous rotation, since this data is available from previous studies (Miranda et al 2003(Miranda et al , 2009). This will allow for estimating changes between the two cutting cycles and therefore better adapt the silvicultural management.…”